A Survey of Gill Histopathology of Thirteen Common Fish Species in the Sanyati Basin, Lake Kariba, Zimbabwe/ Badania Histopatologiczne Skrzeli Trzynastu Pospolitych Gatunków Ryb W Zlewni Sanyati, Jezioro Kariba, Zimbabwe

Background: Hydrocynus vittatus and Oreochromis niloticus are two economically important fish species in Zimbabwe. The length-weight relation can be employed to assess the health and well-being of fish so as to assist fish farmers. The objective of the study was to investigate the length-weight relationship and condition factor of these fish species. Methods: Thirty-four fish of each species (Hydrocynus vittatus and Oreochromis niloticus) were collected by seine netting in the Sanyati Basin, Lake Kariba in August 2019. The total length (TL) and standard length (SL) were measured in centimetre (cm), and the body weight (BW) was measured in grams (g). The body weight (BW) was measured using a digital top-loading electronic weighing balance. Results: The value of the exponent b in the LWR for H. vittatus was 2.984, indicating negative allometry (b<3). The exponent value of O. niloticus in the LWR was 3.04 (b>3) implying positive allometry. The r2 values for H. vittatus and O. niloticus were 92.3% and 97.3% respectively, indicating that there was a high degree of positive correlation. The condition factor for both fish species were greater than 1.60 implying good physiological conditions for both fish species. Conclusions: This study provides preliminary information on length-weight parameters of O. niloticus whose data was previously not available in the take.

Various oxidative stress and histopathological biomarkers in gill tissues of Nile tilapia Oreochromis niloticus were investigated. Fish were collected from four sites that differ in their extent of pollution load, including heavy metals: the southeast basin (SEB), main basin (MB), and northwest basin (NWB) of Lake Mariut; and Boughaz El-Maadiya, a channel in Lake Edku. The oxidative stress biomarkers that were analyzed included lipid peroxidation (LPO), superoxide dismutase (SOD), catalase (CAT), and glutathione redox cycle enzymes (glutathione peroxidase [GPx] and glutathione reductase [GR]). Levels of reduced glutathione (GSH) were also evaluated. Gill morphology was analyzed by light microscopy and scanning electron microscopy (SEM). Gill LPO was significantly higher in gill tissues of fish collected from the more heavily contaminated MB (40.0%) and NWB (51.4%) sites than in gill samples from the less-contaminated (reference) site, the SEB. Gill LPO in fish from Lake Edku was intermediate but was not significantly higher (17.1%) than the reference. The activities of antioxidant enzymes and the redox-sensitive thiol compound GSH were significantly lower in gill samples from the disturbed sites than in samples from the reference site. Specifically, SOD in MB, NWB, and Lake Edku samples; CAT and GPx in NWB samples; and GR activity and GSH content in MB and NWB samples were lower than those in SEB samples. In most cases, gill tissues from Lake Edku fish had intermediate levels of antioxidants. The main histopathological alterations observed in gills were epithelial lifting, hyperplasia and hypertrophy of the respiratory epithelium, lamellar fusion, and aneurysms. In addition, SEM results demonstrated transformation of the surface structure of epithelial pavement cells. Pathological reactions in the gills of Nile tilapia were most severe at the MB and NWB sites. Our findings suggest that Nile tilapia responded differently according to the environmental stress index in each sampling area. This study is the first to report gill oxidative stress and histopathologies in Nile tilapia from Egyptian aquatic environments.

