Matt Clarke on an unusual catfish from India and Nepal, Batasio batasio.
Scientific name: Batasio batasio (Hamilton, 1822)
Origin: India and Nepal.
Size: Usually around 8cm/3", sometimes an inch or so bigger.
Water: Best kept in soft, acidic water. Keep in cooler subtropical temperatures around 20-23C/68-74F and ensure that the oxygen levels remain high.
Diet: Sometimes a fussy eater. Try offering frozen bloodworms, artemia and daphnia, if dried foods aren't taken.
Aquarium: These rheophilic catfish are found in relatively cool, running water. They can be kept in groups alongside other fish from the region. Danios, barbs and Barilius would make interesting tankmates and many would appreciate the flow these catfish prefer.
Breeding: The fish can be sexed. Females become fat with eggs when in good condition, while males have a genital papilla. At least one species, B. tengana, has been bred in captivity.
Identification: According to recent work by Ng and Edds there are now 10 species in the genus, including: batasio, macronotus, tengana, affinis, dayi, merianensis, havmolleri, travancoria, B. tigrinus, elongatus and sharavatiensis, with an eleventh fish, pakistanicus, also tentatively considered a member. B. batasio has a distinctive lateral stripe, shared only with travancoria and the recently described macronotus, as far as I am aware.
Availability: These aren't amazingly rare, and are probably the most common in the genus, but they're still rarely sold. These were imported by wholesaler Tom Halvorsen Ltd (07977 098 127).
Price: Around £10 each.