Occurrence of larval contracaecum (nematoda: heterocheilidae) in three teleostean fish species from lake Naivasha, Kenya
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Date
2001
Authors
Aloo, P. A.
Journal Title
Journal ISSN
Volume Title
Publisher
Faculty of Science Kenyatta University
Abstract
Occurrence of the larval nematode (Contracaecum sp.) in three teleostean species, viz:
Oreochromis leucostictus (Trewavas), Micropterus salmoides (Lecepede) and Tilapia zillii
(Gervais) in Lake Naivasha was investigated over a period of 12 months (September 1996 -
August 1997). The/ work was carried out to establish the seasonal prevalence, variation in
intensity of infection with size, sex and sampling stations and the effect of the parasite on the
health status of the three hosts.
Results indicate that there was no significant monthly variation in the intensity of infection in
the three fish species (P>0.05) and both males and females showed no significant difference in
the rate of infection by the larval nematode. Oreochromis leucostictus was observed to be the
most heavily infected (Mean parasite load = 15) while Tilapia zillii was the least infected
(mean parasite load = 2)
Infection rate and parasitic load between length classes were very significant in 0. leucostictus
(X2
3 = 212.7; P<O.OOI), M salmoides (X2
3 = 12.93; P<O.OOI) but not in T. zillii (P>0.05). There
was however, a great variation in infection rate within sampling sites in all the three species; 0.
leucostictus (X2
4 = 20.66; P<O.OO1), T. zillii (X2
4 = 12.10; P<0.05) and in M salmoides (X2
4 =
18.89; P< 0.0 I). The nematode had no apparent effect on the well-being of the fishes as there
was no significant relationship between condition factor and parasite load (P>0.05).
Description
Research Article
Keywords
Contracaecum, Lake Naivasha, parasite, nematode, fish
Citation
East African Journal of Science 3(1): 1-12 (2001)