T. HUBENOVA, A. ZAIKOV and J. KARANIKOLOV
Institute of Fishery and Aquaculture, BG-9000 Varna, Bulgaria
HUBENOVA, T., A. ZAIKOV and J. KARANIKOLOV, 2002. Investigation on exterior and gonad development in one summer old pike (Esox lucius L.). Bulg. J. Agric. Sci., 8: 97–102
The exterior and gonad development in one summer old pike, raised in pond along with one summer old carp (Cyprinus carpio L.) have been examined. It is determined that during the first summer it reaches an average body weight of 75.48 g and length 19.52 cm. The specimens which weight is from 50 g to 100 g (65 %) prevail. Significant differences in the exterior between the female and male fish are determined according to 5 features. The weight and the length of the body of the female pike are bigger, and the length of the caudal peduncle, the postdorsal distance and the length of the pectoral fins – of the male ones. As a tendency the length of all fins in the male specimens is bigger. The male pike reach maturuty in the first year of breeding (February). Stage III-IV of gonad development of the female specimens is determined in the autumn-winter period, which is characterized by an actively running vitellogenesis in the D-oocytes.