At Maidenhead Aquatics we pride ourselves in the fact that all our staff have a keen interest and experience in keeping fish. For this reason we have many years of fishkeeping expertise and are more than likely to be able to answer any questions that you may have. In fact lots of our stores have won awards due to the dedication of our staff and their ability to know how to keep our fish correctly.

Take a look at our growing list of questions and if you cannot find the answer you require here, then please feel free to contact your local Maidenhead Aquatics store where our knowledgeable staff will be more than happy to advise you.

How many of each fish should I keep?

Very few species of tropical fish are naturally solitary or pair forming and so most need to be kept as shoals or groups for best results. Tetras, barbs, rainbowfishes and catfishes such as Corydoras are found in vast numbers in the wild and will only exhibit natural behaviour when able to interact with a number of their own kind. Signs of unusual behaviour may include aggression towards other tankmates and an otherwise peaceful community species can exhibit unusual behaviour such as fin-nipping. 

Many fish that exhibit marked differences in colouration are sold as pairs to ensure the sale of the somewhat more plain females but without females to impress, males often fail to display their bright colours. Species such as gouramies fall into this category and are best kept as multiple pairs in large well-planted aquaria. Amongst the few species that do need to be kept as pairs are some of the monogamous cichlids but even these prefer to select their own mates and are best kept initially in groups when young. 

By contrast, most marine fishes are territorial and aggressive and should be kept singly in the case of average-sized aquaria. Some species can be kept in pairs or small groups but these are the exception and should ideally be seen together before purchase and introduced simultaneously for best results.

Is it ethical to buy wild-caught fish?

The overwhelming majority of tropical fishes seen in shops are bred in tanks or ponds and may represent forms that are unknown in the wild. Free from the pressures of predation and competition, albino and long-finned forms of many species have been bred and would not survive in a wild situation. Due to environmental damage, a number of species familiar to aquarium keepers are threatened or even extinct in the wild such as the Redtailed Black Shark (Epalzeorhynchus bicolor) or the Cherry Barb (Puntius titteya) and for these, popularity as aquarium fish ensures their survival.
A much smaller proportion of fishes in the trade consist of those that are collected from the wild. In the case of freshwater species, many of these are harvested from areas where massive seasonal fluctuations in water levels mean that a surplus of individuals are destined to die in the dry season and represent a very sustainable means of income for local people. As such, these small fishes remain a valuable commodity to be protected and with them their habitat - ensuring the preservation of biodiversity and discouraging destructive land use. As long as the species are those that will thrive under captive conditions, such sustainable use of a renewable resource is to be encouraged and in these enlightened times valuable work in nature reserves can be financed by the judicious collection of wild-caught fish.
Unlike their captive-bred counterparts, wild fish are used to optimal water conditions and will often prove problematic if your aquarium water is high in pollutants such as nitrate or phosphate. Make sure that these levels are acceptably low before introducing any new fishes to your aquarium.

Is there a dominance hierarchy amongst corals?

Like trees in a forest, corals are in competition for space and light in a reef environment. Because of this, they have evolved ways to defend themselves against their neighbours and these involve stinging with so called 'sweeper tentacles' or indulging in chemical warfare.

Many species that find themselves thrown together in captivity do not occur together in the wild and it is often observed that some corals are prone to damage from neighbouring animals. Soft corals tend to use toxins to fight for space and it is often wise not to mix them with more demanding SPS (small polyped scleractinian) hard corals such as Acropora, a situation that is easily avoided by noting the differences in light levels and current that these animals prefer. LPS (large polped scleractinians) hard corals such as Galaxea are more likely to nettle their neighbours using long tentacles and need to be widely spaced to avoid injury.

Why are most Marine fish so territorial?

Coral reefs are an island of life in otherwise low nutrient seas. Most of the resources are tied up in the tissues of plants and animals and oportunities are limited. Predators are all too eager to consume any animals that lack shelter and any fishes sleeping in the open at night will not often live to see the next morning. If you possess a good hiding place and a food source, there is always someone wanting to take it from you!

Typically, less territorial species feed on abundant food sources such as plankton or open water shoaling fishes. They may be shoaling so they can overwhelm individuals that would successfully guard their food source from smaller numbers of fishes and the large shoals of Tangs such as Convict Surgeons (Acanthurus triostegus) are an effective way of feeding on the algal gardens of other species.

Sex is also an issue close to the hearts of most marine fish and the fact that many species compete for the role of dominant male or female serves to make them even more aggressive.

Apart from the zooxanthellae, how else do corals feed?

Not all corals live in sun-drenched shallows, or grow slowly enough to gain all their nutrient needs from their symbiotic algae.

Depending on polyp size, corals catch various planktonic organisms from the surrounding water and will often display a distinctly different appearance at night or when tides and currents bring feeding opportunities. Feeding tentacles equipped with stinging cells enable them to overpower small animals and some of the most remarkable behaviours are displayed by soft corals such as the Elephant Ear Mushroom (Amplexidiscus fenestrafer) which mimics anemones and devours small fish such as clowns which shelter in them.

How does the partnership between algae and coral work?

If you live permanently attached to a site under the tropical sun, it makes sense to be solar powered. Although this is common in plants, animals don't possess the adaptations to photosynthesize and this is where the symbiotic relationship between algae and corals gives both organisms a great advantage.

The algae in question - known as 'zooxanthellae' live within the cells of corals, anemones and giant clams and provide sugars to their host, in exchange for shelter and nutrients in the form of carbon dioxide and nitrogen based waste.

Why are so many Marine fish so specialised in their diet?

In the complex environment of a coral reef, there are huge numbers of species and many of them are in competition. One way to beat the opposition is to specialise in one or two specific food sources or ways to harvest a meal.

An example is the long nose of the Copperband Butterflyfish (Chelmon rostratus) which enables the fish to feed in small crevices inaccessible to shorter nosed species that would otherwise eat the same items. The astonishing feeding technique of the Dragon or Rockmover Wrasse (Novaculichthys taeniourus) is another way of finding food and a pair of adult fishes will alternate between lifting rocks and grabbing small animals sheltering beneath.

