Chin tetra, Piabucus sp.

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Matt Clarke looks at the Chin tetra, a recent import which appears to be a member of the Piabucus genus.

Common name: Chin tetra.

Scientific name: Piabucus sp.

Origin: Imported from the Rio de la Plata, Argentina.

Water: Apparently from a warmer part of Argentina in neutral, soft water.

Size: Have grown from 5 cm/2" to just over 10 cm/4". Given the sizes of other Piabucus, this is probably the maximum for the species.

Diet: Pete Liptrot says that Piabucus is one of the few fish that will eat the filamentous red algae Compsopogon and Adouinella.

Aquarium: Go for as large a group as you can afford and keep them in a spacious aquarium, furnished with a soft, sandy substrate (most live in muddy streams). Keep them alongside similarly peaceful fish.

Notes: Bolton Museum Aquarium aquarist Pete Liptrot kindly identified these as a Piabucus for me. These very unusual characids are members of the subfamily Iguanodectinae, and there are only three described species, all of which are extremely rare in the hobby.

Pier Aquatics, who imported these, reckon this one is a new species.

Similar species: There are three described species: Piabucus dentatus, P. melanostoma and P. caudomaculatus. P. dentatus can be ruled out, as it comes from the north-eastern coastal region of South America, where it occurs in French Guiana, Suriname, Guyana and Venezuela. Unlike caudomaculatus and melanostoma, it also lacks black pigmentation on the chin.

P. caudomaculatus is currently known only from Bolivia. P. melanostoma is more widespread, and has been reported from western Brazil, Bolivia, Paraguay (just north of Argentina), and the Peru/Colombia/Brazil border.

The original description of P. caudomaculatus describes a similar-looking fish, but it lacks the adipose fin seen in this species, which rules it out. That leaves only P. melanostoma, or the possibility that this is undescribed.

P. melanostoma has an adipose, 11 dorsal rays, 44-46 anal rays and 82-87 lateral line scales.

Availability: These were among dozens of very unusual species we recently spotted for sale at the excellent Pier Aquatics in Wigan (01942 236661).

Price: Around 4.95.

This article was first published in the June 2007 issue of Practical Fishkeeping. Pictures by Neil Hepworth.