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This study was conducted to contribute to a better understanding of the phenotypic diversity of natural populations of Clarias jaensis in Cameroon, with the objective to harness the exploitation and conservation of this native catfish. A total of 269 native catfish (Clarias jaensis), including 139 males and 130 females, were sampled on 6 sites in Cameroon. One (1) phaneroptic observation, seventeen (17) biometric traits and four (4) meristic traits were evaluated. The main results showed that there are three colour patterns (brown, black and marbled) on the dorsal region and flanks in Clarias jaensis, with a predominance of brown (81.04%) and black (11.52%) patterns. The effect of sex on total weight (TW), snout length (SnL), prepelvic length (PPvL), total length (TL), standard length (SL), body depth (BD) and caudal peduncle depth (CPD) was significant (p<0.05). In general, biometric traits were significant (p<0.05) and positively correlated with total weight. The number of soft fin rays in dorsal fin (D) and anal fin rays (A) were negatively and weakly correlated with total weight (r=-0.02 and r=-0.04 respectively), while, the number of soft fin rays in pectoral fin was negatively and weakly correlated with total weight (r=0.13). The Principal Component Analysis (PCA) performed on all the biometric and meristic traits shows that the first two axes alone account for more than 50% of the total inertia. Hierarchical Ascending Classification (HAC) highlighted the existence of 3 morphotypes. The observed biodiversity suggests that the Clarias jaensis catfish is a natural genetic resource with the necessary variability to be exploited, though there is a need to develop population and habitats monitoring plan. [ABSTRACT FROM AUTHOR]

The skeletal system is primarily driven by the skeletal muscles to produce kinematic movements. The study evaluates the histological and morphometric properties of skeletal muscle in Clarias gariepenus (Cl. gariepinus), Bufo bufo (B. bufo), Agama agama (A. agama), Columba livia domestica (C. domestica) and Rattus rattus (R. rattus). The study was carried in order to relate the similarities and differences of skeletal muscles in these species with evolutionary trend. The epaxial muscle of Cl. Gariepinus, the biceps femoris muscle of B. bufo, R. rattus, puboischiotibialis of A. agama, and pectoral muscle from C. domestica were removed and assessed grossly for physical appearance then processed for histological analysis. The diameters of the muscle fibers were measured and one-way analysis of variance was used to compare the differences. The muscles of Cl. gariepinus, B. bufo and A. agama appeared whitish with scanty fusiform nucleus and large intermuscular space. However, the muscles of C. domestica and R. rattus appeared red with distinct round nucleus and small intermuscular space. No significant difference (P>0.05) was observed in the muscle diameter of Cl. gariepinus (8.86±0.13µm) compared to B. bufo (8.25±0.27µm). The muscle diameter of A. agama (10.18±0.25µm) was significantly higher (P<0.05) relative to Cl. gariepinus (8.86±0.13µm), B. bufo (8.25±0.27µm), C. domestica (3.38±0.13µm) and R. rattus (4.66±0.15µm). Conclusively, non-tetrapod vertebrates (Cl. gariepinus, B. bufo, and A. agama) have simple, white-colored skeletal muscle with few flat-shaped nuclei and large fiber diameters while higher vertebrates (C. domestica and R. rattus) have complex, red-colored skeletal muscle with numerous oval-shaped nucleus and small fiber diameter. [ABSTRACT FROM AUTHOR]

A comparative study on the relationship between condition factors and parasite density of Heterobranchus isopterus and Clarias gariepinus was conducted during the wet and dry seasons. Specimens were collected from the Bagoué River from August 2020 to July 2021. Two hundred eighty-four specimens of H. isopterus and 272 specimens of C. gariepinus were collected from all stations during both seasons. The standard length and weight of the fish were recorded and the condition factor was calculated for each individual. The gills were examined under a binocular loupe and the monogeneans were collected. Parasite counts showed that for both host species, the total number of parasites was higher in the dry season than in the wet season (p < 0.05). The correlation coefficient was determined to investigate the relationship between the condition factor and the total number of parasites. A significant positive correlation was observed between the condition factor and the number of parasites in both host species during the wet season. A negative correlation was observed in both hosts during the dry season. The information from this study could be taken into consideration in the sanitary management of the fish farming industry. The dry season could be considered as the season with favorable conditions for the development of most parasite species. [ABSTRACT FROM AUTHOR]

The present study described the most recent findings concerning the abundance and distribution of plastic in water, sediment, and fauna in the Nile River of Upper Egypt as an interesting research point. The findings revealed that plastics were abundant in the water, sediments, fish, and crayfish throughout the sites. The Nagaa Hammadi site has the highest abundance of meso- and macroplastics in its water and sediment. African catfish had the highest abundance of meso- and macroplastics compared to the other species, while Nile tilapia had no meso- or macroplastics in its alimentary canal or gills in all sites. The Edfu site has the highest abundance of mesoplastics in the alimentary canals of African catfish, while the Nagaa Hammadi site has the highest abundance of mesoplastics in the gills, and macroplastics appeared only in the alimentary canal of African catfish from the El-wasta site. Only mesoplastics were found in the crayfish's alimentary canal, with the Nagaa Hammadi site having the highest abundance. No macroplastics were detected in the crayfish's gills or alimentary canal. Additionally, this work lets us understand how plastics behave in freshwater environments, and it is a step toward decision-makers taking appropriate measures to reduce their risk. [ABSTRACT FROM AUTHOR]

