Matt Clarke looks at the pimelodid catfish Megalonema platycephalum that's currently on sale in the shops as Brachyplatystoma sp. Peru.
Scientific name: Megalonema platycephalum Eigenmann, 1912
Origin: Collection records show that the species has been collected in Ecuador and Guyana on the opposite sites of the northern part of South America. This beogeography suggests that species is likely to occur in Colombia, Venezuela and possibly northern Brazil, too.
Size: A relatively medium-sized pimelodid, reaching around 30cm/12" in length according to museum data.
Diet: Probably a predator of small fish and crustaceans, but aquarium fish apparently accept a range of frozen foods quite readily.
Aquarium: These are somewhat more manageable than many other largish pimelodids, so a tank of 120 x 60 x 60cm/4' x 2' x 2' will suffice as a minimum, although more space would be beneficial. Little has been written about their habitat, but they're probably found in large, flowing rivers, so expanses of sand and large water worn rocks would suit, along with the odd bit of bogwood to provide shelter.
Notes: There are currently six species in the rarely seen pimelodid genus Megalonema. Megalonema argentina, M. pauciradiatum, M. platanum, M. psammium, M. xanthum and M. platycephalum. M. argentina has a southerly distribution, M. pauciradiatum is found in central Paraguay, M. platanum is found from Paraguay and south to Bolivia and Argentina, and M. psammium is found in Venezuela. M. xanthum is found in Colombia and Venezuela, so its range might overlap with that of platycephalum.
Identification: It has been reliably confirmed by Heok Hee Ng that these are a species of Megalonema, as Brachyplatystoma typically have smaller eyes. The species has previously been imported to Germany under the name Piramutana piramuta.
Availability: These fish were imported by Tom Halvorsen Ltd (0797 709 8127) under the name Brachyplatystoma sp. Peru and are currently on sale at Wharf Aquatics in Nottinghamshire (01773 861255). These are pretty rare. It's the first time I've personally seen Megalonema for sale in the UK.
Price: On sale for 115 each.