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Morphological differences between females and males spined loaches belonging to five species from the Adriatic basin were examined. Besides the presence of the Canestrini scale and the length of the pectoral fins, sexual dimorphism is also visible in the position of the pectoral fins, as well as in the length of the pelvic fins. Both pectoral and pelvic fins are significantly longer in males than in females, whereas pectoral fins of females are located more anteriorly then in males. Differences in the length of pectoral and pelvic fins among species are also revealed. The role of the observed secondary sexual characters in males is probably connected with their special mating behavior. Furthermore, a hypothesis that habitat conditions have greater impact on body dimensions of females than males is proposed.

Croatian Adriatic river system consists of six rivers with their tributaries: Mirna, Rasa, Zrmanja, Krka, Cetina and Neretva. The presence of genus Cobitis has been recorded in only three of them: Zrmanja, Cetina and Neretva. There are some specimens of genus Cobitis from the river Zrmanja. This area was never studied systematically and therefore there are not enough records to analyse Zrmanja's fish fauna. In the river Cetina genus Cobitis is a rare genus. It lives in a community of five species and represents just a 2.9 percent in total number of fish individuals and 0.14 percent in total biomass (20 years old data). In river Neretva genus Cobitis is a common genus with just a 3.6 percent in total number of fish specimens and 0.38 percent in total biomass. If we compare percentage number of fish individuals for genus Cobitis in Neretva and Cetina, at first sight we would not see a great difference, but the fish community in river Neretva consists of 33 different fish species and genus Cobitis is a very important genus there. In this paper we compare present records of the fish community in the River Cetina with the old one. We also compare fish communities of Neretva and Cetina and analyse status of genus Cobitis in each of them.