Understanding the relationship between fish parental age and offspring performance over their life cycle is crucial for aquaculturists. This study investigates the effect of parental age for both 1- and 2-year-old fish on the growth and survival rates of their larval to grow-out stages for two wild and domesticated strains of bighead catfish (Clarias macrocephalus). Fish were sampled from the Vietnamese Mekong Delta where wild adult fish were collected from a conservation area in Ca Mau Province and domesticated fish were taken from a hatchery in Can Tho. Four offspring treatments of 1- and 2-year-old broodstock strains were reared for 3 successive periods: 40 days for fingerling rearing in static tanks with water exchange, 60 days for juveniles, and 90 days for grow-out in recirculating systems. The final weight of fish at 190 days varied from 96.7 to 144.7 g. The growth of offspring was not affected by parental age (P > 0.05), over the 3 rearing periods. However, the domesticated fish strain showed significantly better growth rates than the wild fish strain (P < 0.05). Feed conversion ratios were comparable across fish treatments. Survival rates did not differ at the fingerling (21.8%-36.4%) and juvenile (69.0%-73.3%) stages. However, significant differences were found at the grow-out stage (69.3%-84.0%), with offspring from 2-year-old parents of both strains having greater survival rates. Overall, 1- and 2-year-old fish appear to be suitable for bighead catfish breeders. [ABSTRACT FROM AUTHOR]

Aquaculture has a land potential of 17.92 million ha consisting of 2.83 million ha of freshwater aquaculture potential, 2.96 million ha of brackish water aquaculture and 12.12 million ha of marine aquaculture. One of the freshwater species that has the potential to be cultivated is catfish (C. gariepinus). But now, as a result of the decline in the quality of the freshwater environment, catfish are prone to contamination by plastic waste. If microplastic particles have accumulated in large numbers in the fish's body, they can clog the fish's digestive tract and affect the growth of catfish which will affect the results of aquaculture production. The purpose of this study was to determine the survival rate or survival rate of catfish exposed to microplastics. The research design used in this study was a Completely Randomized Design (CRD) with 1 control variable, namely no mixing of microplastics in commercial feeds and 3 different doses of microplastics, namely A (5%), B (10%), C (15%) mixed with commercial feed, where each treatment was repeated 3 times. The results of the one-way ANOVA analysis showed that the treatment of exposure to microplastics with different doses did not have a significant effect (P<0.05) on the survival rate and length growth of catfish. The survival rate ranges from 65-100%. Survival values that were not significantly different could indicate that there was competition for space and dominance of larger fish in the aquarium which affected fish growth, feed utilization and fish survival. Meanwhile, the length growth value ranged from 21-28cm. The length growth value which was not significantly different could indicate that the dose of microplastic used in the study did not result in muscle and bone cell division which was the cause of the increase in the body length of fish. [ABSTRACT FROM AUTHOR]

Clarias sp. is one of the major genera of freshwater catfish and also a common commodity in tropical aquaculture. Excessive light intensity is expected to be responded to by fish as environmental stressors. Fish that experience stress will increase the secretion of catecholamine, cortisol, blood glucose levels, and p38 MAPKs in catfish. The different intensities of light will affect the fish's physiological processes. The purpose of this study was to analyze the physiological responses (Level of blood glucose, primary stress hormone (Cortisol) and p38 MAPKs) of catfish Clarias sp. which were incubated at different lights intensity of catfish. 300 fish were collected from Kepanjen Regency, East Java. Blood and meat sampling are carried out to test the profile of glucose, cortisol, and p38 MAPKs. The experimental research at this stage was carried out by transferring the catfish from Kepanjen to an experimental aquarium (50 x 30 x 30 cm) that set the different light intensities (0 lux (control), 400 lux, 800 lux, and 1200 lux). Each experimental aquarium is filled with 15 catfish and will be kept for 21 days. Quantification of the parameter using ELISA method. The study result showed the highest peak of primary stress hormone (cortisol) levels is 34±1,50 ng/mL, blood glucose levels are 120±3,4 mg/dL, and p38 MAPK is 97±1,1 %. All of it was achieved in the treatment of 1200 lux in the 2nd week. [ABSTRACT FROM AUTHOR]

The unsustainable use of fish meals as protein and lipid ingredients in aquafeed has driven the search for an alternative. Black soldier fly (BSF) (Hermetia illucens) larvae have been widely studied for substitution purposes. This study aims at investigating the effect of solid fermentation of pelleted diets containing BSF larvae meal (BSFLM) on the growth performance of catfish Clarias sp. Four feed pellets were formulated: F1 (non-fermented, 60% BSFLM), F2 (fermented, 60% BSFLM), F3 (non-fermented, 50% BSFLM), and F4 (fermented, 50% BSFLM). These formulated diets and commercial feed pellets (positive control) were separately fed to the catfishes in 5 aquaria (10 fishes per aquaria in triplicate). Results showed that the fermentation increased the protein level by 10-11%, but kept the crude lipid concentrations unchanged. Specific growth rate (SGR) and weight gain (WG) profiles for fermented feeds F2 and F4 were higher than the non-fermented feeds F1 and F3, respectively. F4 gave the best feed conversion ratio (FCR) of 1.78, which was 15-25% more efficient than F1, F2, and F3. Compared to the commercial feed, the 4 formulated feeds underperformed by around 50% in all of the growth parameters except survival rates (SR) which were not significantly different (93-100%). [ABSTRACT FROM AUTHOR]

This study investigated the relationships among parental body weight, egg size and number, and offspring performance at the larval, juvenile and grow‐out stages of bighead catfish (Clarias macrocephalus) in Mekong domesticated (Can Tho; CT) and wild (Ca Mau; CM) strains. One‐year‐old broodstock from each strain were separated into two size groups, with those in the large (L) group having, on average, approximately double the body weight of those in the small (S) group. Both strains exhibited a strong linear increase in absolute fecundity (slope = 58.8, p < 0.01 for CT and slope = 52.3, p < 0.01 for CM) and a slight increase in egg diameter associated with increasing female body weight (slope = 0.0002, p = 0.03 for CT and slope = 0.0003, p = 0.06 for CM). However, there were no linear correlations between female body weight and yolk‐sac volume or larval body length at hatching (p > 0.05). Despite similar fecundities, the CM wild strain had larger eggs and more favourable larval properties than the CT domesticated strain (p < 0.01). However, these advantages did not result in better growth and survival of CM offspring at any stage. The CT strain showed improved growth in offspring with parents in the L group compared to those with parents in the S group across the three stages (35.7%, 50.0% and 43.9% respectively), while there was no significant increase in growth in the CM wild strain (p > 0.05). Parental body weight and strain had no effects on survival and feed conversion ratios (FCRs), with the exception that juveniles of the CM S group had the lowest SR (38.8 ± 6.0%) and FCR (1.09 ± 0.08) due to disease infection. The CT L group grew fastest and consumed the highest amount of food with similar feed efficiency to the other groups in juvenile and grow‐out stages (p < 0.05). These results indicated that the pertinence of 'the bigger the better' paradigm varied between growth stages in the two bighead catfish strains. [ABSTRACT FROM AUTHOR]

