FACULTY OF VETERINARY MEDICINE

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Author: search.filters.author.Adeogun O. A.

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    Histopathological assessment of infested farmed Clarias gariepinus at various developmental stages in different culture management system
    (Alexandria: Faculty of Veterinary, Alexandria University, 2023) Okunade O. A.; Oladosu G. A.; Ajani E. K.; Adejinmi J. O.; Adeogun O. A.
    Parasitic infections infringe on different organs causing varying degrees of histological changes which contribute directly or indirectly to fish loss. Histological alterations play significant implication in fish health thereby proffer supports for effective diagnoses to improve the management of cultured fish. Various developmental stages of farmed Clarias gariepinus were randomly collected from 100 farms across the three agricultural zones (East, West and Far – East) in Lagos State, Nigeria from purposively classified culture systems based on water usage management systems (WUMS) into daily water renewal (DWR), weekly water renewal (WWR) and bi – weekly water renewal (BWR)). The organs (skin, gills and intestines) were selected for parasitological examinations and histological sectioning using standard procedure. The water qualities monitored were temperature, dissolved oxygen, pH, ammonia, nitrite, iron, alkalinity, hardness, and turbidity and measured using standard methods. Descriptive statistics such as frequency count, percentages, standard deviation were used to determine the occurrence and rate of histological changes in relations with parasitic infections while semi quantitative analysis was used to assess the histological lesion on gills. This study reveals possible relationship between parasitic infections and histological changes on the gills. The protozoans (Trichodina spp, Vorticella spp., Tetrahymena spp., Chilodonella spp., Piscinoodinium spp. and Ichthyobodo spp.) and monogenean trematode (Dactylogyrus spp., and Gyrodactylus spp.) were related parasites found with varying degrees of histological changes like hyperplasia of the epithelial cells, lifting of the primary epithelium, sloughing of the epithelium, fusion of the secondary lamellae, oedema of the lamellae, vacuolation of the epithelial cells, swelling of the epithelial cells, diffuse infiltration of lamina propria by neutrophil and necrosis of the secondary lamellae, classified into stages I, II and III. The most frequently observed histopathology in all the culture systems was hyperplasia of the gill lamellae; DWR-86.96%, WWR – 88.10%, BWR – 92.86%, followed by the fusion of the secondary lamellae; DWR-65.22%, WWR 75%, BWR– 78.57%. No histopathological change was observed on the skin and the intestine and lesions were least in the daily water renewal (DWR) culture system. Hence, it can be safely inferred that good management practice in terms of water renewal system should be encouraged to alleviate parasitic infections and minimize organ damage in cultured fish.
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    Investigation of Parasitic Crustacean in the Culture Management of Clarias gariepinus in Lagos Fish Farms
    (Alexandria: Faculty of Veterinary, Alexandria University, 2023) Okunade O. A.; Ajani E. K.; Adejinmi J. O.; Oladosu G. A.; Adeogun O. A.
    The major parasitic crustaceans infecting cultured fish species comprise Branchiurans, Leaneids, Ergasilids and Isopods causing wounds that serve as portal entry for bacterial, fungi and viral infections eventually result to morbidity, mortality and economic loss thereby necessitating investigation on prevalence and effects on predilection site of Clarias gariepinus in this study. Four hundred and eighty-four fish samples of Clarias gariepinus at various developmental stages were randomly selected from fish farms across the three agro – ecological zones in Lagos Stata, Nigeria. The samples collection lasted eighteen months covering both wet and dry season while parasitology and histology examinations were carried out in a laboratory using standard methods. The wet mounts were prepared for skin and gills. Water quality parameters monitored were pH, water temperature, dissolved oxygen, ammonia, nitrite, iron concentration, alkalinity, hardness, and turbidity according to respective manual guidelines. Descriptive statistics such as frequency count, percentages, standard deviation were used to determine the level of prevalence, occurrence, and distribution of the parasites. Argulus species (Branchiuran) was the only parasitic crustacean observed in this study with low prevalence and intensity of infection of 1.05% and 2 respectively found on the gills of fingerlings during the rainy season. The histological examination on infected gill revealed no alteration. The water parameters were within the acceptable limit for fish survival. The low prevalence and loads of Argulus sp indicated good management practices which possibly suppress the propagation of the parasites despite the expected influence of optimum temperature and low dissolved oxygen in favour of the parasites. Therefore, good management practices should be encouraged to reduce rate of parasitic infection that often being a primary pathway to secondary infections.