In this study, we have investigated the effects of Porphyridium cruentum (Rodophyta) as a natural pigment source and astaxanthin and beta-carotene as synthetic pigment sources on the skin colour of cichlid fish (Cichlasoma severum sp., Heckel 1840), which are generally light orange with white patches and becomes shiny orange in the reproductive phase. The fish were fed diets containing 50 mg kg(-1) astaxanthin and beta-carotene, and P. cruentum powder. The amount of both natural and synthetic pigment sources given as feed was 50 mg kg(-1), and the experiment was continued for 50 days. Total carotenoid content of the fish was determined spectrophotometrically at the end of the experiment. As a result, while a visible change of colour in the skin of the fish fed on the feed containing astaxanthin was observed with 0.34 +/- 0.2 mg g(-1) of pigment accumulation, a relatively small change of colour was observed in the skin of other fish that were fed on the feed containing P. cruentum and beta-carotene with 0.22 +/- 0.2 mg g(-1) and 0.26 +/- 0.1 mg g(-1) of pigment accumulations, respectively. Therefore, it was determined that these pigment sources have an effect on the colour of cichlid fish.