Rice bran is being fermented using Aspergillus niger in order to increase its usage as a raw material for the catfish diet. This research aims to evaluate the potentials of rice bran fermented with A. niger to replace soybean meal in catfish Clarias sp diet. There were two research stages, first the fermentation test of A. niger on rice bran that used a completely randomized factorial design consisting of 2 factors, namely the dose of A. niger (0, 0.5, 1, 1.5, and 2 g/100 g) and incubation time (0, 24 and 48 hours). Secondly, the substitution test of soybean meal with fermented rice bran on five different of substitution levels (0, 15, 20, 35, and 40%) in the catfish diet. The results showed that the fermentation of A. niger of 2 % with an incubation period of 24 hours in rice bran resulted in the smallest crude fiber and fraction content, and increased protein and amino acid including serine, threonine, alanine, methionine, isoleucine, and lysine. The specific growth rate in the substitution treatment of 0-20% was significantly (P<0.05) higher than that of 35-40%. There was also no difference (P>0.05) in the growth performance of catfish in the 0 to 20% substitution treatment. Also, replacing soybean meal with fermented rice bran up to 20% did not have a negative effect on the growth performance of catfish. It was concluded that fermented rice bran could be used as raw material for catfish. [ABSTRACT FROM AUTHOR]

Abstract Background Aquaponics are food production systems advocated for food security and health. Their sustainability from a nutritional and plant health perspective is, however, a significant challenge. Recirculated aquaculture systems (RAS) form a major part of aquaponic systems, but knowledge about their microbial potential to benefit plant growth and plant health is limited. The current study tested if the diversity and function of microbial communities in two commercial RAS were specific to the fish species used (Tilapia or Clarias) and sampling site (fish tanks and wastewaters), and whether they confer benefits to plants and have in vitro antagonistic potential towards plant pathogens. Results Microbial diversity and composition was found to be dependent on fish species and sample site. The Tilapia RAS hosted higher bacterial diversity than the Clarias RAS; but the later hosted higher fungal diversity. Both Tilapia and Clarias RAS hosted bacterial and fungal communities that promoted plant growth, inhibited plant pathogens and encouraged biodegradation. The production of extracellular enzymes, related to nutrient availability and pathogen control, by bacterial strains isolated from the Tilapia and Clarias systems, makes them a promising tool in aquaponics and in their system design. Conclusions This study explored the microbial diversity and potential of the commercial RAS with either Tilapia or Clarias as a tool to benefit the aquaponic system with respect to plant growth promotion and control of plant diseases.

The record is confirmed of a "Clariobranchus" hybrid Clarias gariepinus × Heterobranchus sp. specimen in the River Danube in Croatia. Clarias gariepinus was introduced to Europe for farming and research purposes. Because of their faster growth and short time to achieve market size, "Clariobranchus" hybrids have gained attention in European aquaculture. To date, no record has been found in the literature of "Clariobranchus" hybrid escapees in inland waters of Europe. The present finding suggests that the "Clariobranchus" hybrid escaped from an unprotected aquaculture system or open pond farm. The threat of establishment of a population of this hybrid in suitable environments, such as thermal ponds, cannot be ruled out. [ABSTRACT FROM AUTHOR]

We studied the mechanism of the effects of 17a-methyltestosterone (MT) on previously reported enhanced growth and maturation of the Asian catfish Clarias macrocephalus. A total of 18 pubertal male (3 fish·tank-1) catfish (ABW=125.97 g) were stocked into six experimental circular tanks and fed with a basal diet (control) or a basal diet containing 60 mg MT kg-1 diet for 90 days. At the termination of the experiment, livers were excised, and total RNA was extracted, evaluated, and reverse transcribed to cDNA. Six libraries of cDNA (3 for the control and 3 for the MT-treated group) were subjected to bioinformatics. Differentially expressed genes (DEGs) were identified using similarity scores of the de novo assembled transcript with those in the seven public databases. There were 141 up- and 72 down-regulated DEGs, mostly belonging to uncharacterized/not yet identified proteins. Thus, DEGs in the top enriched KEGG pathways were used to characterize the effects of MT. Upregulated DEGs included tyrosine hydroxylase (TH), Cytoplasmic Polyadenylation Element Binding (CPEB), Fas-associated death domain (FADD), Major Histocompatibility Complex class 1 (MHC-1), other immune-related genes, among others. Down-regulated DEGs included Cytochrome P450 family one subfamily A member 1 (CYP1A1), Alternative oxidase (AOX), UDPglycosyltransferase (UGT), Acyl-CoA Synthase Bubblegum Family Member 1 (ACSBG), Stearoyl-CoA Desaturase (SCD), among others. In conclusion, MT-treated male Clarias macrocephalus exhibited up-regulation of pathways protecting cellular conditions like cell proliferation, survival, development and homeostasis processes, for development and homeostasis processes. MT also affected changes in bile acid production and the inhibition of the production/conversion of testosterone. MT resulted in the downregulation of a serotonergic system that possibly affected gonadal development, inhibition of the retinoid enzyme that would otherwise diminish the full effects of MT or its metabolite, and inhibition of the formation of estrogen, leading to down-regulation of several estrogen-related KEGG pathways. The results provide valuable information about the key genes for use as biomarkers of maturation and reproduction for the Asian catfish and contribute to our understanding of the molecular mechanisms and regulative pathways behind these two processes in fish. [ABSTRACT FROM AUTHOR]

