The Fecundity of Tilapia Species

Abstract

Fecundity has been defined as the number of young produced by an individual during its lifetime. Factors influencing fecundity are: length of breeding season, frequency of spawning during a breeding season, the number of eggs laid at a spawning. and the care taken of eggs before and after hatching. 2. According to whether they care for their young outside or inside the mouth, Tilapia can be classified as "guarders" or "brooders". Generally, guarders produce many small eggs and brooders fewer, large ones. 3. Only four species are known to be guarders: T. sparrmani. T. guillasalla. T. melanopleura and T. zillii. The remainder are brooders. 4. Due to the different breeding biology of the two groups, the fecundity of guarders depends upon the number of paired fishes, whereas in brooders it is determined by the number of ripe females. 5. In the genus Tilapia. evolution appears to have been towards a reduction in the number of eggs produced, and towards the development of a brooding habit.