Aims: The widespread use of Profenofos, an organophosphate pesticide, in agriculture, has raised concerns about its ecotoxicological effects on aquatic ecosystems. This study investigates the impact of Profenofos on the gill morphology of Channa gachua, a freshwater fish species, using scanning electron microscopy (SEM) to elucidate ultrastructural changes. Study Design: Healthy specimens of Channa gachua (dwarf snakehead) were collected from local freshwater bodies. The average length and weight of the fish were 12–15 cm and 20–25 g, respectively. Channa gachua specimens were exposed to sublethal concentrations of Profenofos (0.5 mg/L and 1.0 mg/L and 2.0 mg/L) for 21 days, and gill tissues were subsequently analyzed to assess morphological alterations. Methodology: Channa gachua were exposed to sublethal Profenofos concentrations (0.5mg/L, 1mg/L and 2 mg/L) for 21 days. Gill tissues were dissected, fixed in 2.5% glutaraldehyde, and dehydrated using an ethanol series. The samples were critical-point dried, gold-coated, and analyzed using scanning electron microscopy (SEM) to assess ultrastructural changes. Morphological alterations, including epithelial lifting, lamellar fusion, and mucus secretion, were quantified. Statistical analysis compared damage severity between control and treated groups. Results confirmed Profenofos as a critical stressor, highlighting its detrimental effects on gill ultrastructure. Results: SEM analysis revealed significant Profenofos-induced damage to the gill architecture of Channa gachua. Key observations included the distortion of primary and secondary lamellae, epithelial lifting, and rupture of microbridges. These structural deformities were dose-dependent, with higher concentrations of Profenofos causing more severe damage. The fusion of lamellae and epithelial lifting was particularly pronounced, suggesting impaired respiratory and osmoregulatory functions. Additionally, the presence of mucus secretion and cellular debris on the gill surface indicated a stress response to the toxicant. The ultrastructural changes observed in this study highlight the detrimental effects of Profenofos on gill tissue, which could compromise the fish's ability to maintain physiological homeostasis. The damage to the gill epithelium likely hinders oxygen exchange and ion regulation, potentially leading to hypoxemia and osmoregulatory imbalance. These findings underscore the role of Profenofos as a critical stressor in aquatic environments, with implications for the health and survival of fish populations. Conclusion: This study provides compelling SEM-based evidence of Profenofos-induced gill pathology in Channa gachua, emphasizing the need for stricter regulation of organophosphate pesticides to protect aquatic biodiversity. The results contribute to a deeper understanding of the ecotoxicological impacts of Profenofos and highlight the importance of using advanced imaging techniques like SEM to assess environmental stressors on aquatic organisms’ invasive independent predictors for screening esophageal varices may decrease medical as well as financial burden, hence improving the management of cirrhotic patients. These predictors, however, need further work to validate reliability.

Efficacy of the dehydrated lemon peels on the immunity, enzymatic antioxidant capacity and growth of Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus)

Simple SummaryAquaculture faces major challenges related to intensive farming, disease outbreaks and environmental stressors that compromise fish health and product quality. Bee-derived products such as pollen, bee bread, propolis, royal jelly, honey and fermented derivatives are rich in bioactive compounds with antioxidant, antimicrobial and immunostimulant properties. Recent studies in species like Nile tilapia (Oreochromis niloticus), rainbow trout (Oncorhynchus mykiss), European sea bass (Dicentrarchus labrax), meagre (Argyrosomus regius), and African catfish (Clarias gariepinus) demonstrate that dietary inclusion of these natural supplements can enhance growth, immune responses, stress tolerance and even the nutritional profile of fish flesh. For example, bee pollen at 10–30 g kg−1 increased growth by ~45% in African catfish, and a 25 g kg−1 pollen diet yielded up to 93% protection of Nile tilapia against Aeromonas hydrophila infection; in trout, pollen-derived carotenoids increased fillet carotenoid content (≈0.50–0.60 vs. 0.31 mg β-carotene eq kg−1 in controls), albeit with lower pigmenting efficacy than synthetic astaxanthin. Nevertheless, results are still fragmented and vary depending on product type, dose and origin. By reviewing current evidence and highlighting critical gaps, this work explores how bee products may support nutritional strategies that improve fish resilience, disease resistance and overall sustainability in aquaculture systems.Aquaculture is expanding rapidly worldwide, but its sustainability is threatened by intensive production practices, environmental stressors and recurrent disease outbreaks. Natural feed additives are increasingly studied as alternatives to antibiotics and synthetic compounds. Among them, bee-derived products—pollen, bee bread, propolis, royal jelly, honey and fermented derivatives—represent a promising resource due to their richness in proteins, amino acids, fatty acids, vitamins, flavonoids and phenolic compounds with demonstrated antioxidant, antimicrobial and immunostimulant properties. Evidence from studies on species such as Nile tilapia, rainbow trout, European sea bass, meagre and African catfish indicates that dietary supplementation with bee products can improve growth performance, immune and antioxidant responses, stress tolerance and resistance to bacterial infections while, in some cases, enhancing the nutritional value and shelf-life of fish products. Prominent examples include ~45% higher growth in African catfish with 10–30 g kg−1 bee pollen, up to 93% protection in Nile tilapia fed 25 g kg−1 pollen against Aeromonas hydrophila, and increased trout fillet carotenoids with pollen-derived pigments (with overall growth unchanged and pigmentation lower than synthetic astaxanthin). Conversely, meagre fed 20–40 g kg−1 raw pollen showed reduced growth and digestibility with elevated intestinal stress markers, underscoring species- and dose-specific responses. Nevertheless, the available data remain fragmented and heterogeneous, reflecting differences in product type, origin, dosage and experimental design. This review critically analyses the current knowledge on bee products in aquaculture nutrition, identifies the main gaps and limitations, and outlines future research directions. By linking fish physiology, nutritional strategies and product quality, bee-derived products emerge as innovative tools for promoting fish health and resilience in sustainable aquaculture.