A common strategy is to find a food source that other species don't use and avoid competition entirely. Many Butterflyfishes feed on coral polyps of different species, enabling them to live in the same areas without competing with each other. Another strategy is to guard your food source and a number of Tangs, Damselfishes and Blennies are 'Algal Gardeners' and exclude all competitors from their territory where they farm the algae that feeds them - often removing species that they don't eat.

How long do reef fishes live?

Unlike many popular freshwater fishes that naturally live from one wet season to the next, reef fish are built to last. In the wild, the highest mortality rates occur when young fishes settle out of the plankton and have to find a territory of their own - failure results in either predation or starvation. This is why it is always preferable to select small individuals when choosing your marine fish, as this 'post-planktonic recruitment' represents a surplus of youngsters that would naturally fall prey to selection pressures in the wild, rather than removing key breeding adults vital to a healthy population.

Once they have a territory and food source, predation is the greatest issue facing the average reef fish and often the combative nature of fishes such as Damsels means that they can recover from physical traumas that would otherwise prove fatal to less robust freshwater species. There are few marine equivalents of the 'live fast - die young' Livebearers, Tetras and Killifishes seen in home aquaria and so teenage aquarium fish are commonly seen in well maintained reef tanks.

By preventing premature deaths due to water quality, disease or aggression, you can stand a good chance of seeing your reef fish grow to a ripe old age of around ten years for all but the smallest reef fish.

At this point it is timely to add that a number of specialised feeders have no place in the home aquarium and often fail to thrive in aquaria. Species such as Sweetlips, Coral-eating Butterflyfishes and Redfaced Batfish will normally fail to thrive and suffer greatly reduced life expectancies in captivity. This is why we do not agree with their importation and avoid stocking them in our stores.

How do I get rid of black algae in my tank?

Black beard algae is actually a red algae and thrives in high-phosphate environments. What this means is that if you have it in your aquarium, it's either a sign that more waterchanges are needed - perhaps boosted by using a gravel cleaning syphon, or that your tapwater contains high levels of phosphate. As ever, a water test can save a great deal of guesswork and help you tailor a maintenance schedule that suits your aquarium.

Areas where old Victorian plumbing is still in use tend to be the worst for phosphate contamination, as water authorities add this to the water to prevent any corrosion of potentially harmful lead piping. To put this into perspective, black algae may be a nuisance but is preferable to a dose of lead poisoning! If your tapwater tests positive for phosphate, it may be better to switch to RO water to avoid adding more algae-food each time you carry out a waterchange.

With inputs of phosphate minimised and solid waste removed from your aquarium, adding a phosphate removing resin to your filter is a good way to starve out the algae. Old fluorescent tubes can also be a problem and with time, their output can shift to favour the growth of algaes rather than more demanding aquarium plants. Unlike green algaes, few aquatic creatures have evolved to eat black algae but the Siamese Flying Fox Crossocheilus siamensis (also known as the SAE or Siamese Algae Eater) can be used as a means of control. The key to beating this, or any other nuisance algae, is to change the conditions in the aquarium with cause it to thrive.

What is the best way to keep Shrimps in my tropical freshwater tank?

With their bright colours and compact size, freshwater crustaceans have quickly become a popular addition to the aquarium hobby. Many of the varieties appearing in our stores are line-bred forms of less glamorous wild species and as such, will crossbreed and produce less attractive offspring if mixed. As with many fish species, the perfect solution is to pick your favourites and keep a large number! Given their tiny size, a growing number of shrimp-fans are finding it easy to house a number of small aquaria for their expanding collection.

With few exceptions, the popular shrimp species are Asian in origin and a growing number of amazing animals are being found in the Malili lakes of Sulawesi. These species are characterised by a need for alkaline water, which doesn't need to be particularly hard - a small tank of RO water powered by an air operated filter, or small internal power filter with a venturi outlet, will ensure pH and oxygen levels remain high. Stream dwelling species are more tolerant of lower pH systems and are very much at home in planted aquaria using CO2 where their appetite for algae and detritus makes them very useful. Many of these species are happy living at room temperature and will often fail to thrive in systems kept at high temperatures.

As invertebrates, many commonly used aquarium medications are toxic to shrimps (particularly those containing copper) and like their marine relatives, high levels of phosphate and nitrate can prove damaging and especially problematic when animals are moulting. A need for calcium can be met by providing your pets with foods made specifically for them, although they will happily eat most fish foods.

Never forget that your shrimps may be a welcome treat for a number of community fishes such as loaches and dwarf cichlids and make sure that they remain unmolested. For best results, tailor your fish selection to the needs of your shrimps, or enjoy them in a 'desk-top' style nano tank where they can tank centre stage.

Can I keep Goldfish with Tropical fish?

When temperatures are high, nobody keeps coldwater fish. Likewise, in areas of the world where the climate means that even an unheated aquarium runs at tropical temperatures, it is often common practice to keep Fancy Goldfish in with surprisingly different tank mates such as Discus.

Given the delicate nature of some of the highly bred forms of Goldfish, we can see that a nice warm tank is a great environment for them and they will often thrive.
The big problem here is that as a fish with a metabolic rate designed to function at a much lower temperature, Goldfish are simply too messy and demanding to live with tropical species at their preferred temperature. To use an analogy, it would be like attempting to keep rabbits in a stable with a horse! A single goldfish can create a waste load that can lead to levels of pollution that tropical fish cannot tolerate and even if the water remains clear, organic waste levels can lead to fatally high nitrate levels or at the extreme, a filter clogged with solid waste. 

Another side effect of keeping coldwater fishes at tropical temperatures is the much shorter lifespan that will arise due to the fish always being kept at unnaturally high metabolic rates. By keeping your coldwater fishes cool, they will enjoy a much longer, healthier life.

Why are my fish gasping at the water’s surface?

