Study of fish fauna of the rivers Topolnitsa, Luda Yana, Stryama, Chepinska and Vucha all tributaries of the Maritza River was carried out. The research was conducted in the autumn of 2006 and 2007. The material was collected by electrofishing using unpuled direct current (DC). In the studied rivers the 11 sampling areas were marked and explored. During the investigation in these rivers 17 fish
... [Show full abstract] species belonging to 5 families were found. The family Cyprinidae was the most representative in the sample. The fish fauna composition was predominated by two reofilic species – Barbus cyclolepis and Squаlius orpheus. Among the species found in this study there was three alien fishes for the local fish fauna composition were found – Oncorhycus mykiss, Lepomis gibbosus and Pseudorazbora parva. The present study identified four species endemic to Aegean watershed – Gobio bulgaricus, Chondrostoma vardarense, Squalius orpheus and Vimba mela-nops. The author was found also two species endemic to Balkan Peninsula – Cobitis strumicae and Sabanejewia balcanica and one species endemic to Maritza River basin – B. cyclolepis. The estimated composition of the fish fauna in this study was composed of species characteristic mainly for the middle zone of the rivers. The present study showed some changes in the species composition of fish fauna have occurred in recent years. The species like G. bulgaricus which were prevalent before today are found in much smaller quantities. At the same time in the fish fauna composition the number of the species such as Lepomis gibbosus, Pseudorazbora parva, Carassius gibelio and Perca fluviatilis have increased. The author found some rarer species like Rhodeus amarus while the species that was common before as Carassius carassius was not established.
