Effect of the Dietary Substitution of Fish Meal with Achatina fulica Meat Meal on the Growth Performance and Production Cost of African Catfish (Clarias gariepinus) Fingerlings

Fishmeal is the most preferred source of protein in aquafeeds, but it is expensive and scarce. Hence, Achatina fulica meat meal (AFM), which is much less preferred for human consumption out of three species of African giant land snails, was tested as a fishmeal substitute for Clarias gariepinus growth. Five iso-nitrogenous and iso-calorific diets were formulated, in which AFM substituted fish meal at 0% (control or Diet A), 25% (Diet B), 50% (Diet C), 75% (Diet D) and 100% (Diet E). These dietary treatments were each replicated thrice in a completely randomized design experiment, using 36-L plastic tanks in which the fish were fed daily rations corresponding to 5% of their body weight, for 8 weeks. Water quality parameters in the tanks were monitored. Proximate analyses were conducted on the fish meal, snail meal and experimental diets before the feeding trials. Cost-benefit analysis of the different diets was performed. The crude protein content of AFM (69.18%) was significantly higher than that of fish meal (55.81%). There was no significant difference (P > 0.05) in the mean weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio and survival rate in fish fed Diet A and Diet B. The best protein efficiency ratio (0.77) was recorded in fish fed Diet B. Furthermore, the survival rate of fish increased with increased levels of AFM substitution. Water quality parameters were within a suitable range for tropical fish culture, indicating that the AFM did not pollute the water. The fish fed 25% AFM diet significantly (P Clarias gariepinus diets at a 25% substitution level. The aquaculture industry can thus exploit the availability of this feed resource.

Fruit Powder of Tetrapleura tetraptera in Local Feed on Some Zootechnical Performances of Juveniles of Clarias gariepinus in Concrete Tank

This study focused on the supplementation of four-sided spice fruit powder (Tetrapleura tetraptera) on some zootechnical performances of juveniles of Clarias gariepinus and was carried out from February 14 to July 20 at the Massoma Fish Farm of Bojongo Mbeidi located in the Littoral Region, Department of Wouri, Douala IV district. The farm benefits from a climate favorable to aquaculture activity. For this purpose, five (5) treatments were tested including T0+ (imported feed), T0-, T0.3, T0.4, and T0.5 respectively for the treatments with 0% supplemented food;0.3%;0.4% and 0.5% of Tetrapleura tetraptera powder. A total of 450 Clarias gariepinus fry with an initial average weight of 7 ± 1.5 g, were distributed in happas of 0.49 m2 each placed in Triplicate in a completely randomized device. Four isoprotein foods with 38% crude protein were formulated to feed these fry at 7% of their biomass per day for 15 days then to their fullness until the end of the experiment. Intermediate fishing was carried out every fortnight. 75 days later, the results recorded show that the highest average survival rate (96.44% ± 3.5%) was recorded with the subjects fed feed supplemented with 0.4% T. tetraptera powder. The average weight (120.93 ± 67.20), weight gain (113.93 ± 67.20), specific growth rate (3.64 ± 0.79% g/d) and total lengths and standard (26.43 ± 1.9 and 23.66 ± 1.76) the highest were recorded with the T0+ treatment (imported feed). The highest conditioning factor K (2.14 ± 0.15) was recorded with the treatment supplemented with 0.4% T. tetraptera. The lowest conversion ratio (1.28) was recorded with the treatment fed with imported blue crown food (T0+). Furthermore, the lowest production cost was recorded with the treatment supplemented with 0.4% T. tetraptera. It appears from this study that the juveniles of C. gariepinus better value the feed substituted with 0.4% of the powder of four sides (Tetrapleura tetraptera).

