African Catfish Clarias Gariepinus Research Articles

Endohelminth diversity in the invasive Clarias gariepinus (Burchell, 1822) from two freshwater lakes: Naivasha and Ol'Bolossat, Kenya.

Fish parasitology contributes to our understanding of the potential risks posed by diverse groups of parasitic organisms on fish stocks in either wild and culture systems. This study was conducted in May 2023 and aimed at assessing the diversity of endohelminths in the invasive North African catfish Clarias gariepinus (Burchell, 1822) obtained from two freshwater lakes, Naivasha and Ol'Bolossat, in Kenya. Parasitological examination of 66 and 35 fish samples collected from the two lakes respectively was achieved using light and scanning electron microscopy methods. Results revealed endohelminth diversity broadly classified as four digeneans, two nematodes, and one cestode. Seven taxa of endohelminths were found in C. gariepinus samples, but only four of these taxa could be identified up to the species level. Six of the taxa (Diplostomum sp., Tylodelphys mashonense, Plagiorchioidea sp., Paracamallanus cyathopharynx, Contracaecum sp., and Tetracampos ciliotheca) were common in samples from the two lakes. Glossidium pedatum only occurred in samples from Lake Ol'Bolossat. Parasite prevalence ranged from 8.6 (T. mashonense) to 100% (Diplostomum sp., T. ciliotheca, and Contracaecum sp.) and mean intensity from 1.4 (T. mashonense) to 16.9 (Diplostomum sp.). The diversity and richness indices were comparatively higher in fish samples from Lake Ol'Bolossat and attributed to the occurrence of G. pedatum in the Ol'Bolossat. However, parasitic infestation of fish samples from the two lakes depicted close similarity, both in diversity and prevalence. These findings form an important baseline data for further follow-up studies, and they suggest the need for further molecular analyses to fully describe three of the taxa only identified up to the genus level.

Effect of Lead and Chromium on the Toxicity of Glyphosate Herbicides to African Catfish Clarias Gariepinus (Burchell 1822)

There is a growing increase in pollution of the aquatic ecosystems with a wide range of chemicals including herbicides and heavy metals input through anthropogenic activities, leading to disruption of ecological balance. This study used a static toxicity bioassay to examine the interaction between heavy metals (Pb and Cr) and organophosphorus herbicides (analytical grade glyphosate, commercially formulated - Roundup and Forceup) on African catfish (Clarias gariepinus BURCHELL 1822). Lethal concentrations (LC50) for roundup (RU), forceup (FU), analytical grade glyphosate (AGG), chromium (Cr), and lead (Pb) were 17.23 mg/l, 4877 mg/l, 131.12 mg/l, 21.16 mg/l, and 74.82 mg/l respectively. In addition, fish exposed to varying concentration of chromium (5.0 mg/l and 7.5 mg/l) and lead (20 mg/l and 25 mg/l) with glyphosate (RU: 10 mg/l; FU: 4300 mg/l; and AGG: 100 mg/l) for 96 hours were examined for biochemical parameters. Blood plasma examined for liver and kidney profile indices showed that kidney functions’ parameters (protein, albumin, AST-aspartate aminotransferase, ALT-alanine aminotransferase and Bilirubin) and liver functions parameters (urea and creatinine) increased significantly (p<0.05) when glyphosates combined with lead and chromium treated groups compared with the control group. This study therefore, showed that low concentrations of combined toxicants of glyphosates and heavy metals (Cr and Pb) will synergistically induce deleterious effects on the liver and kidney of Clarias gariepinus.

Reproductive and endocrine-disrupting toxicity of pyrogallol in catfish (Clariasgariepinus)