Catfish are important organisms used extensively in aquaculture. For this review, we are focusing on specific species of catfish in the genus Clarias, primarily Clarias batrachus, C. gariepinus, and C. macrocephalus, because of their widespread use in aquaculture and the considerable amount of information that has been amassed on different aspects of their biology. This review summarizes information available on topics ranging from the taxonomy and geographic distribution of these catfish to work done on them at the genetic, molecular biological and genomic levels. This information may be useful in future efforts to grow and expand their use in aquaculture. [ABSTRACT FROM AUTHOR]

Clarias macrocephalus has been extirpated in most regions in the Philippines and as a preliminary study towards its reintroduction, we aimed at enhancing the growth and reproductive performance of the broodstock. Several studies have identified thiamine deficiency as a factor in the extirpation of some important fish species in the wild. The present study aimed to determine the effects of elevated dietary carbohydrates and benfotiamine, a more bioavailable analog of thiamine (vitamin B1). Three diets were used, namely, a commercial diet specific for catfish was used as the control diet (Com), a high carbohydrate (HC) diet, and a benfotiamine-supplemented HC diet (HCB). Results show that survival of the subadult catfish in captivity for 10 weeks was remarkably high, exhibiting an average of 99% for all three treatments (P>0.05). HCB diet resulted in significantly higher final average body weight (FABW), weight gain (WG), specific growth rate (SGR), and significantly best food conversion ratio (FCR) (P<0.05) than the values for both Com and HC groups (P>0.05). For the reproductive performance, female Asian catfish fed the HCB diet exhibited significantly heavier ovary and liver (P<0.05) than those female catfish fed either the Com or HC diet (P>0.05). GSI of the female catfish and fecundity were significantly higher in the HCB group (P<0.05) than in the Com or HC group (P>0.05). In the male catfish, testes were significantly heavier in the HCB group (P<0.05) than in the Com or HC diet (P>0.05). HSI, male LW, and LL were significantly higher in the HC and HCB groups (P>0.05) than in the Com group (P<0.05). GSI values of the male catfish were significantly highest in the HCB (P<0.05), followed by the HC group, and significantly lowest in the Com group (P<0.05). The larval survival rate for one week was significantly higher (P<0.05) in the Asian catfish fed the HCB diet than in those fed the Com or HC diet (P>0.05). In conclusion, elevating dietary carbohydrates in the diet from 7.70% to 22.73% (i.e., Com to HC diet, respectively) did not negatively affect the growth and reproductive performance of the Asian catfish. Further supplementation of benfotiamine at 0.02% to the HC diet enhanced significantly both the growth and reproductive performance of the Asian catfish. [ABSTRACT FROM AUTHOR]

This study investigated the heavy metal and hydrocarbon pollution status of Orashi River in four communities of Imo and Anambra States of Nigeria. Water and fish (Oreochromis niloticus and Clarias gariepinus) samples were collected from the river in the dry and wet seasons. Hydrocarbon and physicochemical parameters were determined in water with standard methods. Water and fish muscles were digested and analysed for metals using atomic absorption spectrophotometry. Results of analyses indicated hydrocarbon pollution. Hardness, alkalinity, nitrate, chloride, phosphate, and sulphate were significantly higher (p < 0.05) in wet season samples. Arsenic was undetected in water samples, but higher cadmium and iron concentrations were recorded in the wet season samples. Lead concentrations in the wet season were higher at some sites than the World Health Organization guideline. Arsenic was detected in Clarias at three sites in both seasons, but iron concentrations were significantly higher (p < 0.05) than those of other metals. Lead concentrations in Clarias gariepinus were lower than the Codex limit (0.3 mg/kg) except in the muscle samples from four sites. Arsenic was undetected in Oreochromis niloticus muscle samples but concentrations for lead (0.851 ± 0.203–8.604 ± 1.264 mg/kg (dry season) and 0.627 ± 0.035–9.364 ± 0.786 mg/kg (wet season)) exceeded the Codex limits in all samples. Health risk indices for the species indicated potential risk to the population from the consumption of Oreochromis niloticus. However, hazard index and target carcinogenic risk values indicate that people in the communities do not face significant non-carcinogenic and carcinogenic risks from cadmium and lead intake by consuming the fish species. [ABSTRACT FROM AUTHOR]

Abstract Background This study investigated the effect of sublethal concentrations (0.0, 0.3, 0.6, and 1.2 mg·L-1) of herbicide oxadiazon (ODZ) on the activities of Ca2+-ATPase and Na+/K+-ATPase in juvenile Clarias gariepinus. Methods One hundred eighty juveniles of Clarias gariepinus (mean weight 58.88 ± 1.24 g and mean length 22.34 ± 1.52 cm) were randomly divided into four groups and exposed to sublethal concentrations (0.00, 0.3, 0.6, and 1.2 mg·L-1 ODZ) for 21 days in a static renewal bioassay system in which the herbicide and water were replaced completely every day. The changes in Ca2+- and Na+/K+-ATPase activities in the gill, kidney, liver, and heart of the fish were assayed on days 1, 7, 14, and 21. Result The result showed significant alteration in the activity of these membrane-bound enzymes. There was duration and concentration-dependent significant (p

Electrical discharges (EDs) in the African sharptooth catfish Clarias gariepinus were studied. Irregular monopolar EDs, lasting for 8–10 ms and longer, and more complex EDs, lasting for 20–50 ms and characterized by specific indentation of the discharge pattern, were recorded in pairs of individuals exhibiting both aggressive and defensive behavior. The pattern of long discharges was reconstructed by adding short EDs with different latencies and amplitudes. The conditions for the formation of long EDs with asynchronous activity of electromotor neurons and the possibility of coordinated operation of the electric generator and electroreceptor systems in catfish were considered, since an increase in the duration of EDs lowers the threshold of their perception. [ABSTRACT FROM AUTHOR]