Studies on Heavy Metals Levels in Hepatic Tissues of Cat Fishes(Clarias gariepinus)from River Ibi,Donga and Gindin-Dorowa in Taraba State Nigeria,in Relation to key Enzyme of heme Biosynthetic Pathway

Fishes are excellent markers of the extent of pollution from heavy metals in aquatic environments given that they are found at various levels of the food chain.This study aimed to investigate the bioaccumulation of heavy metals(Zn,Pb,Cd,As,and Hg)as well as the activity of delta-aminolevulinic acid dehydratase(δ-ALA-D)in the livers of cat fishes(Clarias gariepinus)collected from three rivers(Donga,Ibi and Gindin-Dorowa)in Taraba State,Nigeria.The concentrations of heavy metals in the liver tissues were determined using an atomic absorption spectrophotometer in accordance with the method of AOAC(2019),while theδ-ALA-D activity was assayed using the method of Sassa(1982).Results revealed that only Zn and As were present in the liver samples from the three rivers.Pb was found only in the liver from Gindin-Dorowa at the concentration of 0.0012mg/kg which is not significant(P<0.05)when compared with other locations,while Hg and Cd were absent in all the liver samples.The liver sample from Gindin-Dorowa had the highest concentration of Zn(4.2500 mg/kg),followed by Ibi(3.2067 mg/kg),and Donga having the least(2.5500 mg/kg),which were all substantially(P<0.05)different from one another.However,there was no significant(P<0.05)difference in the As composition of liver from Donga(0.0013 mg/kg),Ibi(0.0012 mg/kg)and Gindin-Dorowa(0.0010 mg/kg).The result ofδ-ALA-D activity showed that the highest enzymatic activity was found in the liver sample from Donga which has the least Zn and no Pb content,followed by Ibi sample.This validates the report that heavy metals impairδ-ALA-D activity.Nonetheless,the concentrations of all metals in fish livers from all regions do not exceed the acceptable limits set by international law,making them safe for human consumption and possibly not having a negative impact on public health.Since there is little or no industrial activity in the studied locations,these levels may be consequent to low anthropogenic inputs.The current situation should be safeguarded to prevent pollution of the river’s aquatic biota in the near future,and more appropriate steps should be made to guarantee higher fish quality and life in the rivers.

Investigation of heavy metals and lipid peroxidation level in the muscles of Clarias gariepinus from IBI,Gindin-Dorowa and D onga community rivers in Taraba State,Nigeria

Heavy metals have harmful effects on human health,and exposure to these metals has been increased by industrial and anthropogenic activities and modern industrialization.Heavy metals content of the liver tissues was determine d using Atomic Absorption Spectrophotometer method,while lipid peroxidation was carried out.Heavy metals analyzed include;lead(Pb),cadmium(Cd),zinc(Zn),Arsenic(As),and Mercury(Hg).The findings revealed that the heavy metal Zinc(Zn)has high concentrations in the muscles of the fish species,the concentration of this heavy metal Zinc is high in River Gindin Dorowa th a n in River Ibi and River Donga shows less concentration of this heavy metal though it’s above WHO permissible limits.Results revealed that only Zn and Cd were present in the muscle from the three rivers.Pb was found only in the liver from Gindin-Dorowa at the concentration of 0.017 mg/kg,which is not significant(P<0.05)when compared with other locations,while Hg and As were absent in all the muscle samples.The highest concentration of Zn was found in the muscle sample from Gindin-Dorowa(7.450 mg/kg)followed by Ibi(6.16 mg/kg)and the least being Donga(4.365 mg/kg)which are significantly(P<0.05)different from one another.However,there was no significant(P<0.05)difference among the Cd composition of muscle from Gindin-Dorowa(0.025 mg/kg),Donga(0.024 mg/kg)and Ibi(0.015 mg/kg),respectively.The TBA was found in the hepatic tissue sample from Gidin-Dorowa,which has the highest Zn,Cd and no Pb content,followed by Ibi and then the Donga sample.This suggests that there is a positive relationship between heavy metals and the effect of TBA on the hepatic tissues,justifying the fact that heavy metals affect the hepatic tissues of fish,while on the cerebral tissue.In conclusion,it revealed that there is a negative relation between heavy metals and the effect of TBA on the cerebral tissues to protect or save aquatic habitat s of fish quality and aquatic life.