Background: Fish is known to be one of the cheapest sources of animal protein and have essential nutrients needed in human diets. The present study investigated the proximate and nutrient composition of three species of fish, Champsocephalus gunnari, Oreochromis niloticus, and hybrid catfish (Clarias gariepinus). Methods: The sample collection, proximate and mineral analysis were conducted using the standard protocols of sample collections and chemical analysis. Results: The results revealed that Champsocephalus gunnari, Oreochromis niloticus, and Clarias gariepinus contain moisture (66.00±0.50%, 52.00±1.00%, and 70.00±0.20%), crude protein (9.20±0.1323%, 3.75±0.02%and 5.80±0.05%), crude lipid (10.16±0.91%, 2.37±0.01% and 12.00±0.30%), ash (11.92 ±0.02%, 39.40±0.03% and 11.97±0.06%), and crude fiber (2.03±0.01%, 2.36±0.02% and 0.19±0.01%) respectively. The mineral contents were: iron (4.50±0.01mg/kg, 3.70±0.01 mg/kg and 4.70±0.02mg/kg), Zinc (2.35±0.01mg/kg, 2.15±0.0100mg/kg and (1.89±0.01mg/kg) for Champsocephalus gunnari, Oreochromis niloticus, and Clarias gariepinus respectively, while copper was only detected in C. gunnari (0.25±0.01mg/kg). The same amount of chromium (0.01±0.00 mg/kg) was detected in all the samples. Manganese was undetected in all the samples. Conclusion: In conclusion, the present study demonstrated the nutritional value of Champsocephalus gunnari, Oreochromis niloticus and Clarias gariepinus. This information would help in choosing any of the fish bases on their nutritional values rather than taste and other physical features.

Assessment of the water quality, the human health risk, and heavy metal accumulation in Nile tilapia and African catfish collected from the Kitchener Drain-Egypt

