黄臀珠母丽鱼 · Threadfin Acara

Overview

Acarichthys heckelii reaches about 20 cm and continually rearranges the bottom. Although often relatively tolerant of suitable tankmates, adults can suddenly attack conspecifics severely enough to kill weaker fish. Generous space and consistently clean water are both central to long-term care.

Distribution & habitat

Its native range covers the northern Amazon basin in Colombia, Peru and Brazil, together with Guyana's Essequibo drainage. It occupies lowland river environments and enters flooded forest or savanna during the wet season. The Singapore population is introduced rather than native.

Aquarium setup

A footprint of 150 × 45 cm is only just acceptable for a pair; a group needs substantially more room. Sand, subdued lighting and branching wood make a useful arrangement. Persistent digging means that gravel-based layouts are also likely to be rearranged.

Use an established aquarium with ample canister or sump filtration, while arranging outlets to avoid strong current. Replace at least roughly 50–70% of the water weekly. Mechanical filtration should intercept suspended particles without allowing sand to pass continually through equipment, where it can cause wear or blockages. Poor maintenance or nutrition can accompany impaired growth and erosion around the head and lateral line.

Diet & feeding

Unlike some related cichlids, this fish does not feed by sifting sand and spends substantial time in midwater. Offer a varied rotation of live, frozen and dried foods, including vegetable material such as blanched spinach or a spirulina-containing preparation.

Behaviour & compatibility

Peaceful companions with matching requirements and bodies larger than a few centimeters may work; very small fish remain vulnerable. Avoid strongly territorial or aggressive species and fin nippers. Keeping it with freshwater stingrays has produced both successes and losses to nighttime predation, so that combination is not reliably safe.

Sudden aggression within the species requires particular attention. Larger aquariums and groups appear to reduce problems, but do not remove the need to watch subordinate fish and developing pairs.

Sexual dimorphism

Sexually mature females are generally thicker-bodied than males.

Breeding

Maturity takes approximately two to three years. Wild females compete for sites and excavate burrows with entrances, tunnels and an enlarged egg chamber before attracting a male. The female performs most brood care while the male defends the area. Threatened fry retreat into the burrow; parental care usually ends near 10 mm in length.

An aquarium cannot readily reproduce that entire structure. A large inverted flowerpot with an entrance cut into its base has worked as a substitute. Even a single pair needs ample space, close observation and preferably little competition. Temperature variation and substantial water changes simulating weather shifts have encouraged courtship, but severe aggression between partners remains the principal obstacle. Once spawning succeeds, fry are reportedly relatively straightforward to raise.

Notes

This is the sole member of its genus. Neither its trailing fins nor its midwater activity should obscure its digging behavior, and tolerance of other species should not be assumed to apply to adult conspecifics.