FACULTY OF VETERINARY MEDICINE
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Item Histology of selected organs of Clarias gariepinus infected with the metacercaria of a digenean trematode(Faculty of Veterinary Medicine, University of Ibadan (Ibadan, Nigeria, 2021) Adedokun, R. A. M.; Aina, O. O.; Oladosu, G. A.; Igado, O.O.; Tijani, I. D.Fish have become a major source of protein and essential fatty acid for fish lovers in the world. Thus, many farmers are venturing into fish farming but have challenges due to fish diseases and parasites. This study examined the possible pathological lesions associated with digenean trematode infections in the Clarias gariepinus. Clarias gariepinus juveniles reared in fibre-glass tanks under intensive, flow through system were obtained from a commercial farm. Aquatic snails were obtained from earthen ponds on three commercial fish farms. The presence of cercaria was established in these snails, which were reared in laboratory conditions with Clarias gariepinus juveniles, for two weeks, to cause infection. Age matched un-infected Clarias gariepinus served as controls. Presence or absence of metacercaria after histological examination was used to determine infected and controls, respectively. Fish were sacrificed after two weeks and organs reexamined for the presence and absence of metacercaria. Preliminary examination using wet mount revealed the presence of metacercaria only in the gills of juveniles reared with infected snails. Histological staining and examination using haematoxylin and eosin stain, revealed histopathological lesions in the gills, kidneys, liver, spleen, brain and skin. Lesions included loss of secondary filaments in the gills, tubular degeneration and necrosis in the kidneys, vacuolations and spongiosis in the cerebellum and liver, and loss of pigmentation in the skin. There were no lesions observable in the intestine and stomach. Findings obtained from this experiment indicate that the presence of parasites in the gills alone is cause for concern, especially in commercial fish farming. It is postulated that the lesions in other organs may be partly due to the disruptive effect on the gills resulting in oxygen deprivation. In conclusion, there was significant disruption of these organs due to massive invasiveness of metacercaria in the gills, which may lead to economic losses and possible zoonosis. Measures targeted at snail control in earthen ponds with fiches, will break the transmission chain, and prevent digenea infestation in cultured fish.Item Causal Factors of Mass Mortality of Hatchery Reared Clarias gariepinus fry during Exogenous Feeding(AkiNik Publications, 2021) Anifowose, O. R.; Oladosu, G. A.; Oladele, O. O.The 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 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 Performance of Clarias gariepinus in a polyculture with Oreochromis niloticus under the integrated broiler chicken/fish farming(Nigerian Institute for Oceanography and Marine Research, 1990) Oladosu G.A.; Ayinla, O. A.; Onuoha, G. C.; Needom, J. GA study of the performance of Clarias gariepinus (African Mudfish) in a polyculture with Oreochromis niloticus (Tilapia), integrated with broiler chicken production. was carried at the African Regional Aquaculture Centre, Nigeria. Three experimental treatments were utilized. Treatment I was a poly culture of C. gariepinus and O. niloticus integrated with broiler chicken production, with application of supple- mental feed to fish. Treatment II was a repeat of treatment I, except that no supple- mental feed was applied to fish, while treatment III was a polyculture of the two fish species per se with application of supplemental feed to fish. Results showed that the final individual weight, individual weight gain and recovery rate were best for C. gariepinus, under treatment I. Moreover, C. gariepinus yield in treatment II was 47.7% of that of treatment I, while yield in treatment III was 15.6% and 32.7% of those of treatments I and II respectively. Furthermore, the comparisons of the daily growth rate for each of the fish species under different treatments, were made. Statistical analysis showed that there is no difference (F7/0.10 and F7 0.05) in the mean growth rate and average yield of both fish species, in all the treatments. A further comparison of these parameters (mean daily growth rate and average yield) showed that there was significant difference in the mean daily growth rate between treatments I and III only, and in the mean yield between treatment I and II, I and !!! and II and III. Furthermore, the possible effect of some physicochemical parameters of the pond water, on the growth and survivability of the stocked fish species were discussed.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 Histology of selected organs of Clarias gariepinus infected with the metacercaria of a digenean trematode(University of Ibadan, Faculty of Veterinary Medicine, 2021) Adedokun, R. A. M.; Aina, O. O.; Oladosu, G. A.; Igado, O. O.; Tijani, I. D.Fish have become a major source of protein and essential fatty acid for fish lovers in the world. Thus, many farmers are venturing into fish farming but have challenges due to fish diseases and parasites. This study examined the possible pathological lesions associated with digenean trematode infections in the Clarias gariepinus. Clarias gariepinus juveniles reared in fibre-glass tanks under intensive, flow through system were obtained from a commercial farm. Aquatic snails were obtained from earthen ponds on three commercial fish farms. The presence of cercaria was established in these snails, which were reared in laboratory conditions with Clarias gariepinus juveniles, for two weeks, to cause infection. Age matched un-infected Clarias gariepinus served as controls. Presence or absence of metacercaria after histological examination was used to determine infected and controls, respectively. Fish were sacrificed after two weeks and organs re examined for the presence and absence of metacercaria. Preliminary examination using wet mount revealed the presence of metacercaria only in the gills of juveniles reared with infected snails. Histological staining and examination using haematoxylin and eosin stain, revealed histopathological lesions in the gills, kidneys, liver, spleen, brain and skin. Lesions included loss of secondary filaments in the gills, tubular degeneration and necrosis in the kidneys, vacuolations and spongiosis in the cerebellum and liver, and loss of pigmentation in the skin. There were no lesions observable in the intestine and stomach. Findings obtained from this experiment indicate that the presence of parasites in the gills alone is cause for concern, especially in commercial fish farming. It is postulated that the lesions in other organs may be partly due to the disruptive effect on the gills resulting in oxygen deprivation. In conclusion, there was significant disruption of these organs due to massive invasiveness of metacercaria in the gills, which may lead to economic losses and possible zoonosis. Measures targeted at snail control in earthen ponds with fiches, will break the transmission chain, and prevent digenea infestation in cultured fish.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 oxygen