When fish gasp at the surface, it generally follows that they are short of oxygen. Often this is due to other pollutants such as ammonia or nitrite interfering with healthy gill function in the same way that we might fight for breath in a smoky atmosphere or in the presence of noxious fumes. Another problem that can cause the same symptoms is a pH crash and the signs of Acidosis are very similar. So, as we can see, checking water quality parameters should be the first course of action. High temperatures affect the amount of oxygen available and so heating equipment and aquarium temperature should also be scrutinised.
If all water parameters fall within healthy levels, other factors can be reviewed. The presence of large amounts of plants or algae in a system can drop the oxygen levels to a critical point in summer and in heavily planted ponds or aquaria some overnight aeration or extra water movement may be necessary to drive off carbon dioxide and increase dissolved oxygen content.
An over-stocked aquarium or pond can suffer low levels of oxygen due to the metabolic requirements of both fishes and filter bacteria. If your system needs extra aeration to get by, it may be time to review your stocking levels and treat yourself to the larger aquarium or pond you’ve been considering!
There are a few species of fish that will naturally feed by skimming the surface film, such as some livebearers. By observing your fish for signs of distress, you can see what constitutes normal behaviour for your pets.

What puffer fish are suitable for a tropical freshwater community tank?

At first sight this question has a very short answer - none!

Puffers are equipped with powerful bites and short tempers and this combination can spell disaster for delicate community fish that find themselves in close proximity. Puffers are always more peaceful on a full stomach and often vary in character from one individual to the next. If a community of fishes are selected with the pufferfish in mind, compatible species can often be found for a few of the more peaceable types such as the South American Puffer Colomesus asellus.
Fish eating species such as the Congo puffer Tetraodon miurus will always regard tank mates as a menu option and must be kept in a species aquarium. In order not to see your pet’s dark side it is always best to keep puffers in a dedicated set up where you can enjoy their many good points without witnessing the more negative aspects of their character.

How many fish can I keep in my 60 litre tank?

With modern filtration and regular water testing, the old stocking levels quoted by many sources are now a little obsolete. Variables such as size and temperament of fish are factors to be born in mind and all systems will benefit from slow and cautious stocking. Remember that most aquarium fishes are highly social and need to be kept in shoals in order to thrive. Rather than create a ‘Noah’s Ark’ aquarium where fish are stocked two by two, choose your favourites and enjoy the sight of them as a shoal.

Due to the large size and messy nature of goldfish, I would limit stocking to just two fishes that would quickly grow to a size that might make a 60cm aquarium look small. Bear in mind that although the fishes will grow, the tank cannot, so always calculate stocking levels based on adult sizes of the fishes you choose. As the waste levels in an aquarium are linked to stocking densities, a heavily stocked aquarium will require more maintenance than an uncrowded set up. Tropical and subtropical fish communities normally feature small fishes often averaging a little over an inch in length and these are the species of fish most suitable for the smaller aquarium.
Using an old formula of 12” of fish for every square foot of surface area, an Aqua Tropic 60 comes out with a carrying capacity of approximately 24” or 60cm of fish length. Obviously two 30 cm fish would produce a massive amount of waste in comparison to twenty fish 3cm long, so here we see the limitations of this method. A more modern stocking level of 1 cm per litre gives a not dissimilar figure of 65 cm of fish and this can be slightly exceeded with efficient filtration and regular waterchanges. As a guide, twenty small shoaling fishes such as tetras or white cloud mountain minnows will leave scope for a few catfish, shrimps or one or two slightly larger ‘feature fish’.

How do I get rid of the nuisance snails in my aquarium?

Nuisance snails are often a sign of excessive organic matter in the aquarium such as uneaten food, plant remains or detritus. Reviewing feeding regimes and hoovering out debris with a gravel cleaning syphon are often enough to control numbers. For more effective eradication, a number of options are available. Although snail killing chemicals can be purchased, these are often damaging to sensitive fish and can be lethal if dosage rates are not carefully calculated. Snails are often only temporarily controlled and need to be removed by hand after treatment. Although not specifically designed to target them, Discus worming treatments are often toxic to snails and can be used without affecting most species of fish. Other ways of removing snails include catching them with either specially made traps, tablets of fish food placed under an over turned saucer or by placing a well-washed lettuce leaf in the aquarium and removing them by hand. 

Less hands-on techniques involve using organisms that eat snails and these include a range of animals. For large aquaria, Clown loaches (Chromobotia macracanthus) can be used but are capable of out-growing most small home aquaria. Their smaller relatives the Zebra loach (Botia striata) and Dwarf Chain loach (Yasuhikotakia sidthimunki) are a much better choice for the smaller aquarium and both enjoy eating snails. Keep these social fishes in small groups. Other snail-eating fish include the nocturnal Talking catfishes and both Spotted (Agamyxis pectinifrons) and Striped (Platydoras costatus) species are available. 

For tanks where adding fish is not an option, the Assassin snail (Anentome helena) is a slow but effective means of controlling small snails and ideal for small aquaria. Once the tank is free of snails, the assassins will eat frozen food or meaty sinking pellets.

How do I calculate the volume of my aquarium/pond?

Ponds of irregular shape can be tricky to give accurate volume calculations for and often require some imaginative estimation. For an informal pond, imagine it as a rectangle and multiply the length x width x depth, then remove a percentage to allow for curves and planting shelves etc. if you are using metric measurements, a cubic metre is equal to 1,000 litres so convert your measurements into metres eg. 60cm = 0.6m and then multiply by 1000 to get a volume in litres. If you are measuring in feet and inches, a cubic foot is equal to 1,728 cubic inches, or 6.23 gallons. For circular ponds 3.142 multiplied by the radius squared will give you the surface area, which can then be multiplied by the depth to give volume before working out the capacity in the same way as above.

The best method of all is to time how long it takes to fill the pond with a hosepipe by first using a container of known volume to determine flow rate. If a hosepipe fills a 5 litre bucket in 4 minutes, a pond that fills in 80 minutes will contain 100 litres of water. It's easier than it sounds!

How do I work out the size of pond liner for the hole that I have dug?

Double the maximum depth and add it to the width and length.

Depending on how the edges of the pond are to be finished, allow some spare liner to either sit beneath coping stones or to form planting pockets. Often rounding the liner size up to the pre-determined roll width will give you ample to spare - for example, a projected liner size 4.4 x 5.6m can be rounded up to 5 x 6m giving an overlap of 0.6 and 0.4 metres respectively.