Endocrine disruptors are synthetic or natural chemicals that can agonize/antagonize hormone receptors or can interfere with the production and secretion of hormones, leading to altered tissue histology and physiology. Pyrogallol is a contaminant widely distributed in aquatic environments that presents health risks to both humans and animals. However, the potential for endocrine disruption by pyrogallol, particularly in fish, are lacking. The purpose of this study was to shed light on how pyrogallol may affect hormone signalling, histopathology, and reproductive outcomes in African catfish Clarias gariepinus. To investigate this, African catfish were exposed to one sublethal concentration of pyrogallol at either 0, 1, 5 or 10 mg/L for 15 days. We then assessed the effects of pyrogallol on the thyroid gland as well as the reproductive system by measuring sex hormone, seminal quality, gonadal histopathology, and histochemistry. Thyroid stimulating hormone and thyroxine showed notable decreases in catfish, and triiodothyronine was decreased with 10 mg/L pyrogallol. Unlike luteinizing hormone, follicle-stimulating hormone was significantly reduced in fish following exposure to pyrogallol relative to controls. Testosterone was also decreased in fish following pyrogallol exposure, whereas 17β-estradiol increased in catfish exposed to pyrogallol. Additionally, in response to pyrogallol toxicity, sperm quality indices, including count, spermatocrit, motility, and sperm viability were adversely affected in a concentration-dependent manner. Pyrogallol exposure also induced several changes in the gonad following exposure to 1, 5, or 10 mg/L. Deformed tubular structures, vacuolation, thickening of the basement membrane, hypertrophy of the seminiferous tubules, intense melanomacrophage localization, spermatozoa loss, and necrosis were all observed in the testes. In the ovary, atretic follicles, deteriorated mature oocytes, degenerated yolk globules, and an increase in perinucleolar oocytes were observed in catfish exposed to pyrogallol. These findings suggest that pyrogallol may act as endocrine disrupting substance in aquatic environments. Further research on the mechanisms by which pyrogallol impairs endocrine systems, particularly in fish, is recommended.

Improving reproductive performance and larvae survival by dietary administration of probiotic Bacillus cereus NP5 in female African catfish Clarias gariepinus

Improving reproductive performance and larvae survival by dietary administration of probiotic Bacillus cereus NP5 in female African catfish Clarias gariepinus

Effect of Gum Arabic (Acacia senegal) on Growth Performance, Carcass Quality and Health of Clarias gariepinus Juveniles

The effect of Gum Arabic (GA) on growth, carcass quality, blood parameters, gut morphometry, and organ histology of African catfish Clarias gariepinus was studied. Five isonitrogenous diets with inclusion levels of GA at 0 g/100 g (GA0; control), 5 g/100 g (GA5), 10 g/100 g (GA10), 15 g/100 g (GA15), and 20 g/100 g (GA20) were formulated in a 40% crude protein diet. Juveniles of C. gariepinus with average weight (7.35±0.48 g/fish) were stocked at 13 fish/25 L of water for 12 weeks in a completely randomized design and fed at 3% body weight daily. Growth indices showed GA10 improved the mean weight gain (69.88±8.89 g) and specific growth rate (2.76±0.14 %/day) while at (GA15); (GA20) growth was depressed. Carcass quality revealed dietary levels were superior to control with GA10 significantly different (p < 0.05) amongst treatments in protein and fat content. Hematological profile showed variations; erythrocyte indices compared to control, while plasma chemistry of aspartate aminotransferase, alkaline phosphatase, and alanine aminotransferase showed no difference (p > 0.05). Gut morphometrics varied with no particular pattern. At inclusion above GA5 the gill, liver, and kidney were affected histologically with no changes in the intestines of all treatments. Diet supplemented with gum arabic at 10 g/100 g improved indices of performance of C. gariepinus juveniles in this study.

An Inclusion Effect of Amino-acid (Histidine) in the Carcass Quality and Mineral Profile of African Catfish Clarias Gariepinus (Burchell 1822)

150 fingerlings of African catfish (Clarias gariepinus) with initial mean weight of ±5.1g was stocked in a glass aquaria and were fed to satiation for 156 days. Histidine was used as a supplement to determine the mineral and carcass quality of African Catfish (Clarias gariepinus) fingerlings at varying inclusion levels (0, 0.2%, 0.4%, 0.6% and 0.8%) representing D1 – D5 in a formulated diet of 40% crude protein.
 The carcass proximate and mineral composition were significantly improved by histidine supplementation but, exhibited no definite pattern of inclination while, moisture decreased significantly with increased histidine level up to diet D5. The calcium composition were significant different (P<0.05) with values ranging between 41.0 and 87.6 mg/gDM.