Background: Aquaponics are food production systems advocated for food security and health. Their sustainability from a nutritional and plant health perspective is, however, a significant challenge. Recirculated aquaculture systems (RAS) form a major part of aquaponic systems, but knowledge about their microbial potential to benefit plant growth and plant health is limited. The current study tested if the diversity and function of microbial communities in two commercial RAS were specific to the fish species used (Tilapia or Clarias) and sampling site (fish tanks and wastewaters), and whether they confer benefits to plants and have in vitro antagonistic potential towards plant pathogens. Results: Microbial diversity and composition was found to be dependent on fish species and sample site. The Tilapia RAS hosted higher bacterial diversity than the Clarias RAS; but the later hosted higher fungal diversity. Both Tilapia and Clarias RAS hosted bacterial and fungal communities that promoted plant growth, inhibited plant pathogens and encouraged biodegradation. The production of extracellular enzymes, related to nutrient availability and pathogen control, by bacterial strains isolated from the Tilapia and Clarias systems, makes them a promising tool in aquaponics and in their system design. Conclusions: This study explored the microbial diversity and potential of the commercial RAS with either Tilapia or Clarias as a tool to benefit the aquaponic system with respect to plant growth promotion and control of plant diseases. [ABSTRACT FROM AUTHOR]

El objetivo del trabajo fue evaluar subproductos cárnicos (SC) por tres metodologías de procesamiento en dietas extrusadas para las etapas de pre-engorde y engorde de Clarias gariepinus en cultivo intensivo. Se utilizaron dos diseños de clasificación simple de cuatro tratamientos con tres repeticiones cada uno. Los tratamientos en el pre-engorde fueron tres dietas experimentales con 25,0 % de harina de pescado (HP) y subproductos deshidratados (HSC), ensilado químico elaborado con SC frescos (ESF) y SC cocidos (ESC), las que se compararon con el pienso SKRETTING® de 49,0 % de proteína (control). En el segundo bioensayo (engorde) se utilizaron las dietas con 15,0 % de HP e iguales variantes de SC y el pienso SKRETTING® de 44,0 % deproteína (control). En el pre-engorde se redujo el crecimiento de los peces cuando los SC se ensilaron frescos (71,36; 61,42; 69,98 y 68,05 gramos, g). Sin embargo, en el engorde se afectaron los pesos finales (125,11; 46,92; 49,66 y 116,90 g) y la conversión alimentaria (0,98; 3,72; 3,03 y 0,92) con ambos ensilados. La utilización de la HSC en ambas etapas de cultivo no afectó los indicadores productivos de los animales respecto a los controles. Se evidenció que la utilización de HSC fue la variante viable en la elaboración de alimentosnacionales para el desarrollo de los cultivos de bagres en sistemas de cultivo intensivo, con efecto económico positivo.

A major challenge in Clariid catfish seed production is our inability to induce voluntary captive spawning of the brooders. Since voluntary captive spawning had been previously elicited in a Clarias species by simulating natural breeding environment, we speculated that the major obstacle in voluntary spawning might be the absence of an inducing agent that triggers mating response in the brooders. To address the issue, oxytocin was injected to the brooders along with Ovatide (a commercial inducing agent comprising salmon gonadotropin‐releasing hormone analogue and domperidone). Administration of 40 mIU/kg body weight of oxytocin after 12 hr of Ovatide injection resulted in voluntary spawning of the fish (81.5%, i.e. 31 out of 38 trials), with more than 70% hatching rate in simple and low‐cost spawning facilities. Histology of male gonads indicated sustained gamete maturation and the gonads were observed to be visibly turgid in the fish that received both the hormones. In contrast, gamete maturation slackened after 10 hr in the control fish, injected with Ovatide only. Administration of oxytocin along with Ovatide was also observed to induce aggressive sexual behaviour among the males. Neither of the hormones, acting alone, could induce voluntary spawning in the fish or influence sexual behaviour. Our results clearly show that oxytocin plays a significant role in sustaining the male gamete maturation induced by Ovatide and trigger the behavioural mating response, leading to voluntary spawning in C. magur. The results hold potential to make a paradigm shift in the commercial catfish seed production technology. [ABSTRACT FROM AUTHOR]

The present investigation was carried out to find out the effects of high dose of L-lysine on the fish and also an attempt has been made to predict the impact on human health. L-lysine is an essential amino acid which is used in medical practices as a growth promoter of bones especially in infants. Important work on metabolism and functions of amino acids in human health and major diseases has been reported by many workers and evaluated the key role of various amino acids in response to infections. Lysine is not synthesized by body; therefore, it must be taken either by diet or supplementation. Lysine first of all isolated from casein in 1889 and introduced as Lysine hydrochloride in 1955. The recommended dose of lysine is 12mg/kg body weight. Side effects of Lysine in large doses i.e. 10-30gm/day may cause abdominal cramps and diarrhea but renal and hepatic toxicity is not reported in normal person. Amino acids are used to treat end stage renal failure and also in liver failure. Recently lysine is used to treat herpes and as a supplement for diabetic people. In present study the effect of acute high dose 2mg/100gm body weight of L-lysine in fish shows toxic effects on kidney and liver which is an alarming indication towards use of high dose of Lysine in man. In kidney it caused glomerular dilation of the capillaries, glomerular hemorrhages and cloudy swelling of renal tubules. In liver it leads swelling of hepatocytes, vacuolization, fatty degeneration and central vein dilation. These histopathological changes are supported by marked rise in level of blood urea, serum creatinine, blood sugar and serum cholesterol.

