dc.description.abstract |
A crosssectional study on parasitic infections of fish was conducted from December 2011 to
May 2012 at Lake Tana to identify parasites of important fish species. The fish were sampled
from three different sites (South, East and West) of the lake and the sampling were taken at
morning time randomly on different boats and transported to the recommended laboratory by
cooler jar filled with water from the lake itself From the total of 1197 samples 924 (77.2%)
were infected, Labeobarbus species (n = 450, 52. 13%), Nile tilapia (Oreochromis niloticus)
(n = 477, 78.53%) and catfish (Clarias gariepinus) (n = 300, 18.63%) were examined using
standard laboratory techniques. From total number of fishs examined 450 (43.9%) were
males and 7 47 (71. 8%) females. Accordingly, the major parasite noticed during investigation
include the dominant encysted pleurocercoid with prevalence rate of (28.9%) followed by the
monogenean Clinostomum species (18.3%) and Contracaecum species larvae (17.8%). From
all organs examined, skin was highly infested by eight different types of parasites (11. 75) and
external crustacean, Dolops species (5.26%). The external protozoa (Trichodina species)
( 4. 5%) was found only in southern part of the Lake. Fish from the three areas were infested
with different parasite species and the southern partof the lake was found to harbour the
highest prevalence (150.4%) of parasitic infestations. The larval nematode Contracaecum
species had highest mean intensity of 3 in the South, 4 in West and 5 in East and with mean
abundance of 0.15, 0.63 and 0.58, respectively. Further assessment of parasites in thier
intermediate and final hosts like piscivorous birds as well as in humans is paramount
important. |
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