How often and much do I need to change my water and clean my filter?

A good general rule of thumb is 'keep your water clean and your filter dirty' and this is really the secret of successful fish keeping. Although good filtration will keep water crystal clear, it is important to remember that although clear, it may be full of the accumulated nitrates, phosphates, pheromones and other byproducts of daily life inside a fish tank. Properly carried out, a water change is always beneficial and if you follow a good regime of regular weekly 25% water changes your pets will prosper. Old water is great for fuelling algae growth and making your tank look tired as well as depressing the immune systems of your fish. Water change rates can be tailored to your stocking levels and feeding rates - messy fish such as large cichlids and goldfish thrive on large frequent changes, whereas Tanganyikan cichlids and reef tanks like smaller changes of around 10% at a time to ensure more stability.

Filters need to be dirty to work properly but there is still some regular maintenance jobs to be done. Biological media such as foams or ceramics need a rinse in water from the aquarium when they start to slow the flow rates appreciably. If you have the option of cleaning 50% of your media at a time, you can make this a more thorough clean but always use aquarium water and never expose mature media to chlorinated tap water. By contrast, chemical media such as carbon or phosphate removing resins become less effective when dirty, as bacteria will literally seal them and prevent them from working. Mechanical filter media such as floss, will work best when kept clean and changed at regular intervals.

Depending on various factors, a monthly rinse of filter media coinciding with that week's water change might be the ideal basis for a regular maintenance regime.

How can I get rid of blanketweed?

Like the daisies in your lawn, blanketweed thrives when conditions are to it's liking and although a weedkiller can knock it back for a while, if conditions remain the same, it'll soon return. The solution is to alter the water conditions to deter it, which means reducing the phosphates that it needs to grow. This can be accomplished in a number of ways and a holistic approach is often the most effective. 

To start, avoid using tap water which often contains high levels of phosphate and switch to rainwater. Fish food also contains phosphate, as it's essential in small quantities for healthy growth - check that you're not overfeeding and be prepared to carry out water changes in systems containing large fish and little plant life such as big koi ponds. Adding fast growing plants to compete can often make a difference and Watercress is the best of the lot, as long as you regularly trim it to prevent it from flowering and keep it hungry. Other plants that can help are the tender floating plants Water Hyacinth (Eichornia) and Water Lettuce (Pistia) which also shade out the algae but any plant growth will go some way to providing competition. Another natural control agent if used in sufficient number, is the Ramshorn snail (Planorbis) that eats algae without damaging plants. Products that reduce the available phosphate in the pondwater are well worth using, although they may appear slow to make a difference compared to the quick short-term fix provided by an algicide. As with greenwater, barley straw products can often help and whichever method you use, removing blanketweed to prevent it decomposing in the pond and re-introducing nutrients is a vital part of successful control. As blanketweed is often home to aquatic life, leave it beside the pool for a couple of hours to allow any creatures to escape before adding it to the compost heap or using it to mulch garden plants or vegetables.

Can I keep Goldfish in a bowl?

Lots of us can remember having childhood goldfish that were won from the fair, or bought by our parents who carefully swapped dead fish with identical replacements in the hope that we'd never notice. As a result, many people still regard a bowl as a suitable environment for a goldfish. Although the term Goldfish bowl seems as natural as Rabbit hutch, dog bed or cat flap, it belongs with terms like bull fight and mouse trap as labels which relate to animals in the wrong place at the wrong time. Goldfish will survive quite appalling conditions for longer than many fish, with the result that an animal which can live for more than twenty years in good conditions will endure a few years of poor water quality before finally succumbing. Now that we have the lecture out the way, lets look at the reasons why they're unsuitable.

Goldfish are potentially large (up to 30cm/12") messy pond fish that generate a lot of waste, both visible and invisible. Although most bowls are too small for their unlucky inhabitants, it is the lack of filtration that is the biggest issue rather than the size and shape. New generation fish bowls such as the Biorb provide the classic bowl shape with the essential ingredient of efficient filtration, which removes the toxic fish waste which otherwise poisons the fish, who is after all, unable to pop out to use the loo! Neglected fish bowls also develop these filter bacteria but have to start from scratch when the whole thing is cleaned out. The lack of space causes an otherwise healthy fish to become stunted and develop problems with internal organs which can remain unseen but deadly over time. To give your goldfish a happy and long retirement, move him into a nice garden pond or large aquarium where he can grow old gracefully.

There are a few species of fish that are perfect for small, unheated tanks or bowls with filters. Ask your local branch about the fantastic and versatile White Cloud Mountain Minnow.

How long do I need to leave my tank before I can add my first fish?

It is a good idea to leave a newly installed aquarium for a week to ensure that all the electrical equipment is working properly, the tank is free of any leaks and the water is free of chlorine and the supersaturated nitrogen than comes out of solution as bubbles in a newly filled aquarium. Although nothing looks quite as empty as a new aquarium, this time can be put to good use deciding which fish to add and in which order, as after all, it's much easier to put the right fish in than take the wrong ones out!

As a new tank is incapable of supporting fish until the filter matures, at this point you have a couple of options. A great method, if you have the patience, is to start the system maturing before adding any fish by using an ammonia source and a bacterial culture. This technique requires a test kit and close monitoring of peaks in both ammonia and nitrite levels before adding your first fish but has the advantage of taking your tank through the dreaded 'New Tank Syndrome' before you have any fish in there. Although this avoids exposing your new pets to damaging water quality problems, it can be a very frustrating process, sometimes taking weeks to complete. A more efficient way of accomplishing the same end result is to add mature filter media to the system and this is often available from our stores in the form of large chunks of ceramic media that can be placed in the aquarium and left to colonise the filter. A few manufacturers now supply bacterial cultures which can be added as the first fish are placed in the tank as a further option and this can make all the difference in the early days of your aquarium when you are most likely to encounter water quality issues. Note that whichever method you choose, bacteria need a source of fish waste to thrive and will die without either the addition of a small quantity of live fish, or further additions of ammonia.

