Studies on the biology of genus Synodontis at Khartoum

Abstract

1. The study of genus Synodontis at Khartoum showed that the vertebrae are the most reliable part of the skeleton for the determination of age. The otolith, opercular bones, and dorsal spine proved to be unreliable. 2. A remarkable correlation between age determined by the vertebral method and length is recorded. 3. Females of Synodontis spp. on the average are longer than the males of equal ages. 4. The growth of Synodontis is not uniform throughout life but it is fast during the first and third years and slow during the second and fourth years where it remains about the same in the succeeding years. However, the increments in length and weight do not show exactly the same pattern during the life of the fish. The fish seems to add more weight rather to increase in length in older stages. Increment in weight takes place during the first three years and fifth year while a drop in weight is observed during the fourth and sixth years onwards. 5. Different species of Synodontis show slightly different growth rates.