Freshwater fish species harbour parasitic organisms, serving as either intermediate or definitive hosts for parasites that can be harmful to humans and animals. This study was conducted to assess the prevalence of parasites in two fish species obtained from selected farms in Calabar, Nigeria. Collection, examination, sex determination, and identification were performed using the recommended procedures. A total of 300 fish samples from four fish farms were examined for parasites, and 88 (29.3%) were found to be infected. The highest prevalence of parasitic infection was observed at the Nyahansang fish farm (41.3%), whereas the lowest prevalence was recorded at the University of Calabar (UNICAL) fish farm (18.7%). Gyrodactylus sp. (8.3%) were the most prevalent parasites, followed by Trichodina spp. (6.7%); Dactylogyrus sp. (4.7%); Aeromonas sp. (3.0%); Eustrongylides sp. (2.3%); Henneguya pinnae (2.3%); Ergasilus labracis (1.3%); and Chilodonella sp. (0.7%). Oreochromis niloticus had the highest parasite prevalence (54 [36.0%] ) compared to that of Clarias gariepinus(34 [22.7%] ). The prevalence of parasites was higher in females (31.4 %) than males (27.2%). In O. niloticus, 25 males (34.2%) and 29 females (37.7%) harboured parasites, but the comparison between sexes showed no significant difference (p>0.05). Similarly, in C. gariepinus, 15 males (20.3%) and 19 females (25.0%) harboured parasites, with no significant difference observed between the sexes (p>0.05). This study revealed the considerable prevalence of parasitic infections in the two fish species used. The results of this study highlight the potential risks posed by parasites on aquaculture, fish health, and economic sustainability. A deeper understanding of these parasitic dynamics is crucial for enhancing fish health, improving aquaculture productivity, and fostering sustainable fish farming practices in Nigeria.

Fish is an important source of long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) and also a good source of protein. Ethiopian lakes harbor a rich fish biodiversity which vary in their nutrient composition. This review will examine published data on the proximate and fatty acid content of six fish species from various Ethiopian Lakes. The fish species include the Nile tilapia (Oreochromis niloticus) , African sharp tooth catfish (Clarias gariepinus) , Nile perch (Lates niloticus) , Barbs (Barbus sp.) , Redbelly tilapia (Tilapia zillii) and Common carp (Cyprinus carpio) . Species were selected based on their current commercial importance as well as their potential for nutrition. The content of protein, fat, moisture and ash ranged from 13.30 to 18.50%, 0.40 to 2.45%, 77.24 to 80.80% and 0.81 to 1.20%, respectively. The fatty acid content of the fish ranged from 6.42 to 25.01 mg.g -1 dry weight (DW) for saturated fatty acids (SFA), 2.02 to 24.62 mg.g -1 DW for monounsaturated fatty acids (MUFA) and 7.88 to 24.12 mg.g -1 DW for PUFA. Among the SFA, palmitic acid was the main fatty acid while oleic acid and docosahexaenoic acid (DHA) were the main MUFA and PUFA respectively. The highest content of eicosapentaenoic acid (4.74 mg.g -1 DW) was found in Barbs from Lake Langeno while the highest docosapentaenoic acid (3.99 mg.g -1 DW), DHA (11.53 mg.g -1 DW) and total n-3 PUFA (20.61 mg.g -1 DW) were found in Nile tilapia from Lake Haiq. The n-3/n-6 ratios ranged from 1.39 to 5.86 mg.g -1 DW, with the highest ratio coming from Nile tilapia collected from Lake Haiq and the lowest from Redbelly tilapia from Lake Ziway. In conclusion, all the species collected from different Lakes of Ethiopia may be beneficial to human health. However, Nile tilapia from Lake Haiq and Barbs from Lake Langeno are the best for consumption due to higher levels of LC n-3 PUFA.

The nutritional status of fish is essential for its health, experimental studies, and aquaculture practices. The current study investigated the impact of food deprivation on biochemical parameters, histology of skin, gill, and kidney tissues, and ultrastructure of gills in Clarias batrachus. Fish were subjected to food deprivation for 2, 7, and 15 days resulting in (a) significant increase in plasma cortisol levels, (b) no significant changes in plasma osmolality and plasma glucose content, and (c) significant decrease in liver and muscle glycogen contents. A substantial damage was detected in skin, gill, and kidney tissues with histological alterations in a time-dependent manner. Skin tissue displayed melanomacrophage aggregation, excoriated epidermis and dermis. In gill tissue, epithelial lifting, edema, desquamation, deformed secondary lamellae, and lamellar hyperplasia were observed. Kidney tissue exhibited degenerated tubules, melanomacrophage aggregations, and shrunken renal tubule. Scanning electron microscopy revealed that food deprivation-induced marked presence of mucus, chloride cells, and pavement cells with well-defined microridges and microbridges following 2 days, opening of chloride cells was more prominent after 7 days, while more mucus secretion was observed after 15 days. After food deprivation, alterations in biochemical and histological parameters, and ultrastructural changes in target tissues reflect physiological and morphological disturbances in fish. The novelty of this study is that these parameters can be considered as biomarkers of feeding stress in fish and fish health and can provide important insights for better aquaculture practices.