The most established method of maturing a new aquarium is by the addition of a small number of hardy fish. The resulting ammonia and nitrite spikes are then observed and further fishes are added when these pollutants return to zero, with further gradual introductions taking place when tests prove negative for ammonia and nitrite. This tried and tested technique exposes fish to level of pollution that can prove stressful and is starting to lose favour now that better options are available. Whichever technique you choose, using a test kit is a vital part of setting up a successful aquarium.

How many lights do I need to grow plants successfully in my aquarium & how long should I leave them on?

As aquarists, we are lucky in that never before has such a wide selection of aquatic plants been available from all corners of the world. There are ferns from shady forest streams and tiny carpetting plants from sun-drenched flood plains. With such varied habitats, it is possible to find suitable plants for any aquarium. To duplicate the lush underwater gardens admired by many fish keepers, it is advisable to have at least two lamps above your aquarium fitted with reflectors to have a greater chance of growing most aquarium plants. Bright green foreground plants and many red plants have the greatest light requirement and are often grown under light intensities more commonly seen in marine aquaria containing corals.

As a general rule of thumb most plants will prosper in the 12 hour photoperiods seen in the tropics, although this may not be linked to outside conditions. For instance, if you are at work during the day it is perfectly acceptable to have your aquarium lights on from 11 am until 11 pm.

What is the smallest viable marine tank and what equipment do I need?

It can be said with all honesty that the better you know the rules, the more you can bend them before they break. Once you've run a large, successful marine tank, you'll find the greater challenge of a small tank much easier to manage. As a beginner, you'll find that the bigger your marine tank, the better. The temptation to cram lots of colourful fish into a tank is generally too much for novice marine keepers and is the reason for most failures as many people just can't resist adding that 'one last fish.' 

The heart of any successful marine aquarium is liverock and water movement. With this simple maxim in mind, a tank large enough to hold plenty of liverock and still have room for water is normally going to be of around 80-100 litres in capacity. Tiny tanks can be run with care and there are plenty of miniature fish and shrimps that can make a 'nano reef' a wonderful slice of nature in your living room. As small tanks are liable to rapid swings in temperature, salinity , etc., they need much closer monitoring. After all, the phrase 'a drop in the ocean' sums up the stability of the environment that these creatures come from.

If you fall under the spell of Nemo, a good guide line is a tank of at least 80 to 100 litres, as much liverock as you can afford, a protein skimmer and much of the equipment needed for tropicals. The systemised packages available are probably your best option and are designed to be user-friendly. Bear in mind that although messier than corals and other invertebrates, the fish themselves are often easier to keep. For example, virtually all the common clownfish you will see are captive bred in hatcheries, love people and fish food and have no idea that anemones even exist. By contrast, anemones need perfect water quality, high intensity lighting and expert care in order to thrive.

What should I do if I have a power cut on my aquarium?

First and foremost - don't panic! Most aquarium inhabitants can happily survive the slightly lower temperatures of a heated room for a limited time, so temperature is not a huge concern and can be boosted by adding sealed bottles of hot water if necessary. More critical is the water quality, as without filtration and water movement, these are the factors most likely to cause problems. Turn off the filter, as without oxygenated water flowing through the biological media, harmful toxins can build up that are discharged into the aquarium when the power is restored. If the power is out for an hour or more, remove some filter media and store it in a bucket with a little water from the aquarium to keep it moist as the bacteria will survive better out of water with exposure to atmospheric air. As the temperature will fall, cover the aquarium with a duvet, blanket or towel to slow heat loss and keep the fishes calm. However tempted you may be, never feed the fish if the filtration isn't working.

A real life-saving emergency piece of kit can be assembled using a battery operated air pump and a chemical filter such as Polyfilter, which will remove ammonia and nitrite thanks to the action of special resins. Other media such as zeolite, or even mature bio filter media can be added to an air-operated box filter. In the case of marine tanks, a battery operated air pump will ensure water movement around liverock, which will maintain water quality. In the absence of a better option, syphoning water from the tank and pouring it back in can help maintain oxygen levels if performed as needed.

The most important aspect of any loss of life-support equipment is the effect on water quality once feeding is resumed. I would recommend adding a filter bacteria starter to aid recovery and keep feeding to a minimum until both ammonia and nitrite levels are seen to be under control through regular testing. Be prepared to carry out a series of water changes in the days after a power loss and treat your tank as if it were the unstable system it was in the early days of maturation.

What is R.O. water?

Reverse osmosis, or R.O. water for short, is water that has been stripped of it's mineral content by a membrane that only allows pure water molecules to pass through it's matrix. The result is purified water that has very low hardness and pollutant levels and can be used for keeping demanding fish or marine invertebrates such as Discus or Corals. Although R.O. water is ideal for expert aquarists keeping delicate species, it is equally suitable for the average community tank - especially in areas where tap water contains high levels of nitrate or phosphate.

As R.O. water is so low in essential minerals, it is normally necessary to add buffering products to prevent problems with pH. Different buffers are available for freshwater or marine use and should be added before using the water in your aquarium.

How do I get rid of Nitrate?

Nitrate is a plant food and is normally rare in situations where plant growth is abundant such as ponds and natural water bodies - this is why it can be so deadly to wild-caught fish or sensitive species. In heavily planted freshwater tanks or marine aquaria with lots of liverock or a deep sand bed, some degree of balance can be achieved as long as patience is exercised in the early days of stocking. More usually, nitrate accumulates as a result of healthy biological filtration and is best removed by regular partial water changes. 

By performing a weekly 25% change you can limit the build-up of nitrate, although overstocked systems or those with large messy fish may need more frequent changes. It is always less stressful for both fish and fishkeeper to perform lots of small changes rather than a few large-scale ones and in the case of extremely high readings, daily water changes can be carried out until levels are under control. Remember that established fishes can tolerate levels that can be damaging to newly introduced livestock and when problems occur introducing new fish, this is often the cause.

It is well worth testing your tap water for nitrate, as this often contains concentrations that exceed acceptable levels and in this instance, it may prove impossible to run your aquarium using your mains water. In this case it may be necessary to investigate alternatives such as R.O. water or nitrate-removing resins, etc. Often a solution can be tailored to your aquarium after discussion with your regular store.

Why does my Goldfish keep swimming upside down?

