The Biology of the African Bonytongue Heterotis niloticus (Cuvier, 1829) from the Lower Niger River at Agenebode in Edo State, Nigeria

Table 3

Percentage composition of various food items consumed by Heterotis niloticus.

Food items	%NO	%FO	%W	IRI	%IRI
Copepods	35.42	33.48	43.71	0.34	34.45
Shrimps	18.75	16.74	14.22	0.18	17.74
Mollusc	7.64	14.16	16.85	0.11	10.90
Plant parts	8.33	12.02	6.74	0.10	10.18
Sand	5.56	3.43	2.69	0.04	4.49
Fish	7.64	5.58	10.01	0.07	6.61
Detritus	16.67	14.59	5.79	0.16	15.63
Total	100	100.00	100.00	1.00	100

NO: numerical method, FO: frequency of occurrence method, : gravimetric method, IRI: index of relative importance. Food items with %IRI >3 are regarded as primary and >0.1 to <3 are secondary, whereas those with %IRI <0.1 are considered as incidental food items.