Cage culture has been proposed as an option to solve the problem of excessive recruitment and stunting in mixed sex Nile tilapia culture. An experiment was set up in a completely randomized design (CRD) for 4 months to assess the growth performance of mixed sex Nile tilapia in monoculture, biculture, and polyculture with African catfish (Clarias gariepinus, Burchell 1822) and African carp (Labeo victorianus, Boulenger 1901) in cages. Treatment 1 (T1) (control) was a 100% monoculture treatment of Nile tilapia, T2 had a 1:1 combination treatment of Nile tilapia and the African catfish, T3 had 1:1 combination treatment of Nile tilapia and African carp, and T4 had a 5:3:2 combination of Nile tilapia, African catfish, and African carp, respectively. The results revealed that there were no significant differences (p > 0.05) in the growth parameters of Nile tilapia when monocultured, bicultured with each of the two species of fish, and when polycultured with both of them. However, there were significant differences in the survival rates (p < 0.05). The final weight (g) achieved were 32.59 ± 8.75, 36.58 ± 7.29, 34.16 ± 7.73, and 32.02 ± 9.00, respectively. The mean weight gain (g) for Nile tilapia monocultured, bicultured with each of them, and when polycultured with both in cages were 25.07 ± 0.62, 29.86 ± 3.04, 25.91 ± 4.98, and 25.05 ± 2.23, respectively. There were significant differences (p < 0.05) in the condition factors of Nile tilapia in the different species combination treatments. Nile tilapia bicultured with African carp had relatively higher growth rates showed isometric growth and a better condition factor than the rest.

The length-weight relationship and condition factor of Clarias gariepinus and Oreochromis niloticus from four study sites (Marmara, Ruwan Jaki, Kogin Mada, and Ruwan Yan akuya sites respectively) in Wudil River, Kano State Nigeria was evaluated over a period of four weeks in December 2010. A total of 120 mature fish samples which were caught during the study period using drag net and traps, were immediately immersed in 10% formalin and transported to laboratory. The growth coefficient (b) obtained of the two fish species ranged from 0.1441 to 0.8058 for Oreochromis niloticus, and from 0.1173 to 0.5457 for Clarias gariepinus. The ‘b’ differed significantly (p &lt; 0.05) from 3, indicating negative allometric growth for all fish species. The condition factor (K) ranged from 0.516 (Clarias gariepinus) from Marmara site, to 1.809 (Oreochromis niloticus) from Kogin Mada sampling site. The condition factors of all fish species sampled fall outside the range recommended as suitable for matured fresh water fish species in the tropics. Key words: length-weight relationship, condition factor, Clarias gariepinus, Oreochromis niloticus, Wudil River

