FIELD STUDIES ON THE EFFECT OF THE FISHES OREOCHROMIS NILOTICUS AND HAPLOCHROMIS DESFONTAINESI ON VECTOR SNAILS IN EARTHEN FISH PONDS AND NATURAL HABITAT IN EGYPT | ||||
| Journal of Biological Chemistry and Environmental Sciences | ||||
| Volume 3, Issue 1, March 2008, Page 939-961 PDF (622.73 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/bces.2008.426877 | ||||
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| Abstract | ||||
| Field studies were conducted at 7 earthen fish ponds (fish hatchery at Al-Abbassa, Sharkia Governorate) used for breeding the fish Oreochromis niloticus to survey both vector and non vector snails in fish ponds and to determine the efficiency of fish against snail vectors. The results indicated that snails belonged to eight species, in descending order: Bellamya unicolor (51.3%) > Physa acuta (25.3%)> Gabbialla senaariesis (10.3%)> Cleopatra bulimoides (4.9%)> Bulinus truncatus (3.3%)> Lansists carinatus (1.9%)> Melanoides tuberculate (1.9%)> Lymnaea cailliaudi (1.1%). Ponds which contained young fish accommodated higher snails diversity than those contained parent fish. Also, stomachs of specimens of O. niloticus collected from fish ponds were examined for the purpose of studying their food with emphasis given to vector snails. Results of the index of relative importance (I.R.I.) emphasized the importance of artificial fish food as a major food resource (8090.3) followed by snails (3880) and then insects (382.3). Seasonal variation in the composition of the diet showed that snail shell parts were the major food category in the diet during summer (43%), and reached the lowest level during winter (2%). In contrast, the artificial fish food was recorded as the highest proportion in the diet during winter (58%) decreased remarkably during spring (33%) and summer (35%) but increased again in autumn (56%). In addition, stomachs of the fish specimens of Haplochromis desfontainesi and O. niloticus collected from Ismailia irrigation canal FIELD STUDIES ON THE EFFECT OF THE FISHES940 were examined to investigate the nature of the diet with emphasis given to vector snails. Results of the I.R.I. indicated that snails were the second important food items in the diet of both species. Snails were present in the diet of H. desfontainesi in all seasons; however, they exhibited marked seasonal variation in abundance with maximum level during spring. They reached the highest level in the diet of O. niloticus also during spring decreased during summer and remained at the same level during autumn until disappeared in winter. | ||||
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