Molecular characterization and antibiotics resistance of Aeromonas species isolated from farmed African catfish Clarias gariepinus Burchell, 1822

BackgroundAeromonas species are one of the most important etiologies of diseases in fish farms, leading to clinical manifestation and mortality and are associated with public health risks. This study aimed to investigate the prevalence, phenotypic and molecular characteristics of Aeromonas species isolated from farmed Clarias gariepinus using 16 S rRNA sequencing. Additionally, their antibiogram and multiple antibiotic resistance index were determined using a disc diffusion test.ResultsA total of 230 Aeromonas strains were isolated from Clarias gariepinus with 40.9% obtained from diseased fish, and 25% isolated from apparently healthy ones. Five different species including Aeromonas caviae, Aeromonas veronii, Aeromonas hydrophila, Aeromonas dhakensis and Aeromonas enteropelogenes were fully identified and genetically characterized. Based on the available literature, this is the first report of Aeromonas enteropelogenes from the study area. The phylogenetic analysis showed genetic heterogeneity and distance within the species and the reference strains. The multiple resistant Aeromonas species were susceptible to ciprofloxacin, gentamycin, and florfenicol. The Aeromonas species’ multiple antibiotic resistance index values varied between 0.20 and 0.80 and were isolated from the farms where antibiotics were intensively used.ConclusionsThe diversity of multidrug-resistant Aeromonas species isolated from fish farms is a major threat to fish production giving us more understanding of epidemiology and the multidrug Aeromonas species with a MAR index of greater than 0.2 were isolated from farms where antibiotic use was widespread. As a result, a considerably increased danger of multiple antibiotic resistance spreading to the fish culture environment may impact aquaculture production. Hence there is a need for appropriate and monitored drug usage.

Efficacy of Tannin Extract from Cape Gooseberry Root Physalis peruviana L. as Egg De-Adhesion Agent during Artificial Propagation of African Catfish Clarias gariepinus Burchell

The study assessed the best immersion period and concentrations of the Cape gooseberry root Physalis peruviana that can efficiently remove egg adhesiveness of Clarias gariepinus. One male and one female C. gariepinus brood stock weighing 1.0 kg and 1.3 kg respectively, were used for the experiment. Three different concentrations (0.5%, 1%, and 2%) of tannin extract from Cape gooseberry root were used. Tannic acid (0.75g) diluted in 1 litre of water was used as reference de-adhesion agent, while water was used as control. The fish eggs were rinsed with the solutions at different durations of 0.5, 1 and 2 minutes. Each concentration and rinsing time was recorded in triplicates. Data generated were subjected to Univariate Analysis of Variance Test, and third order Polynomial regression analysis was then used to determine the best concentration and immersion period that neutralizes adhesiveness in eggs of C. gariepinus. Results of the study showed that there were no significant differences (p≤0.05) in the non-adhesive eggs and hatching of eggs immersed in tannin extract from Cape gooseberry root and Tannic acid solution but significantly different from the control. Therefore, this study showed that tannin extract from Cape gooseberry root at 1% concentration and 1 minute immersion period is more efficient for egg adhesion and increase hatching in C. gariepinus.

Preservative Effect of Vernonia amygdalina Extract on Microbial Activity, Proximate Composition and Sensory Evaluation of Smoked-dried African Catfish Clarias gariepinus (Burchell, 1822)

The effect of Vernonia amygdalina extract on microbial activity, proximate composition and sensory evaluation of smoked-dried Clarias gariepinus stored at 32.0±2°C was determined over the period of 21 days. The experimental treatments were the control, 0.5%, 1%, 1.5% (w/v) Vernonia amygdalina extract solutions. 52 fish of average mean weight of 30.98±1.32g were degutted, washed and randomly assigned to the treatments and soaked in the extract solutions for 30 minutes and later smoked-dried for 12 hours. Six bacterial species namely, Bacillus subtilis, Corynebacteria sp, Proteus mirabilis, Streptococcus faecalis, Staphylococcus albus and Staphylococcus aureus were observed in the study. There was no increase in the microbial loads in all the treatments except in the control which increased from 27×103 to 40×103 cfu. Highest crude protein content (48.08±0.82%) was recorded in the control while the least value (39.67±0.04%) was obtained in the fish treated with 0.5% concentration of the extract. There was no significant difference (P>0.05) in the sensory evaluation among all the treatments and the control. This study reveals that V. amygdalina extract can be used as preservative in protecting smoked-dried C. gariepinus from bacterial spoilage, thus limiting economic loss and possible health risk to consumers.

