PECULIARITIES OF REPRODUCTIVE BIOLOGY OF LAZY GUDGEON (SARCOCHEILICHTHYS SINENSIS) AND CHERSKY'S GUDGEON (SARCOCHEILICHTHYS CZERSKII) (CYPRINIDAE, GOBIONINAE)

Biological characteristics of mature specimens of Chersky's gudgeon (Sarcocheilichthys sinensis Beeker 1871) and lazy gudgeon (S. czerskii Berg 1914) are presented. The ovipositors in both species were found to have a similar structure. The ovipositor wall is covered by a multi-layered squamous epithelium. The basement membrane separates external epithelium from middle connective tissue. The internal layer of the ovipositor is formed by epithelium of the transitive type. The development of the ovipositor may be divided into several stages: the length of ovipositor gradually increases and reaches the maximum length (the time of egg deposition); after spawning it decreases and then returns to its initial size. The development of gudgeon eggs is asynchronous. Oocytes of different generations are present in the ovary at the same time that is characteristic of fractional spawning.