Premium
The growth of Tilapia mossambica Peters (Pisces: Cichlidae) in Lake Sibaya, South Africa
Author(s) -
Bruton M. N.,
Allanson B. R.
Publication year - 1974
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1974.tb05113.x
Subject(s) - biology , tilapia , fish <actinopterygii> , population , ecology , fishery , zoology , demography , sociology
The scales of Tilapia mossambica Peters * from Lake Sibaya show clear rings formed by broken, widely‐spaced circuli in the anterior field. In order to determine the rate and time of scale ring formation, the number of circuli in the marginal increment was determined. Five scales from the pectoral region of 2223 fishes caught at regular intervals over two years were examined. When plotted as histograms, the number of circuli in the marginal increment showed a sharp movement to the left in September–October and again in January, indicating that the rings were formed during these months in the majority of fish examined. Pre‐ and postbreeding feeding migrations, and increases in condition factor, were associated with scale ring formation. Otoliths and opercula were also examined for age determination. Annual length increments were calculated for 450 T. mossambica collected throughout the year, and growth curves plotted. T. mossambica from Sibaya reach maturity after one year at a standard length of about 8 cm in females, and after two years at 10 cm in males. The breeding population had a standard length mode of 11–12 cm in females and 17 cm in males. The maximum final size was about 24 cm.