As goldfish are mostly vegetarian by nature, they have a long gut to digest high-fibre foods. Although a diet based on dry food has all the vitamins and minerals to keep a fish in good condition, it can lack the fibre needed to ensure a healthy digestive tract and this means that slow-moving food generates gas as it passes through the gut, affecting natural buoyancy. By giving your goldfish frozen fish foods and access to plant material, you can make sure that your pet remains healthy inside and out.

To avoid other buoyancy issues with goldfish, it may be better to offer a pellet food to limit the amount of air that feeding fishes can swallow when taking food at the surface.

Why does my pond keep going green?

The microscopic green algae that swim freely in pond water are too small to be removed by normal filtration. They are the basis of a food chain which would naturally feed all sorts of small animals which, unfortunately, are eaten by fish and damaged by pumps. The algae itself feeds on the phosphate and nitrate that builds up in the system and these chemicals are often present in mains tap water. Using rainwater can help to slow down the rate of algae growth, together with the use of phosphate removers, barley straw products or in the case of wildlife ponds, adding live Daphnia - also known as water fleas. Adding more plants to compete with the algae and add shade will also help and is the foundation of the old 'balanced pond' concept.

For most systems an Ultraviolet Clarifier or UVC is the answer and can be guaranteed to ensure clear water when used correctly. These gadgets work by exposing the microscopic algae cells to lethal UV radiation, causing them to clump together into particles that can be removed by conventional filtration. These units only fail when flow rates are incorrect or maintenance is neglected. An important part of this regular maintenance is changing the UV lamp inside the unit and depending on design, this is necessary every six or twelve months.

How often should I feed my fish?

Apart from large, predatory species, fish are adapted to graze on tiny quantities of food throughout the day. With this fact in mind, most fishes will thrive when fed small portions two to three times a day and will soon learn to come and beg from their owner. Healthy fish should always be hungry and all food should be consumed within a few minutes of being added to the tank. Bear in mind that overfeeding can crash a system with a struggling or immature biological filter- test your water regularly to monitor conditions and if your fish don't seem hungry, check ammonia and nitrite levels.

Remember that even though the filter bacteria will transform harmful pollutants into safer compounds, these less harmful chemicals will accumulate at a rate equal to the amount of food added. Therefore the more you feed, the more water you need to change to keep these by-products under control.

Why are marine tanks generally more expensive to set up than freshwater ones?

Blame the fish. Most freshwater species inhabit changing environments where they’ve evolved a need to adapt to changing conditions. This makes them far more forgiving than marine creatures and to ensure they thrive, more hardware is required.

Although it couldn’t be any more ‘low tech’, Live Rock is a key ingredient in most set-ups and provides both filtration and decor. As this is sourced from marine environments it has to be air-freighted from its point of origin and this adds to the cost appreciably. Since the high-tech heydays of the eighties, marine aquarium keeping has become simpler but there’s still a range of expensive gadgets to make life easier.

Going back a little further, it was common practice to bleach dead coral and rock decor in order to combat the unsightly algae that inevitably took over. This is also a feature of aquaria where savings are made in the wrong areas and the system lacks the stability that comes with plenty of live rock.

As marine fish are generally considered the aristocracy of the aquarium hobby, it’s only fitting that their accommodation is suitably posh!

What type of fish would be best for a child’s first aquarium?

This is traditionally a job for goldfish which seem to have gained a reputation for being easy (and disposable!) pets. Perhaps your parents replaced your childhood goldfish when they died to save the heartbreak? Either way, the truth is that these are big, messy fish that need a large aquarium and are far more work to keep properly than more modestly-sized tropical fish. Trying to keep a goldfish in a small un-filtered tank or bowl involves exposing it repeatedly to poor water quality that could easily be termed cruelty. Not many people know that goldfish can easily live for more than twenty years when properly kept.

So, packing away the soap box, what are the best options? Goldfish still have a place but plan ahead and get a large aquarium, perhaps even consider a pond for them to move into after a few months in a spacious tank. A far better idea are small, colourful tropical fish such as Platys (Xiphophorus maculatus) which are domesticated and come in a range of colours, all happy to mix and easy to breed.

Whatever you decide, manage expectations and don’t make the mistake of promising ‘Nemo’ in a tiny Peppa Pig aquarium! Us fish folk are a hard-hearted lot and won’t put the emotions of children above the lives of aquarium fish when asked to deliver the impossible. Key to success is patience and an understanding of the problems that come from a new aquarium that lacks the right conditions to keep fish healthy. New tank syndrome is one life-lesson that children don’t need to learn, let alone pet fish.

Are real plants better for my aquarium than plastic plants?

From the point of view of the fish there’s very little difference in terms of shelter potential and for some species that eat live plants but appreciate hiding places they can be a massive help. They also serve to create a lush appearance where conditions may not favour the growth of real plants such as dimly-lit tanks or those with strong water-movement. Artificial plants can also be used alongside real plants to add a bit of variety.

It could be argued that artificial plants provide a surface for filter bacteria and like it or not, serve to trap detritus as well. What they can’t do is function in some of the amazing biological ways that living plants do. Healthy plants absorb pollutants produced by the fish population, such as ammonia, as well as the nitrates and phosphates that result from the functions of filtration and promote the growth of algae. Under sufficient lighting they also produce oxygen and remove carbon dioxide but it should be noted that this process is reversed overnight and oxygen levels can fall to very low levels in densely-planted aquaria with significant fish populations and low circulation.

Plants also have requirements and they need feeding to ensure they have all they need to function. Elements such as Iron are vital and a good aquarium plant fertiliser makes a huge difference to the growth of aquatic plants. CO2 supplementation can also help guarantee a healthy underwater garden.

Do I need CO2 to grow plants?

In short no, but not all plants are equally undemanding. Slow-growing, green plants such as Java fern (Microsorium) and Anubias can thrive in very simple set-ups but fast-growing or delicate species can be a pale version of their more robust CO2 nurtured selves.

Broadly speaking, the use of CO2 enables a wider selection of plants to be grown and makes less demanding types even harder to kill. Typically, the highly coveted aquascaped layouts seen in books, magazines and the internet tend to feature CO2 systems.