Haematological and Hepatic Responses of the African Catfish Clarias gariepinus to Sublethal Exposure of Industrial Effluents from Ologe Lagoon Environs,Lagos,Nigeria

The present study is on the haematological and hepatic responses of the African catfish fingerlings Clarias gariepinus to sublethal toxicity of industrial effluents(IE)from the environment of Ologe Lagoon,Lagos,Nigeria.The fish were cultured in five concentrations of industrial effluents:0%(control),5%,15%,25%,and 35%.Trials were carried out in triplicates for twelve(12)weeks.The culture system was a static renewable bioassay and was carried out in the fisheries laboratory of the Lagos State University,Ojo-Lagos.Weekly physico-chemical parameters:Temperature(°C),pH,conductivity(ppm)and dissolved oxygen(DO in mg/L)were measured in each treatment tank.Haematological parameters:packed cell volume(PCV),red blood cells(RBC),white blood cell(WBC),neutrophil and lymphocytes etc.,and hepatological alterations were measured after 12 weeks.The physico-chemical parameters showed that the pH ranged from 7.82±0.25~8.07±0.02.DO ranged from 1.92±0.66~4.43±1.24 mg/L.The conductivity values increased with increase in concentration of I.E.While the temperature difference remained insignificant with mean value range between 26.08±2.14~26.38±2.28.The DO showed significant differences at p<0.05.Though survival was 100%during the sublethal study,haematological results showed that C.gariepinus had PCV ranging from 13.0±1.7~27.7±0.6,RBC ranged from 4.7±0.6~9.1±0.1,and neutrophil ranged from 26.7±4.6~61.0±1.0 amongst others.The highest values of these parameters were obtained in the control and lowest at 35%.While the reverse effects were observed for WBC and lymphocytes,the liver shows normal liver cells in the control(0%),but at higher toxic levels,there were:vacoulation,destruction of the hepatic parenchyma,tissue becoming eosinophilic(i.e.tending towards Carcinogenicity)and severe disruption of the hepatic cord architecture.This study therefore shows that disposal of effluents into the aquatic environment affects the health of fishes by impairing normal hepatic functions and hindering vital physiological processes if exposure continues for a long period of time(sublethal effect).

Growth Performance and Serum Lipids Profile of Clarias gariepinus Catfish Following Experimental Dietary Exposure to Fumonisin B1

Fumonisin B1 (FB1) is produced by fungus of the genus Fusarium (Fusarium verticiloides and F. proliferatum), and occurs predominantly in maize. The consumption of feed contaminated with FB1 has been reported to cause deleterious effects in some fish species. This study was designed to determine the effects of dietary FB1 on growth and lipids profile of Clarias gariepinus. 450 juvenile catfish were stocked into 5 groups of tanks consisting of 3 tanks per group and fed one of five diets amended with FB1 (0.0 mg;10.0 mg;20.0 mg;40.0 mg and 80.0 mg FB1/kg) for 56 days. At time point’s day 7, 14, 28 and 56, five fish were sampled from each tank weighted, length measured and bled for of lipids profile determinations. Results show that there was a significant reduction (P < 0.05), in the mean body length of the fish fed diets amended with various amounts of FB1 compared with those fed control diet;also, there was a significant reduction (P < 0.05) in the weight gain of fishes fed diets amended with FB1 compared with the control. The specific growth rate and the feed conversion ratio at 56 days shows fish fed 0.0 mg FB1/kg had the highest specific growth rate (0.39 ± 0.14%/day) and the lowest feed conversion ratio (0.59 ± 0.01) whereas, fish fed 80.0 mg FB1/kg had the least specific growth rate (0.07% ± 0.01%/day) and the highest feed conversion ratio (1.95 ± 0.11). Dietary FB1 caused significant increases (P < 0.05) in serum cholesterol, HDL-C;LDL-C;triglycerides and the sphinganine-sphingosine ratio. Dietary FB1 at an inclusion rate ≥ 20 mg FB1/kg of diet produced significant reduction in weight gain and hyperlipidemia marked by hypercholesterolemia, increased blood high-density lipid cholesterol, increased blood low-density lipid cholesterol, elevated blood triglycerides and elevated sphinganine-sphingosine ratio.