The role of the liver is the major site of detoxification and metabolism, so it was considered as a target organ in toxicological studies. The present study investigates the potential protective effects of Amphora coffeaeformis extract against hepatotoxic effects in African catfish, Clarias gariepinus induced by arsenic. The fish Clarias gariepinus was exposed to sub-lethal concentrations of arsenic; 19.2 and 38.3 mg/L (1/8 and 1/4 of 96h-LC50 value, 153.17 mg/L) for 15 days. Histopathological alterations of the liver were analyzed under light and transmission electron microscope (TEM). Using the light microscope, the alterations were hypertrophy and hyperplasia of hepatocytes, necrosis, melanomacrophage accumulation, lymphocytic aggregation and congested blood vessels as well as depletion in glycogen content. TEM investigation resulted in alterations in perichromatin granules that increased and progressively formed small clusters closely related with patches of heterochromatin. Also fractionation, dilation, and vesiculation of rough endoplasmic reticulum were observed in addition to mitochondrial hyperplasia, hypertrophy and cristolysis. Significant main effects were reported for glutathione and malondialdehyde levels (P< 0.05) after arsenic exposure. This arsenic-induced hepatotoxicity was improved with the dietary supplementation of Amphora. We concluded that Amphora extract can be used as a hepato-protective agent on arsenic-induced fish due to its biologically active components.

Heavy metals have different adverse impacts on different life stages of fish species with attempts to use natural antioxidants to counteract their effects. So, the present study investigated the potential protective effects of Amphora coffeaeformis extract against arsenic-induced hemato-biochemical alterations in African catfish, Clarias gariepinus. The fish exposed to sub-lethal concentrations of arsenic; 19.2 and 38.3 mg/L (1/8 and 1/4 of 96h-LC50 value, 153.17 mg/L) for 15 days. The main effect of arsenic was recorded in some blood parameters such as RBC’s count, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, and white blood cells. As for biochemical parameters, the main effect of arsenic was significant for alkaline phosphatase, glucose, uric acid, creatinine, albumin, globulin, and albumin/globulin. Also, the residue of arsenic in fish muscles showed significant effects. The majority of these arsenic-induced parameters were improved with dietary supplements of the diatom A. coffeaeformis. So, Amphora extract can be used as detoxification factor on fishes induced by arsenic due to its biologically active components providing protections like antioxidant, antiviral, antibacterial, and anti-inflammatory. Besides, they have excellent contents of proteins and carbohydrates which are supposed to enhance the effect of these compounds.

In this study, African catfish (Clarias gariepinus) was investigated under controlled conditions in recirculating aquaculture system (RAS). The experiment tested the effects of three different dietary prebiotics (FOS: fructooligosaccharide, GOS: galactooligosaccharide, and MOS: mannanoligosaccharide) in two levels (1 g/kg and 2 g/kg) and a control diet on the growth performance, survival rate, haematological and biochemical parameters, and small intestinal and liver histology of the African catfish. Better growth results were obtained in MOS (2 g/kg) supplementation, and there was a statistical difference (P < 0.05) between the MOS (2 g/kg) and the control group. Haematological parameters (erythrocyte sedimentation rate, red blood cell, white blood cell, lymphocyte, neutrophil, and glucose) were similar among all groups (P > 0.05) while some (alanine aminotransferase, aspartate aminotransferase enzymes, and monocyte) were significantly different (P < 0.05). The MOS (2 g/kg) group had longer villi length values than the control group. There was no difference among the groups in terms of small intestine histomorphology and liver tissues in fish. According to the results of this experiment, it can be said that MOS addition has a positive effect on growth parameters and could improve health conditions in Clarias gariepinus culture. [ABSTRACT FROM AUTHOR]

Background: This study investigated the effect of sublethal concentrations (0.0, 0.3, 0.6, and 1.2 mg·L-1) of herbicide oxadiazon (ODZ) on the activities of Ca2+-ATPase and Na+/K+-ATPase in juvenile Clarias gariepinus. Methods: One hundred eighty juveniles of Clarias gariepinus (mean weight 58.88 ± 1.24 g and mean length 22.34 ± 1.52 cm) were randomly divided into four groups and exposed to sublethal concentrations (0.00, 0.3, 0.6, and 1.2 mg·L-1 ODZ) for 21 days in a static renewal bioassay system in which the herbicide and water were replaced completely every day. The changes in Ca2+- and Na+/K+-ATPase activities in the gill, kidney, liver, and heart of the fish were assayed on days 1, 7, 14, and 21. Result: The result showed significant alteration in the activity of these membrane-bound enzymes. There was duration and concentration-dependent significant (p < 0.05) increase in Ca2+-ATPase activity in the treatment groups when compared with the control. The Na+/K+-ATPase activity was significantly (p < 0.05) inhibited in all the tissues when compared with control. The observed alterations in the activities of both Ca2+-ATPase and Na+/K+-ATPase in this study may be indication of impaired ionic transport and imbalance in the fish which may trigger other biochemical, physiological, and even neurological consequences that may compromise several body functions. Conclusion: The alteration of the ATPase activities in C. gariepinus by ODZ is likely to affect the ATP usage and energy metabolism in the fish serious repercussions on Ca2+ homeostasis, Na+/K+ sodium pump, and Ca2+/Na+ exchanger The results suggested that assay of the enzymes could be used as a biomarker of water pollution. [ABSTRACT FROM AUTHOR]

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Aquaculture of the African catfish Clarias gariepinus has rapidly increased in South-East Asia over recent years, which has now become one of the most cultivated species. This culture intensification has resulted in the development of various diseases, among which the Motile Aeromonas Septicaemia (MAS) caused by Aeromonas hydrophila. The present study aimed at investigating the potential of three plants, Piper betle, Psidium guajava, and Tithonia diversifolia, to prevent this disease using an enriched fish diet during 4 weeks. Though the minimum inhibitory and bactericidal concentrations of acetone–extracts were relatively high (2–32 mg mL−1 and 8–64 mg mL−1, respectively), all three plant powders imbedded in feed significantly reduced fish mortalities following an experimental infection with A. hydrophila, as indicated by relative percent survivals (RPS) ranging from 77 to 79%. When used in combination, the three plant extracts showed no interaction in vitro. Even though they improved RPS in comparison with controls, they were, however, less efficient in reducing mortalities than single plants. None of the plant-enriched diet had a clear effect on blood cell count or on reactive oxygen species (ROS) production (except for P. betle, which significantly increased ROS production after infection); however, both individual plants and their combinations significantly limited the drop of hematocrit following infection. Altogether, these results indicate that selection of plants for herbal therapy is complex and might depend on several in vivo criteria, and as such should not solely rely upon measurement of their antimicrobial activity. [ABSTRACT FROM AUTHOR]

