fish · Cichlidae
Threadfin acara
Acarichthys heckelii
Wild range: Main course of the Amazon in Peru, Colombia and Brazil, including the lower Putumayo, Trombetas, Negro and Xingu rivers, the lower Tocantins and Capim, and the Branco; also the Essequibo River in Guyana (FishBase; Catalog of Fishes). (South America)
At a glance: Threadfin acara care
Compiled reference information. Review the care notes and original sources below.
What temperature is listed for Threadfin acara?
The compiled profile lists 23.0–28.0 °C for Threadfin acara (Acarichthys heckelii). Check the original sources below for context and differing recommendations.
What tank size is listed for Threadfin acara?
The profile lists a minimum tank volume of 79.0 US gallons (300.0 liters). Volume alone does not establish suitability; consider dimensions, group size and other inhabitants alongside the full care notes.
What pH is listed for Threadfin acara?
The compiled profile lists a pH of 6.0–7.0. Review the cited care sources alongside the other water parameters in this profile.
Natural habitat
A medium-sized South American cichlid named for the long red-tipped threads trailing from the back of its dorsal fin. Adults reach about 20 cm and show rows of shining blue-white spots on a yellowish to silvery body. It is generally calm and spends much of its time in midwater, but it digs constantly and some adults turn suddenly aggressive towards their own kind. It needs a large, mature tank with soft sand and very stable, clean water.
Where they are found
Acarichthys heckelii (Müller & Troschel, 1849) is valid in ITIS (TSN 648230; ITIS gives the authorship as Müller and Troschel in Schomburgk, 1849), GBIF (2371393, accepted), FishBase and Eschmeyer's Catalog of Fishes. It was described as Acara heckelii, and Geophagus thayeri Steindachner, 1875 and Acara subocularis Cope, 1878 are synonyms (Catalog of Fishes; FishBase; Seriously Fish). The name is also often spelled Acarichthys heckeli in the hobby. It is the only species in the genus Acarichthys; the older ITIS name Acarichthys geayi is now Guianacara geayi. Redescribed from Peruvian material by Kullander (1986) (FishBase). Native to the Amazon and Essequibo basins in Brazil, Colombia, Guyana and Peru; introduced to Singapore (Catalog of Fishes; Seriously Fish). Max size 19.5 cm SL and 20 cm TL (FishBase). The species name honours the Austrian ichthyologist Johann Jakob Heckel. IUCN: Least Concern (assessed 28 October 2020, via FishBase).
Aquarium care
A pair needs a tank with a base of at least 150 x 45 cm, about 300 L, and a group needs considerably more (Seriously Fish; AquaInfo recommends 180 cm long). Keep it at about 23-28°C, pH 6.0-7.0 and soft to moderately hard water (5-12 GH). Hosts differ: FishBase and AquaInfo give 23-26°C, Fishipedia 23-28°C and Seriously Fish 24-30°C; for pH, AquaInfo gives 6.5-7.0, Fishipedia 5.5-7 and Seriously Fish 6.0-8.0. Use a soft sand substrate because it digs all the time. Add driftwood, roots and a few caves, keep the lighting fairly dim, and use only hardy plants anchored in pots. It is sensitive to poor or unstable water, so add it only to a mature tank, filter strongly without creating a strong current, and change a large share of the water every week (Seriously Fish; AquaInfo).
Feeding
An omnivore that takes most foods but needs variety to keep its best condition and colour. Offer sinking pellets alongside frozen and live foods such as shrimp, mussel, krill and earthworms, plus some vegetable matter such as blanched spinach or a Spirulina food (Seriously Fish; AquaInfo). Some wild-caught fish are slow to take dried food at first (AquaInfo).
Compatibility
Generally peaceful towards other species and will only eat fish of a couple of centimetres or less (Seriously Fish). It is calmer kept in a group in a big tank. Some adults show sudden, extreme aggression towards their own kind that can kill weaker fish, and this happens less in larger groups and tanks (Seriously Fish; Aquarium Glaser). Good tankmates are similar-sized, peaceful South American fish such as larger tetras, eartheaters, severums and catfish. Avoid very aggressive cichlids and fin-nippers. Freshwater stingrays have sometimes eaten them at night (Seriously Fish).
Breeding
Breeding in the aquarium is uncommon. It is a cave spawner, not a mouthbrooder. Fish need 2-3 years to mature. Offer a large upturned flowerpot with an entrance hole or a covered jar, and use warm water (about 27-30°C) and large water changes to trigger spawning (Seriously Fish; AquaInfo; Aquarium Glaser). The female guards the eggs in the cave while the male guards the entrance. The eggs hatch in about 3 days and the fry swim free after about another 6 days. Raise them on newly hatched brine shrimp (AquaInfo). Watch pairs closely, because one partner may kill the other (Seriously Fish).
Sources
Compiled from multiple independent care sheets — not copied from a single site.