The ripsaw catfish

The ripsaw catfish (Oxydoras niger) or cuiu cuiu is a species of thorny catfish native to the Amazon, Essequibo and São Francisco basins in Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela. This species grows to a length of 100 centimetres (39 in) SL and weights up to 13 kilograms (29 lb).

This species is a minor component of local commercial fisheries. Has lateral thorns that can damage a potential predator or handler. It feeds by shifting through sand and detecting eatable parts with the taste receptors in the roof and floor of his mouth.

O. niger occurs over mud in streams and lakes.This species feeds on detritus, chironomid and ephemeropteran larvae, and crustaceans. O. niger is a popular aquarium fish species.

This species grows to a large size and are often bought by unsuspecting aquarists when small. They will rapidly outgrow smaller tanks, so the aquarium should be as large as possible.O. niger is especially light shy and should be provided with sheltered areas to hide. Although these fish are peaceful, very small tankmates are still at risk of being eaten.