The facultative air-breathing magur catfish (Clarias magur) frequently face different environmental challenges, such as hyper-ammonia, and desiccation stresses in their natural habitats. All these stresses lead to higher accumulation of body ammonia, thereby causing various harmful effects to the fish due to its toxicity. Nonetheless, the mechanisms underlying ammonia-induced toxicity is yet not clear. In the present study, we used RNA sequencing and utilized a modified method for de novo assembly of the transcriptome to provide an exhaustive study on the transcriptomic alterations of magur catfish in response to high environmental ammonia (HEA; 25 mM NH 4 Cl). The final contig assembly produced a total of 311,076 unique transcripts (termed as unigenes) with a GC content of 48.3% and the average length of 599 bp. A considerable number of SSR marker associated with these unigenes were also detected. A total of 279,156 transcripts were successfully annotated by using various databases. Comparative transcriptomic analysis revealed a total of 3453 and 19,455 genes were differentially expressed in the liver and brain tissues, respectively, in ammonia-treated fish compared to the control. Enrichment analysis of the differentially expressed genes (DEGs) showed that several GO and KEGG pathway terms were significantly over-represented. Functional analysis of significantly elevated DEGs demonstrated that ammonia stress tolerance of the magur catfish was associated with quite a few pathways related to immune response, oxidative stress, and apoptosis, as well as few transporter proteins involved with ammonia and urea transport. Both liver and brain tissues showed HEA-mediated oxidative damage with consequent activation of antioxidant machinery. However, elevated ROS levels led to an activation of inflammatory cytokines and thus innate immune response in the liver. Conversely, in the brain ROS-mediated irreversible cell damages activated apoptosis via both p53-Bax-Bcl2 and caspase-mediated pathways. The present study provides a novel understanding of the molecular responses of this air-breathing catfish against the ammonia-induced stressors, which could elucidate the underlying mechanisms of adaptation of this facultative air-breather living under various environmental constraints. • A modified method for de novo transcriptome assembly produced 311,076 unique transcripts. • HEA-induced oxidative damages in liver and brain were restrained by changes in the expression of antioxidant enzyme genes. • Multiple genes involved in immune defense response were augmented on HEA exposure in the liver. • Apoptotic genes were activated in brain on HEA exposure. [ABSTRACT FROM AUTHOR]

Abstract The facultative air-breathing magur catfish (Clarias magur) regularly encounter various environmental challenges including the exposure to nanomaterials discarded as industrial wastes in water bodies. The present investigation aimed at determining the possible ZnO NP-induced oxidative stress and also the antioxidant strategy of nitric oxide (NO), generated endogenously, in primary hepatocytes of magur catfish. Exposure of primary hepatocytes to different concentrations of ZnO NPs (5 and 10 μg/mL) led to a sharp rise of intracellular concentrations of hydrogen peroxide (H 2 O 2) and malondialdehyde (MDA) within 6 h, which decreased gradually at later stages. This phenomenon was accompanied by an initial decrease of superoxide dismutase (SOD) and catalase (CAT) activities, the expression of their corresponding genes and the enzyme protein levels, with a subsequent significant increase of all these parameters at later stages. Most interestingly, exposure to ZnO NPs also stimulated the NO production by the primary hepatocytes as a consequence of induction of inducible nitric oxide synthase (iNOS) activity, higher expression of nos2 gene and iNOS protein. Furthermore, when the NO production by the hepatocytes was inhibited by either aminoguanidine (inhibitor for iNOS) or BAY (inhibitor for NFκB) in the presence of ZnO NPs, the intracellular concentrations of H 2 O 2 and MDA was significantly elevated. This elevation was accompanied by a subsequent decrease of sod and cat genes expression, thereby suggesting that the inhibition of NO production leads to oxidative stress. Thus, it is believed that the magur catfish uses the strategy of stimulation of endogenous NO production by inducing the nos2 gene and simultaneous NO-mediated induction of sod and cat genes to defend against the NP-induced oxidative stress. It is the first report of such NO-mediated antioxidant strategy in any teleost fish to defend against the NP-induced oxidative stress and corresponding cellular damages. Highlights • ZnO NPs cause oxidative stress in primary hepatocytes of C. magur. • ZnO NP-mediated oxidative stress induces NO production by inducing the nos2 gene. • Endogenously produced NO induces the expression of antioxidant sod and cat genes. • First report of endogenous NO-mediated antioxidant strategy in any teleost fish. [ABSTRACT FROM AUTHOR]

