Identification and Distributions of Parasites on Developmental Stages of Clarias gariepinus Reared in Different Water Renewal Culture Systems

Abstract

The intensification and commercialization of fish production often cause an imbalance in the water environment thereby exposing them to stress and biological pathogens – parasites, bacteria, fungi and viruses. Parasites are the primary causative agent of infections forming pathways for secondary infections whereas the knowledge about identification and distribution of parasites is vague to most farmers which prompted this study. The population size was 3% of functioning farms where five live fish were randomly collected from water renewal culture systems (Daily (DWR), Weekly (WWR) and Bi-weekly BWR)) for parasitological examination. Relevant keys were used for parasite identifications. Water parameters were measured for the community of parasites using standard methods. Descriptive statistics (percentages and mean) were used for analysis. The parasites observed across the culture systems in this study were categorized into three groups – protozoans (Trichodina spp., Vorticella spp., Tetrahymena spp., Chilodonella spp., Ichthyobodo spp., Piscinoodinium spp., and Ambiphyra sp); helminths (Dactylogyrus spp., Gyrodactylus spp., suspected Salmonichus spp., and unidentified nematode spp.,) and crustacean (Argulus sp.). Trichodina spp., Vorticella spp., and Dactylogyrus spp., parasitized all developmental stages (fry, fingerlings, juveniles and adults) collected from DWR and WWR. Trichodina spp.was highly distributed on the skin (66%) and gills (84.5%) in BWR; Vorticella spp.on the skin (29.4%) and predominantly dominated the intestine (100%) in WWR; Dactylogyrus spp.was on the skin (2.5%) and gills (36.8%) in DWR. No Vorticella spp.and Dactylogyrus spp., were recorded on gills and intestine respectively across the culture systems but nematode spp was predominantly found in the intestine. Therefore, the presence of parasites in all the culture systems and developmental stages indicates that neither a system nor developmental stage is exempted thereby more attention should be given to fish hygiene, especially with the awareness of different species of parasites in fish farms.