Trachycorystes trachycorystes

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Matt Clarke on a newly imported driftwood catfish from the Trachycorystes genus - which is nastier than it looks.

Common name: Black driftwood catfish

Scientific name: Trachycorystes trachycorystes (Valenciennes, 1840)

Origin: This species has been recorded from Brazil and Venezuela. This fish was imported from Peru.

Size: According to museum records T. trachycorystes can reach 35cm/14".

Water: No precise data. These were doing fine in moderately hard water, but the species is really an acidophile.

Diet: This is a predatory fish and probably feeds on fish and crustaceans, such as shrimps. It should take frozen shrimp and chunks of frozen fish.

Aquarium: Although auchenipterids don't have a reputation for being particularly nasty, this one is a notable exception. According to Richard Hardwick, this one has the personality of a Hemibagrus wyckii on an off-day and will try to bite your hand if you put it in the tank. Consequently it's a fish for specialists and should only be considered for a species tank, or one containing much larger tankmates, such as cichlids. Given the large size, a 150 x 45 x 45cm/5' x 18" x 18" tank is needed for an adult. As the name suggests, this fish is found among submerged branches, so furnish the tank with lots of bogwood to provide daytime shelter. It sleeps all day, but becomes active at night and spends much of its time swimming about in search of food so provide it with plenty of space to swim around.

Related species: The Trachycorystes genus contains three other species: T. cratensis from Brazil's Rio Granjeiro; T. obscurus from the Rio Essequibo basin in Guyana, and T. porosus, which is only known from aquarium specimens and has no collection locality data at present. There's also another called T. sp. "Megamouth" (huge mouth, white ventral surface) but it's not known whether this is one of the other three.

Notes: This genus has very unusual reproductive traits. Sperm are introduced into the oviduct before the eggs are mature and the female uses the stored sperm to fertilise the brood without the male being present. The genus is sexually dimorphic as males have modified anal fin structures to allow them to internally fertilise the females.

Availability: Very rarely seen for sale in the UK and quite sought after. This pair was spotted for sale at Wharf Aquatics in Nottinghamshire (01773 861255). They were imported by Tom Halvorsen Ltd (0797 709 8127).

Price: On sale for £300 for the pair, or £175 each.