FACULTY OF VETERINARY MEDICINE
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Item Size variation, growth and body conformation of reciprocal hybrids of Clarias gariepinus (Burchell 1822) and Heterobranchus bidorsalis (Geoffroy, 1809).(Nigerian Institute for Oceanography and Marine Research, 1996) Uka A.; Oladosu G. A.; Ayinla O. A.Reciprocal hybrids of Clarias gariepinus and Heterobranchus bidorsalis were compared for size variation, growth and body conformation. Growth was observed to be significantly faster (P<0.05), and size variation less pronounced (CV = 26%) for C. gariepinus (female) and H. bidorsalis (male) hybrid, than the reciprocal (CV=38%) No difference was observed in the body conformation between the reciprocal hybrids. However, the percent head length of the standard length was significantly smaller (P<0.05) in the reciprocal hybrids than that observed for the parent species.Item Pathogenicity of Aspergillus fumigatus in experimental infection of different developmental stages of Clarias gariepinus(Science domain International, 2023) Owolabi M. O.; Anifowose O. R.; Oladosu G. A.; Wolabi O. O.Aims: This study aimed to investigating the pathogenicity of Aspergillus fumigatus in the experimental infection of Clarias gariepinus fingerlings and juvenile catfish. Experimental Procedure: Aspergillus fumigatus used for this study was isolated from the gills and liver of infected juveniles presented for microbial diagnostic examination, cultured on Sabouraud dextrose agar for 3 – 4 days, and identified at the Aquatic Animal and Wildlife Laboratory (AAWL), Department of Veterinary Medicine, University of Ibadan. Methodology: One hundred and forty healthy eight-week old Clarias gariepinus fingerlings (average weight of 4g) and 140 healthy sixteen-week old juvenile (average weight of 10g) were purchased from a commercial fish farm in Ibadan. The fingerlings and juveniles were randomly divided into seven groups, each with 20 fish in five litters of water. The fungal suspension containing 3.2 X 106 spores/ml of Aspergillus fumigatus was used for the pathogenicity test. Six groups were infected by immersion in water containing fungal spores at the rates of 2ml/L and 5ml/L for fingerlings and juveniles respectively. The clinical signs, skin lesions and mortality were observed daily for 14 days. Results: Aspergillus fumigatus isolated in this study has green spiked conidia; and the size of the conidia is 2.5µm. The conidia have a smooth surface and small spikes covering their surface. Moreover, the mortality rate was significantly (p = 0.40) higher in infected fingerlings (80%) than juveniles (62%) at fourteen days post-infection. The gross lesions observed during experimental infection of fingerlings and juveniles included exophthalmia, atrophied barbel, congested trunk kidney, hyperemia of gill filaments, and skin depigmentation. The histopathological organ changes caused by Aspergillus fumigatus were obvious in the liver and gills. Vacuolar degeneration of hepatocytes and necrosis of some melanomacrophage cells, in addition, severe erosion of the primary and secondary lamellae, were observed in infected juveniles. Conclusion: Aspergillus fumigatus causes high mortality in fingerlings and juvenile of African Catfish (Clarias gariepinus).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 Comparative growth performance and survival of hatchery reared African catfish fry (Clarias gariepinus Burchell 1822) fed on live and artificial diets(Akinik Publications, 2022) Anifowose O. R.; Oladosu G. A.; Oladele, O. O.Background: Feed determines to a large extent the sustainability in aquaculture since the survival and growth of the fish fry depends on the quality of feeds. The comparative growth performance and survival in Clarias gariepinus fry fed with live and artificial feeds were carried out. Methods: Four hundred and eighty healthy fries collected from a commercial hatchery were randomly divided into four experimental groups of 40 fry with three replicates for each group, and fed with four different feeds (three live feeds and one artificial feed) to differentiate each group; Artemia Lush® (AL), Artemia Inve® (AI), Dried-ground Shrimp (S), and artificial feed Durante® (D) for three weeks. The proximate composition of feed samples was analyzed, Physico-chemical parameters and microbiological analysis of water in experimental tanks were analyzed on weekly basis. The fish were assessed for growth performance and survival on weekly basis. Results: There was a significant difference of P< 0.05 in all proximate compositions of the feeds analyzed, there was no significant difference (P> 0.05) in the Physico-chemical parameters of water in the experimental tanks within twenty-one days. The final weight, final length, specific growth rate, and survival of fry fed with live feeds Artemia were similar to artificial feed Durante® but the economic analysis was reduced in artificial feed compared to live feeds while fry fed with Dried-ground Shrimp had poor growth and survival rate. Conclusion: The feeding of live and artificial feeds to Clarias gariepinus fry within the first twenty-one days produced a similar growth response and survival rate but artificial diet required reduced cost than live diets while dried-ground shrimp should not be recommended for feeding Clarias gariepinus fry.