FACULTY OF VETERINARY MEDICINE
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Item 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.Item 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.Item First Report and Prevalence of Sessile Ciliate (Vorticella sp.) in cultured Clarias gariepinus in Nigeria(the Fisheries Society of Nigeria (FISON), 2021) Okunade, O. A.; Ajani E. K.; Adejinmi J. O.; Oladosu G. A.Fish parasites commonly cause portal for secondary infections, hindering high productivity leading to economic loss in fish production. Protozoan parasites are a significant group of pathogens affecting cultured fish. The present study was carried out to investigate the prevalence of parasites infecting different stages of cultured Clarias gariepinus in Lagos State. A total of 487 cultured Clarias gariepinus were collected randomly from different culture facilities in culture systems and parasitological examinations were conducted on them. Identification keys with morphometric criteria were used to identify Vorticella sp from other sessile ciliates. Vorticella sp. was observed on the skin and intestine. It was found in all the culture systems and developmental stages. The highest prevalence for Vorticella sp. was found on adult skin (12.84%) and intestines (3.85 %). The mean intensity of Vorticella sp. was highest on fingerlings skin (23.88) and juvenile intestine (16). The mean water parameters showed a suitable range for their survival. This study is the first report of this sessile ciliate in Nigeria, indicating that more parasites are yet undiscovered in aquaculture.Item Identification and distribution of parasites on developmental stages of Clarias gariepinus reared in different water renewal culture systems(Department of Aquaculture and Fisheries Management, University of Ibadan, Nigeria., 2020) Okunade O. A.; Ajani E. K.; Adejinmi J. O.; Oladosu G. A.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 spp.); helminths (Dactylogyrus spp., Gyrodactylus spp., suspected Salmonichus spp. and unidentified nematode spp.) and crustacean (Argulus spp.). 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.Item Prevalence and intensity of parasitic infestation on developmental stages of Clarias gariepinus reared in different water renewal culture systems(Department of Aquaculture and Fisheries Management, University of Ibadan, Nigeria., 2020) Okunade O. A.; Ajani E. K.; Adejinmi J. O.; Oladosu G. A.Fish disease is a significant factor in aquaculture that causes negative impact. Therefore regular updates of epidemiological data must be ensured indicating the level of exposure to infections which prompted this study. 487 Clarias gariepinus comprising different developmental stages were collected from the water renewal systems; daily (DWR), weekly (WWR) and bi-weekly (BWR). The prevalence and mean intensity of infection were determined using standard parasitological methods. Water parameters were measured using recommended methods. Descriptive statistic (percentages and mean) was used for analysis. The parasites observed were protozoans - Trichodina spp., Vorticella spp., Tetrahymena spp Chilodonella spp., Ichthyobodo spp., Piscinoodinium spp., and Ambiphyra spp.; monogenean trematodes - Dactylogyrus spp., Gyrodactylus spp., and suspected Salmonichus spp.; crustacean parasites – Argulus spp. and unidentified Nematode. The highest prevalence and intensity of 80% and 55.50 ± 18.63 respectively were recorded in Trichodina spp infection in fingerlings, under the BWR. With Trichodina spp and Dactylogyrus spp prevalence of 80% and 40% on the gills respectively and 60% prevalence of Trichodina spp on the skin, the gills and the skin are the most preferred predilection sites for Trichodina spp, while Dactylogyrus spp has the gills as its main predilection site. The rate of single infection was higher than co-infection in all the culture systems for all developmental stages of C. gariepinus.