By means column (CC), thin-layer (TLC) and high-performance liquid chromatography (HPLC) the authors investigated the effect of ecto- and endoparasites on the carotenoid content in fish in natural infection. The study was conducted using the following pairs of the host-parasite: with ectoparasites-Gasterosteus aculeatus and Argulus foliaceus; Tinca tinca and Ergasilus sieboldi and Mollienisia latipinna and Ichthyophthirius multifiliis; with endoparasites- Carassius auratus gibelio and Ligula intestinalis, Gasterosteus aculeatus and Schistocephalus solidus. In the material examined 23 carotenoids were identified, including four carotenoids relatively rare in fish: α-cryptoxanthin, mutatoxanthin, idoxanthin and cynthiaxanthin. In all the examined pairs of host-parasite, the parasitic organism always had higher total carotenoid content, compared to the host, and  in all cases the infected fish specimens (also in particular part of the body of tench) contained smaller amounts of carotenoids than healthy specimens. The data obtained indicate that some carotenoids are selectively accumulated by the respective parasites.