后臀丽鱼

Overview

A warm-water current specialist, Retroculus lapidifer needs a large river-style aquarium with ample oxygen and very clean water. Substrate sifting and the construction of pebble-covered nests are characteristic behaviors.

Distribution & habitat

Most records come from the Tocantins and Araguaia systems of Brazil, with additional occurrences in the Capim and Gurupi drainages. Clear-water rapids and fast river stretches contain boulders of varied sizes, with quieter sandy or gravelly pools at the margins.

Aquarium setup

Provide at least a 210 by 60 cm footprint and maintain 26–32 °C. Use soft sand with small pebbles, plus boulders, roots, and branches. Hardy attached plants are possible. Strong water movement and high dissolved oxygen are important, with effective filtration and weekly changes of about 30–70%. Recently imported wild fish can be delicate and susceptible to white spot, warranting careful quarantine.

Diet & feeding

Benthic aquatic invertebrates dominate the wild diet, especially insect larvae. Food suspended in the current and small fishes may also be taken. Offer fine prepared foods, varied live or frozen aquatic items, and suitable gel foods; include some plant-containing dry food. Three to five small daily meals support condition better than one large feeding.

Behaviour & compatibility

Outside breeding, it is relatively peaceful but may consume smaller companions. Calm fishes using open water are preferable to other bottom-oriented species except in very large tanks. Keep five to eight individuals so the natural loose grouping can develop. Smaller groups may leave weaker fish exposed to disproportionate aggression.

Sexual dimorphism

Adult males are slimmer, especially along the nearly straight belly between the pelvic and anal fins; females are rounder there. Enlarged male pelvic fins can support display postures. Juveniles lack useful external differences. Breeding fish intensify dark pigmentation beneath the head and body and on the pelvic fins.

Breeding

This biparental substrate spawner has reproduced in aquaria. Natural pairing requires patience: maturity can take one year and often two or more. Good feeding and rigorous maintenance support spawning. The pair excavates pits and deposits roughly 200 or more adhesive eggs, which collect sand and are then covered with pebbles or debris. The nest is moved during incubation. Hatching begins after three to four days, with larvae remaining near the nest rather than buried. Offer small live foods after yolk absorption. Some parents guide fry back to the nest before nightfall and disturb substrate, possibly exposing food for them.

Notes

The absence of conspicuous dark tail bars helps separate it from some relatives. Its resemblance to earth-eating cichlids does not indicate membership in the same group.