Table 5. Diet compositions of Oreochromis niloticus in Lake Hawassa on a rainy (n = 711) and dry (n = 248) months

Food items	Frequency of occurrences (%)		Volumetric contribution (%)		Index of preponderance (%)
Food items	Rainy	Dry	Rainy	Dry	Rainy	Dry
Phytoplankton’s	96.20^a	94.35^a	87.70a	89.55^a	96.36^*	96.86^*
Diatom	77.07	85.89	20.31	22.84	17.88	22.48
Green algae	63.43	67.34	19.26	15.43	13.96	11.91
Blue-green algae	84.25	79.44	43.44	48.19	41.79	43.89
Dinoflagellates	25.60^**	13.71^**	2.72^**	1.17^**	0.80^**	0.18^**
Euglenoids	16.88^**	20.56^**	1.95^**	1.92^**	0.38^**	0.45^**
Zooplanktons	15.05^a	18.15^a	1.65^a	1.77^a	0.28^*	0.37^*
Cladocera	6.19	9.68	0.48	0.61	0.03	0.07
Rotifers	6.47	6.45	0.64	0.99	0.05	0.04
Copepods	4.36	4.44	0.54	0.34	0.03	0.02
Detritus	32.07^a	28.23^a	8.25^b	4.18^a	3.02^*	1.35^*
Macrophyte	15.33^a	29.44^b	1.91^a	4.20^a	0.33^*	1.42^*
Nematode	0.84^a	ND	0.06^a	ND	0.00^*	0.00^*
Fish egg	0.42^a	0.40a	0.32^a	0.30^a	0.00^*	0.00^*
Digested muscle	0.42^a	ND	0.11^a	ND	0.00^*	0.00^*

Values of respective food items under the same category given different superscript letters are significantly different (α < 0.05).
Values of respective food items under the same category given different superscript letters are significantly different between rainy and dry months comparisons.-
ND, not detected.