Journal Of Tropical Biosciences
Volume No: 11|
Page No: 18
| FullText PDF
Title: A STUDY ON SOME ASPECTS OF BIOLOGY OF OREOCHROMIS NILOTICUS (LINNAEUS, 1758)
YASHIM, E.Y. AND SALAUDEEN, H.A
DEPARTMENT OF BIOLOGICAL SCIENCES, AHMADU BELLO UNIVERSITY, ZARIA.
This research provides information on the biological study of Oreochromis niloticus (Linnaeus, 1758) in Kubanni reservoir, Ahmadu Bello University, Zaria. The aspects of biology considered include morphometric analysis, food and feeding habits and age determination. Thirty (30) O. niloticus were randomly sampled; with 6 being females and 24 being males. This research was conducted for 2 months, the samples were kept in a lid tight container containing ice block before taking to the laboratory for the required examination. With respect to the morphometry, the specimens were tagged and measured with the aid of a measuring board and their respective weights taken using a sensitive weighing balance (Sartorius-CP8021). The food and feeding habits of the individual fish sample was determined by emptying the gut content into a petri dish and viewed under the microscope to identify the different food items contained in the diet of O. niloticus. The age of each sample was estimated using the scales around the area between the lateral line and pectoral fin, and growth marks on scales were used for determining the different ages of the fish samples. With respect to the morphometric, the highest of weight accrued was 425g, with a corresponding total length of 27.1cm. Also, the lowest of weight recorded was 36g, with a corresponding total length of 12.4cm. It was found that Algae amounted to be the food item with the highest level of occurrence, though vegetative matter, silt, and insect parts were part of the diet. Out of the 30 samples examined, 11 were found to be 1year (and above), 16 were found to be 2years (and above), and 3 were found to be 3years (and above). From the outcome of this research, it can be inferred that sub-adults are the predominant catch of O. niloticus in the sampled population, an indication that the reservoir has not been significantly overfished.
From the accrued results, it can be deduced that there is significant difference in the morphometrics of O. niloticus in Kubanni reservoir. Fish samples having their weights to be between 80-200g, form the bulk of the fish sample. This implies that sub-adults are the predominant catch in the fish sample. There is significant difference in the percentage occurrence of different food items with algae (95%) having the highest value. From this study, it can also be concluded that O. niloticus in Kubanni reservoir are of different ages; 1(and above), 2 (and above) and 3 (and above)