Komolafe O O, Arawomo G A O
Department of Zoology, Obafemi Awolowo University, Ile-Ife, Nigeria.
Rev Biol Trop. 2007 Jun;55(2):595-602. doi: 10.15517/rbt.v55i2.6034.
The fish family Cichlidae has a large diversity and dominates African freshwater bodies, with over 200 species reported in inland waters. Sampling for the fish Oreochromis niloticus (Linnaeus) in Opa reservoir, Nigeria, started in October 1997 and extended until February 2000. The fishing methods employed for collecting the 1 430 specimens were cast netting and gillnetting. Egg diameter varied between 2.12 mm and 2.69 mm with a mean of 2.47+/-0.02. Female gonadosomatic index was 1.34+/-0.01 (0.12-4.06, n= 637). The male gonadosomatic index was 0.39+/-0.02 (0.03-1.67, n=789). In Opa reservoir, O. niloticus bred throughout the study period. The species was a maternal mouth brooder with the female fish carrying eggs and fry in the buccal cavities. The sex ratio of O. niloticus was approximately 1:1 in the reservoir. The fecundity of the species was between 73 eggs and 1 810 eggs per female with a mean fecundity of 815 eggs.
丽鱼科鱼类种类繁多，在非洲淡水水域占主导地位，据报道在内陆水域有200多种。1997年10月开始在尼日利亚奥帕水库对尼罗罗非鱼（Linnaeus）进行采样，一直持续到2000年2月。采集1430个样本所采用的捕鱼方法是撒网和刺网。卵径在2.12毫米至2.69毫米之间，平均为2.47±0.02。雌鱼的性腺指数为1.34±0.01（0.12 - 4.06，n = 637）。雄鱼的性腺指数为0.39±0.02（0.03 - 1.67，n = 789）。在奥帕水库，尼罗罗非鱼在整个研究期间都有繁殖。该物种是母性口育鱼类，雌鱼在口腔中携带卵和鱼苗。水库中尼罗罗非鱼的性别比例约为1:1。该物种的繁殖力为每只雌鱼73至1810枚卵，平均繁殖力为815枚卵。