Fatty Acid Profile, Atherogenic and Thrombogenic Indices, and Meat Quality as the Effect of Feed Additive in African Catfish Clarias gariepinus (Burchell, 1822)

Humic substances (HS) are often used as feesd additives in livestock feeding. The long-term effects of different concentrations of HS additives in aquafeed on growth and production performance, antioxidant status, stress resistance, gut microbiome, overall health condition, final product yield, sensory properties of fresh and cooked meat, and composition of fatty acids of market size in African catfish (Clarias gariepinus) originating from aquaculture were compared in this study. C. gariepinus were exposed to dietary inclusions of HS (0, 1, and 3, and 6% w/w) in a long-term experiment (six months in total) until fish reached market size. The growth parameters, condition factor, and selected somatic indices did not differ (p > 0.05) between the tested groups (HS0–HS6). Biochemical parameters were not different between the tested HS groups by the end of experiment, and only glucose (GLC) levels significantly increased (p < 0.05) with increasing concentrations of HS fed as an additive. The levels of cortisol (COR) and GLC did not differ between the tested groups (p > 0.05) after the stress challenge, but the results of GLC levels before and after the stress challenge showed an increasing tendency with increasing levels of HS addition in the diet. The levels of COR were slightly lower in groups HS3 and HS6 than in HS1 and the control group. In the case of protein and fat contents, differences between groups (HS0–HS6) were statistically insignificant. Significant differences were found, however, in water and ash content. In some cases, statistically significant differences were found in fatty acid profiles and in nutritional indices assessing fatty acids between samples. Sensory characteristics of fresh fillets did not differ between the tested groups HS0–HS6. The total content of polyphenols increased depending on the addition of humates. The main gut microbiota of samples analyzed (HS0–HS3 group) comprised the following three genera: Ralstonia, Pseudomonas and Cetobacterium; other genera were present in all samples at a low relative abundance: Staphylococcus, Bradyrhizobium, Bacillus, and Anaerobacillus. The relative abundance of Pseudomonas decreased while the presence of Cetobacterium increased in samples fed with 3% of HS. The results of our study yielded a comprehensive set of experimental results about African catfish fed with HS as additives. Although a significant effect of HS on overall performance of C. gariepinus was not proven, a positive effect on antioxidant status was seen as well as a decrease in gut microorganisms that can be present as pathogenic contaminants in aquatic environments.

Abnormalities in behavioral responses and hematological parameters of African catfish Clarias gariepinus juveniles exposed to acute and sub-chronic effects of mancozeb

Abnormalities in behavioral responses and hematological parameters of African catfish Clarias gariepinus juveniles exposed to acute and sub-chronic effects of mancozeb

Reproductive biology and condition factor of the African catfish, Clarias gariepinus (Burchell 1822) in Lake Koka, Ethiopia

The study was conducted to investigate the breeding season, sex ratio, size at maturation, fecundity and condition factor of African catfish Clarias gariepinus in Lake Koka. A total of 754 fish specimens were collected from October 2020 to August 2021. Total length and weight were measured and sexes were identified and gonad maturity levels were recorded. The sex ratio of African catfish in different size classes was similar to that of a hypothetical 1:1 ratio. The length at first maturity (L50) was 51.8 cm in total length. The mean Fulton’s condition factor of female African catfish ranged from 0.65 ± 0.05 – 0.71 ± 0.14, while the males ranged from 0.62 ± 0.04 – 0.7 ± 0.11. The Fulton’s condition factor was significantly higher in August for females than in the rest of the sampling months. The highest ripe gonads were recorded in the rainy season and the lowest was in the dry season, with the percentage of ripe gonads being 27.5%, while the males showed similarly extended maturity patterns among seasons. Fisheries management for African catfish should therefore take into account the estimated L50 value and the main breeding season to sustain the fishery and benefits the fishermen.

DNA barcoding of five economically important freshwater fish species from the Nile River, Sudan

The study was conducted to barcode five freshwater fish species obtained from Nile River tributaries (the Atbara River and the Blue Nile), in March 2019, using analysis of partial CO1 gene sequences. Fish samples were identified morphologically as Nile perch Lates niloticus, Nile labeo Labeo vulgaris, North African catfish Clarias gariepinus, Cornish jack Mormyrops anguilloides and bebe mormyrid Hyperopisus bebe. Following DNA extraction, universal primers were used for amplification of the CO1 barcode region. The PCR products were sequenced and used for molecular identification. Each sequence was matched to corresponding GenBank sequences using the BLAST technique. Sequences of all specimens were aligned along with the GenBank published sequences and polymorphic sites were identified. The analysed sequences were uploaded to GenBank under the accession numbers OL804282– OL804286. The analysed partial CO1 barcode gene showed a readable length of ∼548–669 base pairs. Sequence comparison of CO1 gene sequences with sequences published in GenBank revealed 99.27–100% identities at the species level. Therefore, the CO1 barcodes accurately identified all the studied freshwater fishes. This is the first molecular DNA barcode characterisation of freshwater fish species found in Sudan. The fish CO1 gene sequences revealed in this study will serve as barcode references for future characterisations of Nile River fishes.

