FACULTY OF VETERINARY MEDICINE
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Item Detection of Saprolegnia species on incubated eggs of Clarias gariepinus (Burchell 1822) using morphological and molecular characterization(Association of Nigerian Fisheries Scientists (ANIFS), 2019) Fagbohun O. A.; Oladosu G. A.Fungal infection of incubated eggs suspected to be one of the causal factors of poor hatching rates was studied on eggs collected from selected hatcheries in Ibadan, Nigeria. Morphology of the hyphae and the reproductive organs of fungus isolated with Sabouraud dextrose agar (incubated at 25°C for 48 hours) was conducted. Also, polymerase chain reaction (PCR) was used to detect and amplify the internal transcribed spacer 2 (ITS-2) and 5 'end region of 28S (D1-D2 region) of ribosomal RNA genes of the fungus. Hyphae and reproductive organ structures observed were typical of Saprolegnia spp.. while the PCR amplified the target nucleotide sequence in the fungal isolate. These findings confirmed the involvement of Saprolegnia spp. in mycosis commonly observed in incubated catfish eggs, and should be considered in the control of poor egg hatching rates and mass mortality of hatchlings and fry.Item Technical report on hatcher partnering; A UKaid sponsored aquaculture intervention program of Convention on Business Integrity (CBI) in Kwara state, Nigeria.(2017) Oladosu G. A.African catfish species that comprise of Clarias gariepinus, Heterobranchus longifilis, Heterobranchus bidorsalis and their reciprocal hybrids are the predominantly cultured species in Nigeria. The massive adoption of intensive rearing systems including the water recirculating and the water flow-through production systems has further enhanced productivity, promoting catfish culture to a full fledge industry in Nigeria. However, preponderance of catfish hatcheries established by untrained hands has resulted in the production of poor quality seeds (fingerlings and juveniles), and low productivity due to heavy mortality that most hatchers are unable to handle. An earlier BIF study lend credence to these developments, with the consequence of poor productivity by Small Scale Fish Farmers (the final up-takers of the poor quality seeds), and the danger of the industry becoming unsustainable.Item Completion report on technical training in best hatchery management practices for hatchery operators in the Niger-Delta(USAID | NIGERIA, 2017) Oladosu G. A.This training program for capacity building in hatchery management was proposed to mitigate skills gap earlier observed during the technical assessment of catfish hatcheries in the Niger Delta for infrastructural upgrade that was conducted in 2014. Of the twelve (12) catfish hatcheries selected for facility upgrade, eight (8) were empowered with production facilities following competitive bidding, while the entire twelve (12) were recalled to provide two (2) persons for capacity building in best hatchery management practices. However, only twenty-two (22) out of the expected twenty-four (24) participants attended the training program, as two (2) farms namely Zezi farms, Benin, Edo State and Segfun farms Calabar, Cross River State were represented by one trainee each. Pre-training evaluation conducted to determine the areas of critical deficiencies revealed the need to improve skills in all areas of controlled catfish propagation since challenges indicated by participants as intractable for them cut across all areas of controlled fish breeding. The modules for the training that took place in Port-Harcourt, Rivers State, between the 16th and 19th of May 2017, comprised of technical and practical sessions. Seven (7) technical sessions (TS) were delivered in a 67 slides power point presentation at Sparklight Hotel, GRA Phase 3, and seven (7) hands-on, practical sessions (PS) were conducted in the hatchery of Mayuel Fisheries belonging to one of the trainees. Controlled spawning of Clarias gariepinus by the dry stripping method was carried out at Mayuel Fisheries, Port-Harcourt using male and female broodstock procured from another farm within Port-Harcourt metropolis. All aspects of seed propagation techniques such as broodstock selection, induction of ovulation, milt procurement, fertilization, egg incubation, fry nursing, fry rearing, biosecurity and disease control were demonstrated within the 4-day period of training. In their post training evaluation, the trainees adjudged both the technical and the practical sessions as timely, appropriate and excellently delivered, providing insights that will be helpful in overcoming their challenges, since errors of the past were fully exposed and addressed. Some recommendations were made in the action plan drawn by the trainees to round-up the training programItem Aquaculture practice in management of fish disease and biosecurity(Department of Aquaculture and Fisheries Management, University of Ibadan, Nigeria., 2015) Akinwole A. O.; Oladosu G. A.; Ajani E. K.Item Item Report on clinical, bacteriological and pathological investigations of mass fish kill at the Lagos State Fish Farm Estate, Ikorodu(2014) Oladosu G. A.; Adedeji O. B.; Tijani O. M.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 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.