Threadfin Acara

About

The threadfin acara (Acarichthys heckelii) is one of those cichlids that rewards patient, attentive keepers with genuinely fascinating behavior you won't see from most other fish. Native to a broad sweep of South American river systems including the Amazon mainstream and tributaries like the Negro, Xingu, Trombetas, and Tocantins, it's a mid-sized cichlid with the elongated, filamentous fin extensions that give it its common name. The body is fairly typical of the geophagine cichlids it's related to, earthy and laterally compressed, with a bold lateral spot and iridescent scaling that shifts depending on the light. In the aquarium it tends to be reasonably tolerant of similarly-sized, peaceful tankmates and won't bother anything too large to fit in its mouth, but don't let that fool you into thinking it's easygoing across the board. Adults can turn on members of their own species with surprising ferocity, and this intraspecific aggression is one of the more serious challenges of keeping a group. Larger tanks and larger groups seem to reduce the worst of this behavior. Breeding is where things get really interesting. Females naturally excavate complex tunnel systems in the substrate to deposit eggs, an arrangement nearly impossible to replicate fully at home, though spawning has been achieved with patience and improvised caves.