Abstract
To examine the hypothesis that the histochemical characteristics of teleostean mucus reflect functional characteristics, mucous cells were studied in four related and behaviourally similar species of fish (Family Belontidae). Histochemical characteristics were determined with Alcian Blue at both pH 2.6 and pH 1.0 followed by the periodic acid-Schiff technique. It was found that the four species differed in glycoprotein type as well as in number of mucus-containing cells. The differences are ciscussed in regard to functional characteristics and environmental influence.