Rosy bitterling, Rhodeus ocellatus ocellatus


Matt Clarke looks at a species of bitterling that isn't restricted by Defra controls.

Scientific name: Rhodeus ocellatus ocellatus (Kner, 1866).
Common name: Rosy bitterling.
Origin: Mainly found in China but also in Taiwan, in both ponds and inland rivers.
Size: Males can hit 7cm/2.5”, females 5cm/2”.

Water: Subtropical, so fine in an indoor unheated aquarium if not too cold or too warm — ideally 18-24C. Neutral or slightly alkaline conditions are preferred, but these fish readily adapt to harder water.
Diet: Mine take dried foods readily, as well as frozen bloodworms and Artemia.

Aquarium: Being shy they appreciate shelter and should only be kept with other quiet fishes. I keep six alongside various Rhinogobius gobies, Amano shrimp and Porcupine nerite snails in a Taiwanese biotope aquarium with a sand substrate, large artificial rocks, spindly bits of wood and straight vallis.

From a distance, you could confuse this fish for the Neon dwarf rainbow, Melanotaenia praecox. Males develop a lovely metallic blue sheen as well as an orange chest and pink fins.

Breeding: These spawn in mussels. Females develop an ovipositor or tube with which to insert eggs into the inhalent syphon of the mussel. The male releases his sperm and they are sucked inside to fertilise the eggs. The fry remain inside the mussel until hatching.

Taiwanese mussels have been imported but are proving difficult to keep, so the chances of spawning these bitterling are hampered.

Notes: There are two subspecies of Rhodeus ocellatus: R. ocellatus ocellatus and R. ocellatus kurumeus — the latter being found in Japan but critically endangered.
Availability: I bought mine from The Waterzoo in Peterborough, but they have also been on sale elsewhere. These fish are classed as tropical so not restricted by Defra controls.
Price: Around £6.95 each.

This item first appeared in the July 2010 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.