Sturgeon

Care

Sturgeon is the common name given to any of the 25 species of primitive fishes belonging to the family Acipenseridae, which inhabit the subtropical and sub-Arctic coastlines, lakes, and rivers of Eurasia and North America. This family is further split into two sub-families, together comprising 4 genera: Acipenser, Huso, Pseudoscaphirhynchus, and Scaphirhynchus. The earliest fossil records of Sturgeon date back to the Triassic period, some 250-200 million years ago, and their morphological characteristics remain largely unchanged. All species of Sturgeon grow very large, and are known to live for decades, with sexual maturity typically being reached between 10 and 20 years. The body is elongate and scaleless, with 5 rows of angular bony plates (scutes) providing armour. The rostrum is flattened, and the caudal fin is heterocercal, meaning the vertebrae extend into the upper lobe of the tail, making the top lobe longer than the lower - as is often seen in sharks.

When it comes to keeping Sturgeon in a pond, there are many specialist requirements that need to be addressed if they are to thrive long-term. It may seem obvious, but it is extremely important to provide these fish with as large a pond as possible from the outset if they are to reach their full growth potential through exercise gained by swimming. The pond should be at LEAST 4ft/1.2m deep (6ft/1.8m or more is better) and also as long and wide as possible to give a large surface area for oxygen exchange. Ideally the floor will be mostly flat without too many sloping areas, in order that the Sturgeon may feed easily. Sturgeon have a toothless, vacuum-like mouth on the underside of the head, with 4 sensory barbels and taste buds on the outside of the mouth. The mouth is set back from the tip of the long rostrum, and as they generally like to run the barbels and taste buds over the substrate in search of food that has sunk to the bottom, this non-visual feeding behaviour will be facilitated by as generous a flat pond floor as possible. Whilst these fish are native to colder climates, it is also important to consider the depth of the pond because of seasonal temperature fluctuations; rapid changes in temperature (rather than gradual changes) may distress the fish. The deeper your pond is in proportion to the surface area, the less susceptible it will be to swings in temperature. A larger volume of water is also, of course, much more stable in terms of water parameters than a smaller one. A pond heater is definitely worth considering for the winter months for those in colder climes as it will help keep temperatures more steady. There is much that should be planned out thoroughly beforehand, such as location, size, shape (formal or non-formal design), materials (liner, concrete etc), and the need for oversized filtration (gravity fed/pump fed etc) and a power supply. A vital consideration for a healthy pond is choosing a suitable location. Try and choose an area that is of south/west aspect and which is in medium shade, receiving approximately 4-6 hours of sunshine per day. An unshaded north facing garden is far from ideal. Ensure the site is not directly under the shade of trees as falling leaves, and the invasive root system of some species can become a problem. Sufficient area must be left for a large filtration system (with a size at least 1/3 the surface area of the actual pond), and this is an area that shouldn't be overlooked in the haste to construct the pond. A filtration system cannot be too big but it can cause a lot of problems if it is too small! Experts are always on hand at your local Maidenhead Aquatics to discuss your options when it comes to filtration for a large Sturgeon pond. Other aspects to think about are whether you wish to incorporate some form of waterfall or fountain, which will aid aeration during warmer days. Sturgeon have an enormous requirement for dissolved oxygen, and you will need to consider additional aeration for the pond during the summer when the water temperature rises and dissolved oxygen levels decrease. Extra pumps/powerheads will help to incorporate more oxygen (ensure the surface of the water is rippling in places), and a hefty pond air pump is an essential piece of kit to have on hand in the case of an emergency. Once the pond has been constructed, it should be filled with dechlorinated tap water (rain water is unsuitable for the first fill as it lacks the necessary minerals).

Unlike other ornamental ponds, the Sturgeon pool should not contain plants. This is because they can easily become entangled in overgrown vegetation, with possible disastrous consequences due to being unable to reverse because of their fixed, paddle-like pectoral fins. The same applies to outbreaks of blanketweed, which must be kept in check to avoid these clumsy swimmers from becoming caught up. Even the largest of specimens can struggle to free themselves from the these surprisingly strong threads. So prevention is key when it comes to blanketweed: ensure the filtration is oversized, that the pond does not receive too much direct sunlight, that the fish are not being overfed, and that regular partial water changes (not just top ups!) are being carried out. Regular partial water changes help to reduce nitrate (which feed algae) and will replace essential minerals. We would recommend that the pond water is tested on a weekly basis as this will alert you to the first sign of any problems. UV clarifiers can help if green water becomes an issue; this can look rather unsightly and make viewing the fish difficult. Not only will this spoil your enjoyment, but any fish that might have injured itself or is suffering from parasites, for example, will remain hidden from your attention. Ensure that you do not overstock your pond, making sure you allow for the eventual size of your Sturgeon, and always quarantine new purchases. Please be aware that many pond treatments are unsuitable for use when Sturgeon are present, due to their scaleless skin - this includes most algaecides and a number of medications (particularly those based on copper or formaldehyde). Always check with the manufacturer before use.

Currently the status of this species' native wild relatives is critical.  As with any pet fish, it's important never to release sturgeon into the wild where they can impact their wild kin.

Feeding

Carnivore that requires specialist sinking foods specifically formulated for Sturgeon, that are high in fish meal/shrimp meal protein and easily digestible. If other fish are present in the pond, always feed them their usual food first in order to keep them occupied, then offer the specialist sinking food to the Sturgeon. This will help to prevent the other fish from greedily consuming all the Sturgeon food before it reaches the bottom. It is very important to ensure the Sturgeon are not being outcompeted at feeding time, and equally important that they receive a specially tailored diet. As Sturgeon have short guts with limited capacity, a number of small feeds per day is much more beneficial than one large feed, but do be careful not to overfeed. During the autumn/winter months, Sturgeon will continue to feed down to 4 °C and it is important that they continue to receive small amounts of food (even when other fish in the pond aren't feeding) in order to prevent starvation. However, do remove any uneaten food promptly.

Breeding

In the wild, these fish are known to undergo long migrations, spawning during the summer in the main, deep river channels with vigorous current and high O2 level, over stony and gravelly substrates. Post-fertilisation, the membranes of the eggs (which may number several hundred thousand) become increasingly more sticky and this allows them to adhere to the substrate when they come into contact with it. At 10-15 °C, the eggs would be expected to hatch after approximately 5-10 days, with larval development taking a further 14 days or so. Sturgeon do not necessarily spawn every year, because they require a very specific set of environmental conditions which are not always met.