The adverse effect of some environmental contaminants on the endocrine system was investigated using the Risk Analysis Framework. The aim was to ascertain the level of EDCs in fish species and potable water. The research employed ecological examination approach. The samples from the environmental media with serious threat and links to humans and animals exposed to endocrine disruptors were water and fish. Twelve boreholes water samples were disproportionately and purposefully collected, while another twelve water samples were collected from Qua Iboe River one kilometer stretched forth. Also, six species of fresh fish including - Atlantic croaker ( Micropogonias undulates ), Catfish ( Clarias gariepinus ), African red snapper ( Lutjanus agennes ), Tilapia ( Oreochromis niloticus ), Yellowtail ( Seriola lalandi ), and Great barracuda ( Sphyraena barracuda ) were used. Both the water and fish samples were screened for endocrine disrupting substances with gas chromatography linking mass spectroscopy. The analysis (results) detected 8% phenol dichloro-4-nitro-, 1, 3, 5-Triazine, and 3% Triazine 2-chloro-4-, 6-bis-methylthio, octadecenamide in borehole water. Butyl ethyl, hexyl phthalate, indolizine 6%, 4-methyl phenyl, cyclohexane, 3-dione 27%, 2-allylamine methylene 5, 5-hydroxyphenyl 8%, and menazon 17% were discovered in all the species of fish. Phthalate, butyl undecyl esters, 2-ethyl hexyl was 4%, and 7% of isohexyl propyl in Qua Iboe River. The results call for the attention of the regulatory body to put in place measures that will stem the impending disaster this may create in the reproductive capacity of the exposed population.

The ever-growing demand for animal protein to address the rising malnutrition indices of developing nations has led to the flourishing of the fishery and aquaculture industry. But the safety of these processed fish species which come from both wild and cultured sources has been of interest to researches for some time. A comparative assessment of the gastro-intestinal parasites of cultured and wild species of Clarias gariepinus and Oreochromis niloticus was therefore carried out in the Southern part of Nasarawa State. Microscopic examination of the guts of 90 fishes, comprising 60 Clarias gariepinus and 30 Oreochromis niloticus revealed the presence of helminths (cestodes, nematodes and trematodes), algae and some insect larvae. A total of 17 (18.88%) of Clarias gariepinus and 8 (8.88%) of Oreochromis niloticus were infected with gastro-intestinal parasites, giving an overall prevalence of 27.77%. Cultured Clarias gariepinus and Oreochromis niloticus were less infected with parasites than wild species with a statistical significance of P = 0.0034 in this relationship. Also, Clarias gariepinus were found to be more infected with parasites than Oreochromis niloticus. Different species of algae were found in Orechromis niloticus while various stages of insect larvae were found in Clarias gariepinus only; an indication of their feeding habit and the niche they occupy in the aquatic ecosystem. Trichinella specie was found in some of the Clarias gariepinus examined, emphasizing its carnivorous tendencies.

The levels of organochlorine pesticides (OCPs) in water, sediment, Nile Tilapia and African Catfishes were assessed to estimate possible consumer exposures and potential health implications from the Volta Lake, Ghana using gas chromatography equipped with 63Ni electron-capture detector. In agreement with their lipophilic nature, higher levels of OCPs were measured in fish samples than water and sediment samples. Heptachlor was the highest level of OCP measured with concentration of 37.75 ng/g in tilapia gill followed by δ-HCH in tilapia muscle and catfish muscle respectively. All OCP residues in tilapia muscle and catfish muscle did not differ significantly (p<0.05). The highest total OCP load of 66.70 ng/g was measured in tilapia muscle, followed by 63.44 ng/g for tilapia gill. This observation however, contradicts the lipophilic nature of OCPs since the fat content of tilapia gill (14.49%) was five times that of muscle tissues (2.80%). Gill tissues however, may be serving as channels to absorb and distribute OCPs to various fatty tissues in the anatomy and physiology of fish. In water a sample δ-HCH was the highest OCP determined with concentration of 0.669 μg/L. DDT was not detected in both water and sediment samples but was however measured in fish samples. This could be attributed to historical use since DDD and DDE were measured in higher concentrations. From the consumer exposure analysis, the water from the lake is relatively safe for domestic, agricultural and ranching since the acute risk ratio for all detected OCP residues were less than one. The Nile tilapia and African catfishes from this lake are also comparatively safe for human consumption because the estimated dietary intakes from this study are far below the corresponding acceptable dietary intakes for various OCPs. This study therefore shows a declining trend on the environmental burden of OCPs in the middle section of the Volta Lake.