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 Causal Factors of Mass Mortality of Hatchery Reared Clarias gariepinus fry during Exogenous Feeding(AkiNik Publications, 2021) Anifowose O. R.; Oladosu G. A.; O. O. OladeleThe study investigated the causal factors associated with mass mortality of hatchery-reared Clarias gariepinus Burchell 1822 fry during exogenous feeding. A feeding trial and fry re-infection trial were conducted using four different starter diets. The food samples were fed to 480 post-yolk-absorbed fries for 21 days in two replicates. Samples of dead fry were cultured for bacteria using standard methods. The total aerobic and coliform were significantly higher in all food samples, meanwhile, alkaline pH (9.25±0.34) and low dissolved oxygen (4.5±1.08) were not significantly different (P>0.05) in all water tanks. The bacterial pathogens isolated from dead fries were Aeromonas hydrophila Stainer, 1943 and Pseudomonas aeruginosa Migula, 1990, whereas significantly higher mortality in experimentally infected fry was observed (α < 0.05). Mass mortality of C.gariepinus fry observed in this study was associated with bacterial pathogens, bacterial contamination of food, alkaline pH, and low dissolved oxygenItem 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.Item Pathogenicity and antibiotic sensitivity profile of Aeromonas bestiarum used in experimental infection of different developmental stages of Clarias gariepinus(Kosmos Publishers, 2020) Tiamiyu O. S.; Oladosu G. A.; Anifowose A. R.; Ajayi O. L.Motile Aeromonas Septicaemia (MAS) known to be the commonest bacterial infection of cultured fish is mostly ascribed to Aeromonas hydrophila. This study was therefore conducted to determine the pathogenicity of Aeromonas bestiarum in fry, juvenile and post-juvenile of Clarias gariepinus, and evaluate the antibiotic sensitivity profile of the organism for effective control. Aeromonas bestiarum was isolated from dead fry in ljebu Ode. The organism was characterized and used for this study. Two-hundred apparently healthy fry collected from a commercial hatchery were randomly divided into four experimental groups of 50 fry. One hundred and twenty apparently healthy juvenile and post juvenile collected from a commercial hatchery were randomly divided into four experimental groups of 15 juvenile and post juvenile respectively. Three groups were infected with 1x108 (cfu)/ml of Aeromonas bestiarum by immersion in 21 of water, while the fourth group were not infected. Fish in the infected and control groups were monitored daily for 21 days for signs of infection and mortality. The cumulative mortality in fry, juvenile and post-juvenile were 85%, 82% and 50% respectively. Gross lesions observed in post-juvenile fish were bulgy eyes, swollen dorsal muscle caudal to the cranium, congested kidney and skin depigmentation. Histological lesions were equally recorded in the hepatic tissue. diffuse degeneration and necrosis of the tubular epithelium in the interstitium of kidney. It was re-isolated from infected fish in the different developmental stages, while the organism was observed to be sensitive to two antibiotics. Groups of survivors in the different stages were treated for five days. On the second day of treatment, there was 15%, 14% and 0% mortality in the treated fry, juveniles and post-juveniles respectively, while the mortality rate of untreated but infected group (control) were 40%, 42% and 42% for fry, juveniles and post-juveniles fish respectively. This shows Aeromonas bestiarum causes high mortality in fry, juvenile and post- juvenile of Clarias gariepinus. It's however sensitive to Enrofloxacin and Gentamicin which can be used for treatment of infection by Aeromonas bestiarum for now.Item An assessment of the pathogenicity of Edwardsiella tarda and treatment of experimental edwardsiellosis in cutured Clarias gariepinus (Cuvier 1822)(Fisheries and. Aquatic Science, 2016) Oladosu G. A.; Olufemi B. E.; Ighara O.The pathogenicity of Edwardsiella tarda isolated from pond water, and chemotherapeutic control of experimental edwardsiellosis in cultured Clarias gariepinus were investigated. The E. tarda isolate was identified based on colony and cellular morphology, as well as biochemical characteristics. A total of 120 fish were randomly assigned to four groups (A, B, C and D) of 30 fish, each comprising of 15 fish replicated once. Fish in groups A, B and C were infected intra-peritoneally with 1.02x10 cfu of E tarda, while group D was not infected. Following observation of clinical signs, group A was treated with ciprofloxacin by 1hour immersion at 25mg/litre of water and group B orally at 100mg/kg body weight of fish for five days. Fish in group (C) were not treated with ciprofloxacin. Fish were observed for mortality daily, and cumulative mortality was compared between groups using ANOVA and Duncan Multiple Range Test. Cumulative mortality of 56.66% observed in group C was significantly higher (p < 0.05) than in groups A and B treated via oral (3.33%) and immersion (3.33%) route respectively. Infected fish were effectively treated by both routes of ciprofloxacin application, but the oral route is considered less stressful for the sick fish.