L. marmoratus can reach a little more than 100 centimetres (39 in) TL and has a maximum published weight of about 12 kilograms (26 lb).[2]L. pictus grows to 60 cm (24 in) TL.[3]
These two species can be easily confused. The body of L. pictus is brown with darker brown spots, with a paler ventral coloring. In juvenile L. pictus, two parallel, pale bands curve from the dorsal fin down the body towards the caudal fin.[4] In young fish of both species, the maxillary barbels are very long and ringed with black and white.[5] As both of these species grow, their barbels will shorten in proportion to their size, and the caudal fin lobes, which are rounded in the young, become much more pointed.[4][5] As L. marmoratus grows older, it darkens and its dark spots develop into a marbled pattern.[5] Both species have a large, sail-like dorsal fin.[4][5]
L. marmoratus is found in the Amazon, Essequibo, and Orinoco River basins.[2] On the other hand, L. pictus is only found in the Amazon and Orinoco River basins.[3]
Ecology
L. marmoratus inhabits riverbeds, deep wells, and lakes. Young or sub-adults form large schools. This species prefers to lay over rock and tree trunks during the day, being more active at sunrise, sunset, and night.[2]
Importance to humans
In aquaria
Both L. marmoratus and L. pictus are ornamental fish kept as pets in the aquariumhobby.[6] They have a voracious appetite and can grow rapidly, and therefore should be kept in a very large aquarium. These fish are peaceful towards other large fish.[5] Some sort of retreat to allow these fish to hide during the day is required.[4][5] These fish get very large and are not recommended for the average aquarist.[4]