Community structure, seasonal dynamics, and impact of some biological parameters of the African catfish Clarias gariepinus on the infection level of the helminth parasites.

Fish parasitic diseases impose a major economic concern on aquaculture. Identified parasites of Clarias gariepinus include one monogenean, Macrogyrodactylus clarii (gills), three digeneans Orientocreadium batrachoides, Eumasenia bangweulensis and Sanguinicola sp. (intestine), two cestodes Tetracampose ciliotheca and Monobothrioides chalmersius (intestine) and two nematodes Paracamallanus cyathopharynx and Procamallanus pseudolaeviconchus (intestine and stomach). Most nematodes, digeneans and cestodes occurred in all months of the study period. However, M. clarii and Sanguinicola sp. disappeared for 6 and 8months of the year, respectively. The digenean group was the most dominant followed by the cestode and nematode groups, respectively. The nematodes attained the highest infection rate over the digeneans and cestodes while the monogenean M. clarii recorded the lowest infection rate. The infection level of examined parasites varied seasonally, but no overall significant pattern was detected. E. bangweulensis showed a highly significant difference for all parameters seasonally. A higher prevalence was obvious in males than females for most parasites, and the opposite for the mean intensity except for P. pseudolaeviconchus which was significantly different between females and males in the mean abundance. There were variations in the relationship between the host condition factor and helminth parasite infection levels. O. batrachoides, E. bangweulensis and P. cyathopharynx recorded the highest infection level in class II. The mean prevalence was highly significantly different between host classes for T. ciliotheca, M. chalmersius and P. pseudolaeviconchus.

Scanning Electron Microscopy and First Molecular Data of Two Species of Lamproglena (Copepoda: Lernaeidae) from Labeo victorianus (Cyprinidae) and Clarias gariepinus (Clariidae) in Kenya.

A parasitological study carried out in May 2022 and March 2023 in the Nyando River of Lake Victoria Basin, Kenya, disclosed two parasitic lernaeid copepods: Lamproglena cleopatra Humes, 1957, from the gills of a cyprinid, the Ningu Labeo victorianus Boulenger, 1901, endemic to the Lake Victoria drainage system, and Lamproglena clariae Fryer, 1957, from a clariid, the North African catfish Clarias gariepinus (Burchell, 1822). The copepods were studied and supplementary taxonomic information was presented using scanning electron micrographs and genetic data. Scanning electron microscopy (SEM) provided information on the morphology of L. cleopatra's antennae, oral region, thoracic legs (2-5), and furcal rami not previously reported. Analyses of the partial fragments of 18S and 28S rDNA and cytochrome c oxidase subunit 1 (cox1) of the two parasites showed them to be distinct from all other Lamproglena taxa retrieved from GenBank. This study presents new taxonomic information on morphology using SEM and provides the first ribosomal (18S and 28S rDNA) and mitochondrial (mtDNA) data for these two parasite species. The cox1 data provided are the first for all 38 nominal species of Lamproglena. Notably, the study also provides a new host record for L. cleopatra and extends the geographical information of this species to Kenya.

Melaleuca cajuputi leaf extract accelerates wound healing in African catfish, Clarias gariepinus

African catfish Clarias gariepinus is a scale-less fish prone to injury from high stocking under captive condition. Untreated wounds are susceptible to pathogenic infections that can cause biological and economic losses. This study evaluated the potential of Melaleuca cajuputi leaf extract (MCLE) for wound treatment in artificially injured C. gariepinus. Methanol extracts of M. cajuputi were freeze-dried and applied as treatment solutions as follows; 0.0 mg/L, 12.7 mg/L, 25.4 mg/L, and 38.1 mg/L. Tetracycline was used as a positive control group. The fish were artificially injured (i.e., laceration of 1 cm long, 0.4 cm depth) on both lateral sides and allowed to swim in the treatment solutions for 30 days. Wound healing progress, histological changes, hematological and biochemical parameters are herein reported. Results revealed that MCLE treatments caused faster epidermal cell migration, epidermal covering, and cell proliferation as early as 1 h after the artificial injury was inflicted compared to the control. At 3 h, the MCLE treatment at 12.7 and 25.4 mg/L caused the wounds to be closed and initiated the formation of the basement membrane; where these conditions were found only after 6 h with the tetracycline and control treatments. Meanwhile, the vascularization was found to occur after about 6 h in the 12.7 and 25.4 mg/L MCLE treated fish, whereas the process was delayed until 12 h in untreated fish. Our finding shows that treatment of fish wounds for 30 days with MCLE did not affect the health status of the fish as no significant changes (p > 0.05) were observed between the MCLE-treated and control groups for most parameters. It was concluded that the treatment of injured C. gariepinus can be done using MCLE concentration between 12.7 and 25.4 mg/L to accelerate healing.

