Corralation between snails and fish in fish ponds of world fish center [ICLARM] with spicial refernce to snail vectors of schistosomiasis and fascioliasis

ABSTRACT

The abundance of snail species in earthen fish ponds, irrigation and drainage canals at World Fish Center [ICLARM] in a descending order was Bellamya unicolor [50.89%] > Physa acuta [18.94%] > Cleopatra bulimoides [7.6%] > Lanistes carinatus [6.73%] > Bulinus truncatus [5.19%] > Melanoides tuberculata [4.83%] > Lymnaea natalensis [3.14%] > Gabbiella senaarensis [0.9%] > Biomphalaria alexandrina [0.55%] > Lymnaea truncatula [0.4%] > Planorbis planorbis and Succinea cleopatra [0.33%] > Ferrissia isseli [0.18%]. The dead snails constituted about 5.19% of all the collected specimens. There was a dramatic decrease in the total number of pulmonates in fish ponds, which contained only Tilapia sp., and a very small number of cat fish, whereas the numbers of Prosobranchia snails were much higher in these ponds. In fish Ponds, which accommodated a variety of fish species, the most dominant snail was B. unicolor, followed by L. carinatus. However, pulmonate snails were absent in these ponds. B. Truncatus was the only snail species found in concrete tank, which contained only young tilapias with a very small size [5-8 cm in standard length]. In irrigation canals, the number of snails and diversity was much higher than those in fish ponds. Out of 191 snails collected from inlet irrigation canal, 71 were dead, but in the outside irrigation canals, 7 out of 564 snails were dead. P. acuta was absent in all examined fish ponds, but it was alive and occurred in a high number [497 snails] in the outside irrigation canals. The number of snails collected from Bahnasawy drain was remarkably low [128 snails]; however, the diversity of snails was much higher compared with those in fish ponds and irrigation canals. Snail populations were stable with constant recruitment of young to adult snails for all the studied species