Ameliorative Effects of Spirulina platensis on Deltamethrin-Induced Biochemical Alterations and Oxidative Stress in the African Catfish;Clarias gariepinus

The present study was carried out to determine LC50 of deltamethrin (DM) in the African catfish;Clarias gariepinus, investigate its effects on the biochemical parameters and the antioxidant status of various tissues, and assess the protective role of Spirulina platensis (SP) against DM induced toxicity in C. gariepinus. The fish were distributed into seven groups of 10 fish/each for 30 days as follows: Group 1, control;Group 2, orally administered saline;Group 3, oral SP (150 mg/kg b.w.);Group 4, exposed to 5.19 μg/l DM;Group 5, exposed to 5.19 μg/l DM and orally administered SP (150 mg/kg b.w.);Group 6, exposed to 12.97 μg/l DM;and Group 7, exposed to 12.97 μg/l DM and orally administered SP (150 mg/kg b.w.). Results revealed marked elevation in serum AST, ALT, ALP, creatinine, urea and uric acid. Significant decrease in serum total protein and albumin was recorded. At the same time, the level of malondialdehyde (MDA) was significantly increased in liver, kidney and gills. While, tissue level ofGSHand, SOD,CATandGSH-Px activities were reduced. Treatment with SP improved the biochemical parameters and attenuated the DM induced oxidative damage. Therefore, this study confirmed the protective role of SP as an antioxidant against the toxicity of DM in catfish.

Isolation and Identification of Bacteria Found in the Milt of Cultured Clarias gariepinus

This study investigated bacteria that are associated with milt in cultured samples of African catfish-Clarias gariepinus.Male broodstocks of Clarias gariepinus were collected from private Fish Farm in Ogun State,Nigeria,while the fish’s milt was collected and analyzed for microbial load at laboratory of the Department of Microbiology,Federal University of Agriculture,Abeokuta,Ogun State.The molecular characterization of the amplicon was done at International Institute of Tropical Agriculture,Ibadan.Bio-edit was used for importing and mining nucleotide sequences into gene bank.As revealed by the results,bacterial organisms that were present in the milt of Clarias gariepinus are Aeromonas caviae,Proteus mirabilis,Serratia rubidaea,Pseudomonas mosselii,Acinetobacter soli and Klebsiella variicola.The Basic Local Alignment Search Tools revealed the percentage similarity ranging from 86%-97.04%and their accession numbers.These bacteria indicated high levels of faecal contamination in the environment.In conclusion,bacteria were found in the milt of cultured catfish and are capable of being pathogenic to humans and may increase the vertical transfer to fry during breeding and rearing stage.Therefore,fish farmers should maintain a hygiene and serene environment during breeding and culturing of catfish.

Effects of Dietary Replacement of Maize with Sweet Potato Peel in the Diet of African Catfish Clarias gariepinus(Burchell,1822)

This study was carried out to evaluate the effects of dietary replacement of maize with sweet potato peel in the diet of Clarias gariepinus juveniles.The levels of the SPP inclusion in the experimental diets were 0%,25%,50%,75%and 100%.All the diets were iso-nitrogenous.One hundred and fifty(150)C.gariepinus juveniles(33 g~35 g)were randomly distributed to five treatments with three replicates each and 5%of their body weight for 12 weeks.Fish carcass proximate compositions analyzed before and after feeding with the experimental diets shows that CP and EE differed significantly(p<0.05)among the experimental fish and the control,except the percentage CP of the fish fed SPP0%and SPP50%in which there was no significant difference(p>0.05).Highest MWG of 207.70±25.95 g was obtained in the fish fed SPP100%followed by 191.30±16.15 g obtained in the fish fed SPP75%.The least MWG of 149.83±16.01 g was recorded in fish fed SPP25%.The highest FCR of 3.61±0.45 g was recorded in the fish fed SPP100%.A steady decrease in FCR was observed with decreasing inclusion levels of SPP meal.However,higher FW,FL,SGR and PER were observed in the experimental fish as from 50%inclusion levels of the SPP.The cost of feed per kg was reduced and the NP and WG increased with increasing levels of SPP and the profitability was enhanced at 100%SPP inclusion level.The results revealed that C.gariepinus juvenile could tolerate up to 50%,75%and 100%inclusion levels of SPP.The best growth performance was recorded in the fish fed SPP100%,therefore,sweet potato peel can replace maize in the diet of C.gariepinus without any inauspicious effect on the growth performance and nutrient utilization.

