Feeding ecology of Oreochromis niloticus (Linnaeus) & Tilapia Zillii (Gervias) in a Nile canal
- 1) Zoology Department, Faculty of Science, Almenofeya University, Shebeen Alkoom, Egypt
Fish stomachs, 1149 for Tilapia zillii and 1698 for Oreochromis niloticus, were collected from April 1984 till April 1985 from a Nile canal in the Egyptian delta. Both species showed a significant overlap of diet (Schoener's index) among individuals ranging from 12 to 17.9 cm standard length. Outside this range differences in the importance of food of animal origin occurred. Macrophytes were the main food of O. niloticus and aquatic insects of the food of T. zillii. This initial diet overlap may have contributed to irregularity in the increase of full stomachs with increasing length, and to a decline of the stomach index (SI = stomach weight × 100/fish weight) with increase in length in O. niloticus. The stomach of either species correlated significantly with water temperature, but with daily photoperiod in O. niloticus only.
- 1 - sciences appliquees, technologies et medecines
- 2 - sciences biologiques et medicales
- 3 - sciences biologiques fondamentales et appliquees. psychologie
- 4 - psychologie. psychophysiologie