Polychromatism in Cichla: color patterns and potential drivers

Neotropical cichlids are characterized by spectacular color diversity, but some groups remain poorly investigated. In this context, the present study characterized color traits in peacock basses ( Cichla kelberi and C. piquiti ) from the Middle Tocantins River (Brazil), and investigated the link with biological (development, sex, reproduction) and environmental drivers (feeding and water transparency). Both species showed striking polychromatism, but with some conspicuous patterns. For C. kelberi , immature and non-reproductive individuals were associated with melanistic patterns and the absence of spots, with either conspicuous or opaque vertical bars. Adults in reproduction, on the other hand, were associated with yellow body, spots in the fins, and dorsal blotches. For C. piquiti , immature and non-reproductive individuals showed a wide range of color patterns, but associated with non-blue tints. Immature fish, in particular, had spots in the body and head, and a red caudal fin. Reproductive fish were associated with blue hues, the absence of spots and a non-red caudal lobe. For both species, color variation was not associated with feeding, sex and water transparency. Our findings indicate that coloration represents transient (but stable) phenotypic states subjected to unidirectional or cyclical changes, supporting the hypothesis that growth and reproduction drive color variation in Cichla .