Vol. 1, Issue 7 (2016)
Impact of stomach state of fish on the intensity and abundance of parasites
Author(s): Okoye Ikem C, Abu Simon J, Obiezue Ndunwanne NR, Agbu Raymond A, Okoh, Felicia N, Okoro, Joseph O
Abstract: The food and feeding habits and their possible effects on gastrointestinal parasite intensity and abundance of the fish of a natural lake in Southeast Nigeria was investigated as part of the measures to enhance the yield and management of inland water resources. The guts of freshly caught fish were dissected in clean dissecting trays and the contents washed into Petri dish using 4% formaldehyde for examination of food contents and helminth parasites under a dissecting microscope. The degree of fullness of each stomach was estimated by an arbitrary 0 –16 points scale thus 0, 8 and 16 points were allotted to empty stomach (ES), partially filled stomach (PS) and full stomach (FS) and then used to evaluate patterns in feeding activities. The percentage of full stomach varied from 0% in C. guntheri and P. obscura to 57.0 % in T. zillii. T. zillii had the highest percentage (52.7%) of partially filled stomach while P. obscura had the least (0%). The highest percentage (31.2%) for empty stomach was also found in T. zillii and the least (0.4 %) in A. occidentalis. The food items isolated were mud, sand, debris, plant parts, insect larvae, copepods and fish fries. The most frequently encountered food item was mud (78.4%) while the least was debris (0.3%). In Neoechinorhynchus sp.1, hosts with full stomachs had significantly higher prevalence and carried heavier parasite burden (5.2 ± 6.57) (F = 8.628, d.f. = 2, p =0.000) than those with either partially filled stomachs (3.4 ± 2.80) and or empty stomachs (2.8 ± 1.97). Mean abundance was also significantly higher in fishes with full stomach than in others for Neoechinorhynchus sp.1 (F = 16.359, d.f. =, p =0.000) and Neoechinorhynchus sp. 2 (F = 9.600, d.f. =3, p= 0.000), but in terms of Neoechinorhynchus sp. 2, abundance was higher among those with empty stomachs (12.73 ± 30.58) than those with either partially filled stomachs (5.27 ± 21.25) or full stomachs (3. 33 ±16.62).