Bolton Aquarium is world's first to breed tiny fish

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Aquarists at the Bolton Museum, Art Gallery and Aquarium have become the world's first to spawn one of the world's tiniest fish species - the miniscule Danionella translucida.

The tiny transparent cyprinid Danionella comes from Myanmar (formerly Burma) and has never been bred in captivity before. It reaches just 12mm in length, with females topping-out at around a centimetre, making it one of the world's smallest freshwater fish species.

The species is so small and delicate that it is rarely exported and has been kept by very few fishkeepers around the world. Very little is known about the biology of the species as it is too small for scientists to study in the wild.

Aquarium Development Manager, Pete Liptrot, told Practical Fishkeeping that they acquired the group of Danionella from nearby specialist retailer BAS and had been keeping the fish in an aquarium behind the scenes for the past six months with an eye to putting them on public display:

"We've seen four so far, three we thought were freshly free-swimming until we saw one that really was obviously just free-swimming because it was absolutely tiny in comparison (so the first three must actually be several days old, in spite of the fact that they are as small as newly-hatched Melanotaenia fry).

"We're going to have to use very fine powdered foods and infusoria on these, maybe even green water if we get any number of them, the one tiny one must be almost as small as an Iriatherina fry. We assume that the three have survived because they are in a mature tank and so were able to find enough micro-organisms to survive. We watched the larger three with freshly hatched artemia and they chased them but they were too big for them to manage, we tried microworm with pretty much the same result."

The Aquarium said that species as small as Danionella can go extinct through habitat destruction without people realising. A number of tiny fish, such as the recently described Paedocypris species, have been discovered recently in south east Asia in very vulnerable areas.

Bolton's aquarist team, Pete Liptrot and Paul Dixon are currently growing-on the young Danionella in their research area so they can maintain better environmental control to ensure that the survival rate for the fry is high.

The Bolton Museum, Art Gallery and Aquarium said: Once the aquarists are confident that the fish are breeding on a regular basis they will be moved to a display aquarium for the public to see. However, if anyone is interested in seeing the fish in the meantime they can contact the aquarium in advance and staff will be happy to arrange a time for this to happen.

For more information contact the aquarium on 01204 332200. Bolton Museum, Art Gallery and Aquarium is situated in Le Mans Crescent, opposite the Town Hall. Opening times are 9am to 5pm, Monday to Saturday and admission is free.