An additional, often overlooked benefit of CO 2 is that it gives rise to slightly acidic conditions that suit most species of fish that are likely to find themselves in a planted aquarium

Why do I need to add bacteria (e.g. Aquarium Munster’s Bactosprint) to my tank?

No matter how posh or basic your aquarium, all conventional filtration is powered by bacteria. This has always been the case and although the identity of the organisms responsible has been debated, their importance is beyond any argument.

The maturation process has always been a frustrating time for the hobbyist and a potentially lethal phase for aquarium fish. It’s even been dubbed ‘New Tank Syndrome’ and is the reason why many people lose heart and give up before the fun part begins. In recent times the practice of ‘Fishless Cycling’ has risen in popularity and is by far the best way to mature a new system prior to adding the first fish.

In the early days of ‘bacteria in a bottle’ it could be argued that available products were as effective as a chocolate hair-dryer and many were reluctant to embrace these new methods. The story today is very different and advances in the storage potential of bacteria make them a very efficient way to hasten maturation. Whether you use them together with a bottled ammonia source as part of a Fishless Cycle, or take the manufacturers at their word and add them before your first fish, they can take the suffering out of the equation for your new pets.

For more established systems they can be useful when adding new livestock, after cleaning or replacing filter media, or after using aquarium medications that may damage existing filter bacteria.

As we can see, good bacterial inoculants are a useful addition to most aquaria at one time or another and like test kits, should become a standard fixture in the tool kit of anyone serious about the welfare of their aquatic pets.

How does a protein skimmer work?

We’ve all seen foam on the beach or river banks and this is a natural phenomenon exploited by the technique of ‘Foam Fractionation’. This exploits a property of organic compounds (here comes the science bit...) which have both Hydrophobic and Hydrophilic elements. In simple terms they’re attracted to an interface between air and water such as an air bubble or the water’s surface.

A protein skimmer is a device that brings aquarium water into contact with a large concentration of air bubbles and although most efficient in denser, salt water they can also be used in some freshwater systems such as koi ponds. Standard components of a skimmer include air injection (via air pumps in older models or venturi intakes in more modern units) a contact chamber and a collection cup where foam accumulates and can be removed.

As this process removes organic pollutants before being broken down by bacteria, it has the effect of lowering waste levels and can be made even more efficient by using ozone. By effectively short-circuiting the normal oxidisation of waste it slows the accumulation of nitrates and phosphates which can have many benefits.

What is the difference between a UV steriliser and a UV clarifier?

The very simple answer to this is gapping. Sterilisers have a chamber that brings water and the organisms within it into very close contact with the lamp – this gives a much higher dose of ultra-violet radiation capable of killing parasites that would survive the lower doses used to kill algae cells in a clarifier.

Because of this difference in exposure, a steriliser will effectively function as a clarifier but may be more susceptible to fouling when large particles of waste are pumped through the unit. This is less of an issue for a clarifier that has a larger contact chamber and less restriction on solids passing through it. This is why most units designed for pond use are clarifiers and better able to cope with a dirtier environment.

What is the best gravel for my aquarium?

On the face of it this is a simple subject but it does have some unforeseen effects. Starting with particle size, large grades of gravel have large void spaces that can trap a lot of solid waste. This means that they will need regular maintenance with a gravel-cleaning siphon to avoid problems such as a build-up of nitrates and phosphates. Heavier gravel is harder for fish to move (or swallow!) and can make very effective decor so don’t let this put you off. At the other extreme, sand and fine gravels are more likely to allow wastes to remain visible on the surface where it can be harder to ignore and again, siphoning is the answer. Aquatic plants are generally adapted to grow in anoxic mud and prefer fine substrates which also serve to keep any growing mediums isolated from the aquarium water.

Geology is another factor in choosing the right gravel and those containing limestone or coral can affect water quality. For this reason, soft water habitats where a low pH is desired, such as discus tanks, rely on selecting a lime-free gravel. Conversely, fishkeepers in soft water areas who keep hard water species such as Rift-lake or Central American cichlids may want to use coral or limestone gravels that help ensure the alkaline water that these fishes need.

How do I know if my fish are ill?

The answer to this is observation. By knowing what’s normal behaviour and deportment for your pets you can tell if they’re behaving strangely. For instance, swimming upside-down is normal for certain catfish, reef fishes and cichlids but definitely a sign of problems in goldfish!

Obvious signs of ill-heath are clamped fins, increased gill rates, flicking against decor and lethargic behaviour. The very first response to these symptoms should be a water test and often this will reveal the cause of the problem – after all, your pets will be very keen to die of old age and have immune systems that will combat disease when environmental conditions allow. Once you’ve ruled this out, take a photo on a camera phone and seek advice from an experienced member of shop staff. As treatment can be different depending on the pathogen involved, adding a medication ‘just in case’ can delay the use of a more effective cure after a proper diagnosis.

Why are my fish not eating?

If you’ve added a recognisable source of food for the species concerned then the answer is usually stress.

The first thing to rule out is water quality, most fishes will quickly lose their appetites when exposed to ammonia or nitrite or inappropriate water chemistry.

It’s also fairly normal for anxious fish to prioritise security over foraging, in other words a new fish will often be nervous of entering open water to feed – especially in the case of reef fish or shy, nocturnal tropicals.

Some wild-caught fish have very firm ideas about what’s edible and at one extreme are the species that only feed on live fish or corals. A bit of homework will help you identify dietary specialists such as Butterflyfish and Filefish that only eat living Acropora corals for example.

Why are my goldfish changing colour?

Goldfish are a domesticated form of a brown wild ancestor and their familiar bright colours are a result of many generations of selective breeding. 

A glimpse into their original colour can be seen in many goldfish ponds when the dark brown fry are spotted amongst the plants in late summer. This camouflaged baby colour protects them from their many predators and as they grow larger they start to change colour. This tends to be linked to temperature and warmer conditions promote a much earlier shift from brown to red.

The genes responsible for this switch can lead to further colour changes and some of the more common ones are black fish turning red and red fish becoming silver with age.

What is the best size aquarium to start with?

