Comparative Anatomy of Wild Adult African Catfish (Clarias garIepinus) Ovary During Rainy and Dry Periods in Zaria, Nigeria

Abstract

The study investigated effects of rainy and dry periods on the ovaries of wild adult Clarias gariepinus in Zaria, kaduna State Nigeria. Twenty-four wild adult catfish with average weight of 1000.00 ± 0.00 gm was used during both periods. They measured a standard body length of 50.17±1.01 cm (rainy) and 44.83 ± 2.09 cm (dry). The fish were sourced from Zaria dam and transported live to Gross Anatomy Laboratory in Ahmadu Bello University Zaria. Each fish was euthanized using tricaine anaesthetic at 8 drops/litre of water. The ovaries were extracted, weighed and fixed in Bouin’s fluid for 24 hours, and processed histologically. Grossly, the ovaries were observed to be well-developed and highly vascularized during rainy period while, regressed and poorly vascularized ovaries were seen during dry period. The mean weight of the ovaries (0.025) and Gonado-somatic index (GSI) value (0.034) were significantly higher during rainy period. Histologically, the ovaries were predominated by vitellogenic and post-vitellogenic follicles during rainy period while, previtellgenic follicles predominates dry periods. The tunica albuginea and interstitial connective tissues were thin during rainy period but thick during dry period. Hence, the result of this study revealed that wild adult catfish spawns during rainy period while, dry period is characterized by low gonadal activities in Zaria, Nigeria.