Identification: Body color varies from greenish to grey, with yellow and blue reflections, and can vary within individuals depending on condition, temperature, and social status. There are several dark-brown vertical bars and two blotches (one in the middle of the body and one on the caudal peduncle). Reproductive individuals may have a bright red border around their eyes with the soft rays on the dorsal and anal fins extended into filaments (Staeck and Linke 1995).
Cichlasoma dimerus has typically three anal spines, unlike the otherwise similar C. bimaculatum (Black Acara) which has typically four anal spines (Kullander 1983). The caudal fins of C. dimerus are characterized as having a web-like pattern of dark bands and caudal rays with the clear spaces between the rays and bands being larger in the upper caudal than the lower caudal fin; by contrast, the caudal fins of C. bimaculatum have pale bands and the appearance of a symmetrical dotted pattern (Robins et al. 2020). Scales of C. dimerus have thick gray to black margins on the posterior edge, especially on the head, nape, and anterior-upper flanks, while margins on C. bimaculatum scales were absent to light, and narrow (Robins et al. 2020).
† Populations may not be currently present.
Ecology: In the Cuiabá River basin, Brazil, C. dimerus were generalist consumers, with diets consisting primarily of plant matter, terrestrial insects, and aquatic insects, with detritus, scales, fish, and algae also present (Novakowski et al. 2016). Unlike other species in this study, microcrustacean zooplankton were entirely absent from C. dimerus diets; this is consistent with C. dimerus having relatively short and widely-spaced gill-rakers (Novakowski et al. 2016).
Although C. dimerus can tolerate temperatures ranging from 6°C to 30°C (Staeck and Linke 1995), optimal breeding temperature is around 25-27°C (Meijide and Guerrero 2000, Meijide et al. 2005). Mating season varies from September to April in lower latitudes to November to March in higher latitudes of their native range (Tubert et al. 2012). Forming pairs, C. dimerus defends territories in which they spawn; eggs are laid on cleaned substrate and fry are moved by mouth into pits (Pandolfi et al. 2009). Breeding females are especially aggressive towards conspecific intruders (Tubert et al. 2012). Substrate-brooders, C. dimerus may spawn every 15-20 days and lay up to 1500 eggs per spawning event (Alonso et al. 2011, Pandolfi et al. 2009). In optimal conditions, C. dimerus can reach about 50 mm by four months after hatching (Pandolfi et al. 2009).
Romero and Casatti (2012) show that C. dimerus prefers habitats with macrophytes and fine roots, while Bessa et al. (2017) found C. dimerus most abundant over hard substrates. These differences may reflect seasonal use, habitat availability, interspecific competition, or predator avoidance and support the generalist tendencies of this species. They are tolerant of low dissolved oxygen that may kill most other species (Staeck and Linke 1995) and have been observed dispersing through extremely shallow water at the beginning of the rainy season (Sucksdorff 1981, in Kullander 1983).
References: (click for full references)
Alonso, F., M. Canepa, R.G. Moreira, and M. Pandolfi. 2011. Social and reproductive physiology and behavior of the Neotropical cichlid fish Cichlasoma dimerus
under laboratory conditions. Neotropical Ichthyology 9(3):559-570.
Aquarium Stock Company. 1932. Special 20th anniversary price list: Tropical fishes and aquarium supplies.
Bessa, E., B. Geffroy, E. Goncalves-De-Freitas. 2017. Tourism impact on stream fish measured with an ecological and a behavioural indicator. Aquatic Conservation: Marine and Freshwater Ecosystems 27:1281-1289.
Courtenay, W.R., Jr., H.F. Sahlman, W.W. Miley II, and D.J. Herrema. 1974. Exotic fishes in fresh and brackish waters of Florida. Biological Conservation 6(4):292-302.
Kullander, S.O. 1983. A revision of the South American cichlid genus Cichlasoma (Teleostei: Cichlidae). Swedish Museum of Natural History, Stockholm, Sweden.
Meijide, F.J., and G.A. Guerrero. 2000. Embryonic and larval development of a substrate-brooding cichlid Cichlasoma dimerus (Heckel, 1840) under laboratory conditions. Journal of Zoology 252(4):481-493.
Meijide, F.J., F.L. Lo Nostro, and G.A. Guerrero. 2005. Gonadal development and sex differentiation in the cichlid fish Cichlasoma dimerus (Teleostei, Perciformes): A light- and electron-microscopic study. Journal of Morphology 264: 191-210
Novakowski, G.C., F.A.S. Cassemiro, and N.S. Hahn. 2016. Diet and ecomorphological relationships of four cichlid species from the Cuiabá River basin. Neotropical Ichthyology 14(3):e150151.
Pandolfi, M., M.M. Canepa, F.J. Meijide, F. Alonso, G. Rey Vazquez, M.C. Maggese, and P.G. Vissio. 2009. Studies on the reproductive and developmental biology of Cichlasoma dimerus (Percifomes, Cichlidae). Biocell 33(1):1-18.
Rivas, L.R. 1965. Florida freshwater fishes and conservation. Quarterly Journal of the Florida Academy of Sciences 28:255-258.
Robins, R.H., M.E. Brown, and R.A. Crutchfield. 2020. Identification of acara (Cichlidae: Cichlasoma) established in Florida, USA. BioInvasions Records 9(1): 133-145.
Romero, R.M. and L. Casatti. 2012. Identification of key microhabitats for fish assemblages in tropical Brazilian savanna streams. International Review of Hydrobiology 97(6):526-541.
Staeck, W. and H. Linke. 1995. American cichlids II: Large cichlids. A handbook for their ideintification, care, and breeding. 1st completely revised edition edition. Tetra-Verlag, Germany.
Tubert, C., F. Lo Nostro, V. Villafane, and M. Pandolfi. 2012. Aggressive behavior and reproductive physiology in females of the social cichlid fish Cichlasoma dimerus. Physiology & Behavior 106(2):193-200.
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.