Pacu fish (lat. Colossoma macropomum) is a freshwater ray-finned fishes kind from the subfamily Serrasalminae, Characidae family, or (according to another classification) from Serrasalmidae family, the only kind of Colossoma genus. It is one of the piranha families known for its blood lust. But unlike its “cousins” and despite a strong and massive body, this fish prefers plant food and belongs to the herbivorous class.
The giant gourami (lat. Osphronemus goramy) is the largest fish from all gourami species kept in tanks. In the wild, it can grow up to 60 cm (24 in) long and even larger, according to some data. In tanks, it grows a bit smaller, about 40-45 cm (18 in), but still, it is a very large fish.
Fire eel (Mastacembelus erythrotaenia) resembles a true eel, that’s why the fish got its name. However, this fish has nothing in common with eels despite its snake like body and pointed snout. This is a renown tank and commercial fish.
Motoro stingray or ocellate river stingray (Lat. Potamotrygon motoro) is one of the most famous and popular freshwater rays. We should mention that despite the motoro stingray popularity in aquarium husbandry, there is still no quite precise classification of this family representatives.
From time to time, some new kinds are discovered, which were not described before.