Carica papaya extract: a new leaf in treating dengue?

Carica papaya extract: a new leaf in treating dengue?

Comparison on inclusion of potent and expired Astaxanthin in the diet of ANH7 African catfish Clarias gariepinus fingerlings for skin and flesh pigmentation

Background and Objective: The aim of this study seeks to Compare the effects of Inclusion levels of Potent and Expired Astaxanthin in the Diet of African catfish Clarias gariepinus Fingerlings for Skin and Flesh Pigmentation. Materials and Methods: A 120 fingerlings Clarias gariepinus was used which was procured from a reputable farm in Jos, Plateau State, Nigeria. They were then taken to the Hydrobiology and Fisheries Laboratory of the University of Jos, Nigeria and allowed to acclimatize for three weeks before the feeding started. The experiment involved the use of 19 fibre glass tanks having average capacity of 95 litres. It was run under the flow-through system at 100 ml/min in order to avoid pollution. Results: After a feeding period of eight weeks, increasing the level of astaxanthin (potent and expired) in the feed of Clarias gariepinus fingerlings from 100 (T1) to 150 (T2) to 200g/kg (T3), the concentration of carotene in the skin increased significantly (p < 0.05) between the treatments except for the control. The effect of pigmentation was given in the skin and flesh of Clarias gariepinus fingerlings fed both potent and expired astaxanthin, except that, the potent astaxanthin gave higher effect of pigmentation on both skin and flesh than the expired astaxanthin. Conclusion: It was however, found that, the concentration of astaxanthin in the skin was higher than that in the flesh under every treatment for both potent and expired astaxanthin.

Effects of Temperature Variation on Behaviour and Growth Performance of African Catfish Clarias gariepinus

The effect of temperature variation on the behaviour and growth performance of Clarias gariepinus was studied. Temperature has both direct and indirect influence on fisheries and aquaculture. This study was set to evaluate how changes in temperature of the aquatic environment influence the behaviour and growth of Clarias gariepinus as one of the best aquaculture candidates especially in central and western Africa. The fish were subjected to different temperature conditions over a period of eight (8) weeks. Changes in fish behaviour were determined by careful observation of feeding behaviour as well as swimming patterns. Changes in the growth of fish were determined by measuring the weight of the fish and the standard length of the fish accordingly. The outcome of the current study reveals that temperature significantly affects the behaviour and growth performance of Clarias gariepinus. The effect is more significant in the weight than the length of the fish. Temperature values between 20-27 ℃ are more suitable for proper growth and well-being of Clarias gariepinus, any further increase in temperature above 27 ℃ causes a decline in the growth that fish species.

Glycogen in retinal horizontal cells of the African mud catfish Clarias gariepinus (Burchell, 1822) and its physiological significance

This paper reports on glycogen store in the retinal horizontal cells (HC) of the African mud catfish Clarias gariepinus, as seen by histochemical reaction with periodic acid Schiff (PAS) and transmission electron microscopy in light- as well as dark-adapted state. Glycogen is abundant in the large somata and less in their axons, characterised ultrastructurally by many microtubules and extensive gap junctions interconnecting them. There was no apparent difference in glycogen content in HC somata between light- and dark adaptation, but the axons clearly showed absence of glycogen in dark condition. The HC somata (presynaptic) make synapses with dendrites in the outer plexiform layer. Müller cell inner processes, which contain more densely packed glycogen, invest the HC. Other cells of the inner nuclear layer do not show any appreciable content of glycogen. Rods, but not cones, contain abundant glycogen in their inner segments and synaptic terminals. It is likely that glycogen is used as energy substrate in hypoxia for this species that dwell muddy aquatic environment with low oxygen content. They appear to have high energy demand, and a high glycogen content in HC could act as a ready source to fulfil physiological processes, like microtubule-based transport of cargo from the large somata to axons and the maintenance of electrical activities across the gap junctions between the axonal processes. It is also likely that they can supplement glucose to the neighbouring inner nuclear layer neurons, which are clearly devoid of glycogen.