Diet composition and feeding habits of the African sharptooth catfish Clarias gariepinus (Burchell, 1822) from Ribb Reservoir, South Gondar, Ethiopia

Figures & data

Figure 1. The study area map reveals the sites of specimen collection of the Ribb Reservoir, Ethiopia.

Figure 2. The percentage contribution of geometric index importance (%GIIi) in the diet of C. gariepinus (n = 379) from Ribb Reservoir.

PKT—Phytoplankton; ZPK—Zooplankton; DET—detritus; SAG-sand grain; and OST-ostracod. Dotted vertical lines separate the different grades of favorite food items.

Table 1. Proportions of different food items in the diet of C. gariepinus (n = 379) in Ribb Reservoir, Ethiopia

Food items	%Oi	%Vi	%IP	%GIIi
Zooplankton	100	21.8	32.95	46.0
Cladocera	55.7	3.8	3.2	22.7
Copepod	73.1	17	18.8	34.4
Rotifer	10	0.6	0.1	4.0
Fish prey	36.1	48.8	26.6	32.0
Phytoplankton	55.7	5.9	4.96	23.3
Blue-green algae	45.6	5.4	3.7	19.5
Green algae	5.6	0.3	0.025	2.3
Euglenoids	4.5	0.2	0.01	1.8
Detritus	35.6	17.1	9.2	19.9
Insect	17.1	1.5	0.4	7.0
Ostracods	7.1	0.2	0.02	2.8
Sand particles	6	0.2	0.018	2.3
Macrophytes	3.7	0.4	0.01	1.5

Note: percentage frequency of occurrence (%Qi), percentage of volumetric contribution (%Vi), percentage index of preponderance (%IP) and percentage Geometric Index of Importance (%GIIi).

Figure 3. The size class variation in the diet of C. gariepinus in Ribb Reservoir, Ethiopia.

Figure 4. The relative importance of prey items (PIi% and GIIi%) with respect to size classes in the diet of C. gariepinus.

Table 2. Relative contribution percentage frequency of occurrence (%Qi), volumetric contribution (%Vi), index of preponderance (%PIi) and geometric index of importance (%GIIi) of different food items in the diet of Clarias gariepinus in Ribb Reservoir during the dry and wet seasons

Food items	%Oi		%Vi		%PIi		%GIIi
	Dry	Wet	Dry	Wet	Dry	Wet	Dry	Wet
Fish prey	66.1	5.4	63.6	3.7	64.5	0.11	40.5	3.8
Zooplankton	99.5	100	4.8	71.8	7.3	40.3	32.6	71.6
Cladocera	36.5	62.9	1.6	10.5	0.89	3.7	11.9	30.3
Copepod	48.4	94.1	2.4	61.1	1.8	32.3	15.9	64.7
Rotifer	14.6	3.2	0.8	0.2	0.2	0.003	4.8	1.4
Phytoplankton	64.6	96.8	1.2	22.2	1.2	12.1	20.6	49.6
Blue-green algae	49.5	92.5	0.7	21.8	0.5	11.3	15.7	47.6
Green algae	10.4	-	0.4	-	0.1	-	3.4	-
Euglenoids	4.5	3.8	0.2	0.4	0.02	0.01	1.5	1.8
Mud	20.8	1.6	7.4	0.4	2.4	0.003	8.8	0.8
Insect	25.0	7.6	0.2	1.8	0.1	0.08	7.9	3.9
Ostracods	13.5	-	0.2	-	0.04	-	4.3	-
Sand particles	11.5	-	0.2	-	0.04	-	3.7	-
Macrophytes	7.3	-	0.5	-	0.01	-	2.4	-
Plant seeds	1.6	-	0.03	-	0.001	-	0.5	-