#bitterlings

[antiqueanimals]

Fishes. Written by Gwynne Vevers. Illustrated by Alan Jessett. 1976.

[antiqueanimals]

Grzimek's Animal Life Encyclopedia. Volume 4: Fishes I. Illustration by Friedrich Reimann.

[aquariuminfobureau]

In past days, it was possible to obtain, at least for aquarists in the UK, at least two species of bitterling, Bitterling, which are cyprinids of the genus Rhodeus, are of interest for their fascinating life cycle, one that is based on depositing its eggs within a freshwater mussel, as a protected environment for the growth of its offspring. Sadly the bivalve is difficult to care for in aquaria, and almost always dies. So it is very difficult to breed bitterlings in the home aquarium, and it should not be attempted by those unable to respect and care for the mussel, that must live with the breeding fish. Bitterling possess a very large, tubular ovipositor, for the purpose of positioning their eggs inside the living mussel. Indeed the size of this structure, relative to the length of the bitterling, is visually striking.

One of the species traded, was R. ocellatus, the rosy species from East Asia. In fact the species once had a much smaller range, for it was once restricted entirely to the island of Taiwan. Centuries ago, this species was introduced to mainland China, as well as Korea and Japan. Since those days, populations have invasively colonised quite far flung locations, but the latitudinal range of this species in Asia, ought to inform us as to its tolerances. For it is established in Beijing just as it is in Hong Kong, although the latitude of Beijing suffers far more severe winters.

Rosy bitterlings are common in vegetated farm ponds and irrigation channels, and they grow to around 9 centimeters, or under 4 inches long. These species display sexual dimorphism, with the females growing to only a mere 2/3 of the length of their male counterparts. Originally this species preferred lakes, natural ponds, and sufficiently slow moving rivers. But now it is quite synanthropic, and is considered a nuisance on fish farms, where they are believed to compete with the juveniles of the cultivated species.

Rosy bitterlings appreciate a rather neutral pH, and a temperture range suited for a warm temperate to subtropical fish. 28 degrees centigrade might be regarded as a good upper limit duriǹg the summer season, dropping to a few degrees below zero, in the wintertime. Although this fish has become established long ago, in some regions where the winter air temperature is often below freezing, most of its populations do not. And it is unnecessary to expose this fish, to such low winter temperatures. Although a winter drop in temperature, is natural for these bitterlings.

When intending to accommodate R. ocellatus, their aquarium should be well planted, and the provided substrate fine, to reflect their natural habitat. Other peaceful fish can cohabit with bitterlings, although they will need to share its requirements as a non-tropical species. Like a great many cyprinids, R. ocellatus naturally form schools with their conspecifics. Their diet is recorded in the wild, to be omnivorous with a vegetarian tilt, including both algal and small arthropod components, but diatoms are their primary food source in the wild.

[little-forget-me-not]