This study was conducted to illustrate the effect of dietary gelatinized starch (GS) on the growth performance, enzyme activities and expression of MyoD and Myf5 in magur, Clarias batrachus fingerlings. Four iso‐nitrogenous (37%) and iso‐lipidic (6%) diets containing 15% (D‐1), 25% (D‐2), 35% (D‐3) or 45% (D‐4) GS were fed to 240 fingerlings (2.5 ± 0.5 g) in triplicates groups for 8 weeks. The maximum weight gain %, specific growth rate, protein efficiency ratio, lower FCR and higher mRNA expression of MyoD or Myf5 were found in the D‐3 group fed with 35% GS. Higher hepatosomatic index, viscerosomatic index, body lipid and lower moisture content were found in the D‐4 group. Aspartate transaminase and alanine transaminase activities were found to be higher in the D‐1 group. Amylase, glucose‐6‐phosphate dehydrogenase and blood glucose were higher in the D‐4 group. Superoxide dismutase, catalase and hexokinase activities remain unaffected by the dietary GS levels. Hence, the overall results indicate that 35% GS can improve growth performance and upregulate myogenic regulatory factors, but 45% GS level will favor lipogenesis and compromise growth. Furthermore, Myf5 gene showed more immediate response than the MyoD to the dietary carbohydrate in magur. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of Euphorbia hirta leaf extract on the growth performance, hematological and organosomatic indices of hybrid catfish, Clarias macrocephalus × C. gariepinus. The fish were treated with 0 (control), 300, 500 and 800 mg/kg (ppm) for 90 days. The weight gain, average daily growth rate, and specific growth rate were at significantly higher levels in fish from all the treatment groups on days 75 and 90, while the feed efficiency and protein efficiency ratio were consistently higher in fish from all the treatment groups from day 60 up until day 90. The feed conversion rate significantly decreased from day 60 until day 90 in all treatment groups when compared with the control group, and the survival rate was significantly different from day 30 until day 90; a consistently higher rate was observed in fish fed 800 mg/kg. The highest viscerosomatic index and intraperitoneal fat were observed in the group fed 500 mg/kg (p < 0.05). The hepatosomatic index was significantly increased alongside increasing levels of E. hirta extract. The total white blood cell count in the control group was significantly higher on day 30, but on day 90 all the treatment groups showed higher levels. Hematocrit percentage was significantly different on days 30 and 90. Lymphocyte, eosinophil and thrombocyte levels were shown to be significantly different (p < 0.05) when different groups of fish were compared. In conclusion, 300 mg/kg of E. hirta leaf extract could improve growth performance, hematological and some organosomatic indices in hybrid catfish. [ABSTRACT FROM AUTHOR]

Bighead catfish ( Clarias macrocephalus ) is an important freshwater species for aquaculture and fisheries in Southeast Asia. The species has been domesticated for more than 30 generations in hatcheries, but wild population numbers have declined to “threatened” levels. In this study, genetic diversity was quantified in areas of intensive catfish culture and natural areas of the Mekong Delta, Viet Nam to inform hatchery genetic improvement programs and conservation actions. Fish were collected from three hatcheries and four wild populations in conservation parks (wild-conservation) and seven wild populations in rice fields of aquaculture-intensive areas (wild-farming). Results based on six microsatellite loci showed all populations had relatively high levels of genetic diversity for allelic richness (range 8.10– 10.18), and observed heterozygosity (range 0.708– 0.819). However, genetic diversity was lower in hatchery fish and wild farming populations as evidenced by significantly lower (P ≤ 0.03) allelic richness (9.16 ± 0.27 and 9.27 ± 0.66, respectively) than wild conserved populations (10.01 ± 0.19). Pairwise individuals’ genetic relatedness within three cultured populations (0.013–0.028) and five wild farming populations (0.016–0.039) indicated low potential for inbreeding in the immediate future. Genetic differentiation among populations (F ST  = 0.017 ± 0.002) indicated a modest level of gene flow, likely due to the expansive river network, straying of hatchery fish, and large-scale transport of wild fish to hatcheries. [ABSTRACT FROM AUTHOR]

The triangle between the Kavango and Kunene rivers is drained by the Cuvelai, an ephemeral and deltaic drainage system covering more than 100 000 km2. In good rainfall years, the area becomes populated by fish communities dominated by five species migrating southward towards the endorheic Etosha Pan, the basin’s terminal sump. When water dries up, fish subsequently die-off and their sudden appearance in rainy years has captivated scientists for decades. The current study was prompted by hitherto untapped indigenous knowledge through narratives of opportunistic fish harvesting of migrating fish at temporary connections between the Kunene River and the Cuvelai- Etosha Basin. A reconnaissance fish survey in 2017 was complemented by digital satellite images and elevation data analyses. Results support the presence of at least three major ephemeral fish migration routes. The dominant fish genera migrating upstream in Kunene tributaries comprise Enteromius, Oreochromis and Clarias, all eurytopic and known to undertake upstream, lateral and downstream migrations on floodplains. Although other notable fish refugia in the Cuvelai-Etosha Basin are yet to be identified, there is a necessity for the protection and management of these migration routes in tandem with studies on the nature and extent of this inter-basin fish migration under climate change and variability. [ABSTRACT FROM AUTHOR]

Reference genes employed for normalizing quantitative PCR data are important for the accurate analysis of gene expression. To date, no reference genes have been screened for developmental gene expression studies in Clarias magur. In the present study, three commonly used and constitutively expressed genes viz. beta actin (β- actin), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and elongation factor-alpha 1 (EFa1) were examined for their efficacy as internal control to avoid any variation during qRT-PCR expression analysis at different developmental stages of C. magur. All the selected housekeeping genes showed a variable level of mRNA expression during the developmental stages of C. magur. Using three independent statistical algorithms (delta-CT, BestKeeper and NormFinder), β-actin and GAPDH were identified as the suitable genes at different developmental stages. However, comprehensive gene stability evaluation denoted β-actin to be the most stable gene for carrying any gene expression studies. The present results, recommend β-actin as the optimal housekeeping gene for qRT-PCR analysis during different developmental stages of C. magur. [ABSTRACT FROM AUTHOR]

Abstract: Ultraviolet‐A light (UVA)‐induced DNA damage and repair in red blood cells to investigate the sensitivity of African catfish to UVA exposure is reported. Fishes were irradiated with various doses of UVA light (15, 30, and 60 min day−1 for 3 days). Morphological and nuclear abnormalities in red blood cells were observed in the fish exposed to UVA compared with controls. Morphological alterations such as acanthocytes, crenated cells, swollen cells, teardrop‐like cells, hemolyzed cells, and sickle cells were observed. Those alterations were increased after 24 h exposure to UVA light and decreased at 14 days after exposure. The percentage of apoptosis was higher in red blood cells exposed to higher doses of UVA light. No micronuclei were detected, but small nuclear abnormalities such as deformed and eccentric nuclei were observed in some groups. We concluded that exposure to UVA light induced DNA damage, apoptosis, and morphological alterations in red blood cells in catfish; however, catfish were found to be less sensitive to UVA light than wild‐type medaka. [ABSTRACT FROM AUTHOR]