Red Threadfin Acara 4-5"

Threadfin Acara, Acarichthys heckelii, is a distinctive South American cichlid native to the Amazon Basin and surrounding river systems, with a natural range that includes Brazil, Peru, Colombia, Guyana, and portions of the Rio Essequibo drainage. It inhabits slow-moving rivers, flooded forests, lagoons, and quiet tributaries with extensive sandy substrates, submerged wood, roots, and leaf litter. These warm tropical habitats provide the soft substrate that plays an important role in the species’ natural feeding and breeding behavior.

Adult Threadfin Acaras typically reach about 7 to 8 inches in length, with mature males often becoming larger and developing more elaborate finnage. The body is elongated and moderately deep with a warm silver, gold, or olive base covered in beautiful pearlescent blue-green spotting. A prominent dark blotch appears along the middle of the flank, while additional dark markings and vertical shading may become more pronounced depending on mood. The feature that truly sets mature Threadfin Acaras apart is their spectacular finnage. The dorsal fin develops long trailing extensions, often accented with fiery orange-red coloration and brilliant metallic blue patterning, while the anal and caudal fins can develop similar iridescent blue, red, and orange highlights. Fully mature specimens are exceptionally colorful and become increasingly impressive with age.

A tank of at least 75 gallons is recommended for a single adult or compatible pair, with 100 gallons or larger preferred for groups or community setups. Fine sand is strongly recommended because Threadfin Acaras naturally sift and excavate the substrate. Driftwood, branches, rocks, and open sandy areas create an ideal environment, but structures should be positioned securely because these fish can move significant amounts of substrate. Plants can be incorporated, although delicate or poorly rooted species may be disturbed by digging.

Water conditions should remain warm, clean, and stable. Temperatures between 76 and 84 degrees Fahrenheit are appropriate, with a pH range of approximately 5.5 to 7.5 and soft to moderately hard water. Strong biological filtration and regular water changes are important, particularly as these fish mature and their bioload increases. Gentle to moderate water movement and good oxygenation are ideal.

Threadfin Acaras are omnivorous benthic feeders that naturally search through sand and detritus for insect larvae, worms, crustaceans, and other small organisms while also consuming some plant and organic material. In the aquarium they readily accept quality cichlid pellets, sinking foods, frozen bloodworms, mysis shrimp, brine shrimp, chopped shrimp, and other appropriately sized foods. A varied diet helps develop the intense coloration and elaborate finnage seen in mature specimens.

Temperament is generally peaceful to moderately territorial for a cichlid of this size. Threadfin Acaras can be successfully maintained with other medium to large, relatively peaceful South American fish, including larger tetras, silver dollars, Geophagus and other compatible eartheaters, peaceful catfish, and similarly tempered cichlids. Territorial behavior becomes considerably stronger during breeding, and adequate floor space and visual barriers are important when maintaining multiple cichlids.

Breeding behavior is particularly fascinating. Acarichthys heckelii is a substrate-spawning cichlid that naturally excavates tunnels or burrows in sandy banks for reproduction. In aquariums, pairs may dig beneath wood, rocks, or other structures and create surprisingly elaborate spawning chambers. Both parents participate in defending the breeding territory and caring for the developing young, and their normally moderate temperament can become significantly more assertive while guarding offspring.

Acarichthys heckelii is an exceptional centerpiece cichlid that becomes dramatically more beautiful as it matures. Its shimmering blue-green spotting, fiery fin coloration, long thread-like dorsal extensions, sand-sifting behavior, and unusual burrow-spawning strategy make the Threadfin Acara one of the most distinctive South American cichlids available to aquarists.