Care
The diminutive SumatranMiniature Cyprinid (Paedocyprisprogenetica) is currently recognised as the world's smallest fish species.It also held the record of the smallest known vertebrate for a time until a small species of frog from Papua New Guinea measuring just 7.7mm was described in 2012. These minuscule shoaling fish are known from slow-flowing, blackwater streams and pools with very low pH and negligible hardness, in ancient peat swamp forests. They tend to inhabit the deeper, cooler water layers in the lower half of the water column, fairly close to the bottom. Observations have found that they much prefer shady waters and are found only in areas that are shielded beneath the forest canopy, being absent from more open areas that are exposed to direct sunlight. These fish are an ideal choice for small, heavily planted aquaria. The tank must be mature and have a myriad of hiding places amongst driftwood and thick vegetation, which should include floating species to help diffuse the light. Broad-leaved plants can be beneficial to encourage spawning(see below). Filtration should be efficient, but water movement gentle. It is highly recommended that RO water is used and this is filtered through aquarium peat to help reduce the pH. The addition of Dried Indian almond leaves (Terminalia catappa) or blackwater extract could also be advantageous. The tannins released will impart a natural tea colour to the water; this will not be harmful to the fish, and in fact will result in them showing their most intense colours. These peaceful fish can be rather timid, so a decent-sized group of 12 or more will help to give them confidence. They are really best off housed in a species tank environment, but if tankmates are a necessity, ensure that they are also small and placid; for example, small Caridina/Neocaridina shrimps or Eel loaches (Pangio spp.). Much attention must be paid to water quality since Paedocyprisprogenetica are somewhat delicate and do not tolerate elevated nitrates or swings in water chemistry. Acclimatise very carefully. Unfortunately, their natural habitat is at great risk from logging, plantations, and forest fires, but is yet to be evaluated for red list status.
Feeding
Offer tiny foods such as baby brine shrimp (hatched from decapsulated brineshrimp eggs), rotifers, crushedflake, fry foods, and micropellets.
Breeding
This species has only been bred a handful of times in captivity and would make a wonderful breeding project for the experienced hobbyist. When ready to spawn, male fish swim to the underside of a broad leaf to establish their breeding territory. At this time, there may be minor scuffles between rival males as they vie for preferred spawning sites. This behavior has been noted to begin when the morning sunlight hits the aquarium glass or when the tank lights first come on. When spawning territories have been established, the male fish will position itself in an inverted position under the leaf, its belly facing the underside of the vegetation(his abdomen will be in contact with the leaf, but his caudal and pectoral fins will not be). He will remain in this position for a time, occasionally moving slightly up and down, and then after a short interval, and often when females are in the close vicinity, he will detach himself from the leaf and resume the normal swimming position, before darting back into place beneath the leaf (this repeats every couple of seconds). When he swims back to the underside of the leaf, he positions himself so that an iridescent spot on his head faces the female. Eventually, a willing female will join the male at the same spot underneath the leaf, also inverted and positioned side by side with him. Mating is extremely quick and the exact method is not yet clear. Single spherical, translucent, adhesive eggs are deposited on the underside of the leaf, and these take approximately 30 hours to hatch at 27 °C. Newly hatched larvae are minuscule, measuring just 1.3mm in length, and lie motionless, attached to the underside of the leaves or on the sides of the aquarium glass. Raising the mini sculefry is extremely challenging because of the microscopic foodstuffs required.