This used to be an easy question to answer and a lot of the advice still holds true today. A larger tank tends to be more stable and holds more fish – this can be important when some of the most common mistakes involve overstocking or rushing the maturation phase. Aggression between tank mates is less of a problem as tank size increases and species which need to be maintained in shoals to avoid compatibility issues are more readily housed. Many people find that their new aquarium is the gateway to a new and consuming passion and quickly wish that they had more room to house their collection.

With the advent of improved technology and the fashion for smaller tanks, it’s only fair to state their biggest advantage: they’re easy to work with. Consider the advice of having to perform a weekly water change of anything up to 25%, in a large aquarium that’s a lot of heavy water to move about, whereas a smaller system can be serviced with far less time and effort.

That said, after many years of dealing with vast numbers of passionate fishkeepers, most never seem to have enough room for the large selection of interesting species available to this fascinating hobby. Therefore, we would always recommend going for the largest possible aquarium that you can house and afford!

Why does my anemone move around my tank so much?

Anemones are fairly mobile, it enables them to find the perfect environmental conditions to thrive. It also allows them to take shelter to avoid extreme events such as storm surges that could otherwise damage their delicate bodies. 

This means that they will often drift around as they would in nature until they find themselves somewhere more suitable. Sadly this means they may encounter hazards such as powerheads, overflows and other corals within the aquarium.

As there’s a number of species with differing requirements, researching the one that will thrive best in your system can minimise the need for it to feel dissatisfied. Some of them prefer a deep substrate, others thrive best away from corals and all of them tend to have light requirements similar to light-loving corals.

What are the best tips for taking care of my fish while I’m on holiday?

Fish are generally quite easy to fit around holiday absence. However it pays to do some preparation first though, and having someone who can pop in once or twice a week can be very useful. Without a doubt, over-feeding is the biggest threat to an aquarium or pond left in the hands of a novice.

If you have a human caretaker available, show them the normal state of the filters and life-support equipment ahead of time and leave the phone number of your favourite fish shop near the tank. Hide the main containers of food and leave labelled portions to make feeding issues less likely. Consider using tablet foods to simplify the quantities offered, or in the case of frozen foods, use an ice cube tray with portions frozen into blocks of water.

Leaving an aquarium unsupervised is also an option and automated feeders can be used to keep home-alone fishes fed. Install such units a few days before departure so that settings can be adjusted and the correct quantities used. If in doubt, under-feeding is far more healthy than over-feeding and intervals such as weekends can be left without any food provision. Old-fashioned plaster-based dissolving food blocks are still available, as are their modern equivalents which tend to have less impact on water parameters such as KH.

Ensure that you carry out routine maintenance such as cleaning filters or performing water changes before you go to avoid any complications or failures due to blocking etc.

How do I stop predators eating my pond fish?

There's no shortage of creatures who regard your pond as a feeding station, a bit like a bird table. For species such as herons who have evolved to spend hours hunting brown fishes in murky water, the combination of clear water and colourful fish is a dream come true! Other creatures that pose a threat include cats, foxes, crows and humans to name a few.


Initial pond design can play a factor, such as vertical sides rather than shallows to prevent wading predators but protection falls into two categories - barriers and devices.


In the first category, cover nets are really the beginning and end of the solutions and although not as attractive, they are probably the most effective. If a pergola or other structure is used above the pond, strands of fishing line can be placed at regular intervals to limit the wingspan of any visiting birds. 


As you can imagine, more hi-tech solutions are now available including those that spray water or flash and emit scary noises. There's also a range of other solutions including the good old plastic herons, although these are best used by pond keepers with a good aim and a strong throwing arm for best effect.

What are gill flukes and how do I get rid of them?

Gill flukes (Dactylogyrus) and skin flukes (Gyrodactylus) are common parasites that affect fishes. Like popular community fish, they are split between livebearers and egg layers, but that's where the similarities end.


Despite the given names, they are both likely to be found on the gills or skin and although often found in small numbers on healthy fish, large numbers can be very debilitating. Flukes are often the cause of damage that leads to bacterial secondary infections and, being microscopic, are hard to detect.


Like most parasites, controlling background waste levels and maintaining good water quality is important in reducing populations and ensuring fish have a healthy immune system. As flukes are often the root of ulcers and other secondary infections, treat for flukes before treating with antibacterial or antifungal medications. A number of treatments are available for flukes, those containing Praziquantel are the most effective.

How do I know if my water is too hard or too soft for my fish?

In a word: Homework.


It's fair enough to say that your local fish shop is likely to use tap water to fill their tanks and on the whole, captive-bred tropical fish are a hardy and adaptable lot. Some groups of fish are rather less forgiving, though and Rift-lake Cichlids and Discus are examples of these more demanding specialists.


By testing the hardness of your tap water you can easily determine its suitability for use and select your fish to suit. Sod's law generally dictates that hobbyists with hard water want to keep soft water fish and vice versa. If that's the case then using RO water can free you from the tyranny of tap water completely and buffers can be used to make the softest water suitable for even those Mexican natives that are used to swimming in liquid rock! 


What is a “Tankbuster”?

"Tank busters" are big, powerful fish unsuitable for the average domestic aquarium. If you've seen a species on TV being held by a celebrity angler, it's fair to say it meets the criteria and some of these are all too commonly available. Some of these mighty beasts, such as the big catfishes, are predators with enough strength to crack a tank with the muscles evolved for fighting river surges.

Many of the more commonly encountered tank busters are food fish, mass-produced on fish farms for growing-on in ponds. This means they're very cheap and can tempt the unwary when encountered as cute babies in stores that should know better. Pangasius catfish are a great example of this and can be found in unethical fish shops as well as supermarket fish counters. Like all tank busters, this fish makes a beautiful and long-lived pet in appropriate conditions for those able to provide them. Realistically, these facilities are rare outside zoos or public aquaria and they struggle to re-home fish that may live thirty years and grow a metre or more in length.


Sadly, as our systems include larger stock tanks than many other outlets, we often find these homeless fish on our doorstep, or rescued from customers who either didn't do their research or received poor advice from other retailers. Take a look at the Big Fish Campaign for details of the most common species in this category.

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