Acute Toxicity and Behavioural Responses of African Catfish,Clarias gariepinus to Amine Salt of 2,4-D

Fingerlings of African catfish,Clarias gariepinus [mean total length,(7.0±1.0) cm SD;mean weight,(3.0±0.7) g SD] were exposed to acute concentrations of amine salt of 2,4-D(0,50,200,250,350,and 400 mg/L) to determine the behavioural responses and mortality.When raised in aquaria the fish became hyperactive.The beat frequencies(opercular and tail beat frequency per minute,OBF and TBF) of the exposed fish declined with increase in the exposure duration and concentration,but the reverse was the case with percent mortality.These variables signifi cantly differed at both the exposure duration and concentration of the toxicant(P<0.05).Anova of the linear regression between variables-OBF,TBF and mortality on exposure duration indicated a strong positive relationship(P<0.001) with the entire variables except mortality and exposure duration.OBF and TBF were inversely correlated with exposure duration(r=-0.99;P<0.05).The 96 h lethal concentration was 165.36(133.29～190.51,C.L.) mg/L and the median lethal time at the highest concentration was 20.41(11.87～27.46) h.The results from this study revealed that 2,4-D was very toxic to C.gariepinus under laboratory conditions and its application should therefore,be restricted in the field.

Differential inhibitory potentials of three plant extracts against Dermestes maculatus Degeer and microorganisms in smoked catfish, Clarias gariepinus Burchell

Objectives:Three medicinal plants:Zingiber officinale rhizome,Allium sativum bulb,and Moringa oleifera seeds,were evaluated for progeny inhibition in fish beetle,Dermestes maculatus,and incidence of bacteria and fungi in smoked-dried Clarias gariepinus.Materials and Methods:Cleaned C.gariepinus were separately soaked in extracts of these selected plants(50 g/1000 ml)for 60 min before smoke-drying in a mud kiln at 105℃ and later divided into lots.Sensory evaluation was conducted on uninfested fishes in lot A while fishes in lot B was artificially infested with five pairs of newly emerged adult D.maculatus for 10 days.Number of emerged larva,adult insects,and incidence of microorganisms before and following 90 days in storage after infestation were used as indices of potency of the extracts.Results:Results obtained showed that all the treated uninfested smoked-dried C.gariepinus retained high scores for taste,texture,aroma,and appearance within the first 5 weeks of storage after smoking when compared with the control.This implied that the tested extracts had no negative effect in terms of sensory attributes on the treated fish during storage and can therefore be used for fish preservation.Meanwhile,A.sativum among all the selected extracts had the least number of larvae(17.67±1.45),adult(21.00±1.53),fungi(9.00×10^(2)±0.53 sfu/ml)and bacteria counts(11.33×10^(2)±0.33 cfu/ml)following 90 days in storage after infestation.Conclusion:Allium sativum among the tested extracts proved to be most effective and could be recommended for control of D.maculatus and microorganisms in smoked C.gariepinus.

Occurrence of Cryptosporidium species in catfish(Clarias gariepinus)Harvested from two lakes and artificial ponds in Zaria,Northern Nigeria

Objective:To determine the occurrence of Cryptosporidium species in catfish(Clarias gariepinus)harvested from two lakes and ponds in Zaria,Kaduna State,Nigeria.Methods:Catfish samples(n=200)from two lakes and(n=200)from two private fish ponds were collected and their gills and gastrointestinal tract samples were analysed for Cryptosporidium oocysts using modified Ziehl-Neelsen staining technique was used,followed by microscopy.Results:Oocysts of Cryptosporidium species were found in all the sampling sites with an overall positivity rate of 49.75%.A comparison between the lakes and ponds as sampling sites revealed a statistically significant(P<0.05)higher percentage of occurrence of Cryptosporidium oocyst from the lakes(39.25%)than from the ponds(10.50%).Conclusions:These findings document for the first time the natural occurrence ofCryptosporidium sp.in catfish intended for human consumption and therefore,underlines the need for public enlightenment to guard against any possible zoonotic transmission.

Monogenean parasites of the African catifsh Clarias gariepinus from two ifsh farms in Calabar,Cross River State,Nigeria

Objective:To determine the prevalence,mean intensity,and abundance of monogenean parasites in Clarias gariepinus(C.gariepinus)from two selected fish farms in Calabar,Cross River State,Nigeria.Methods:Eighty specimens of C.gariepinus from the two farms(40 each)were necropsied for parasitological analysis.Skin,gill and fin biopsies were prepared from each specimen following standard methods for microscopic analysis.Parasitological indices including dominance(D),prevalence,mean intensity and abundance were calculated according to standard formulae.Data were analyzed using the Fisher's exact test.Results:C.gariepinus from the two farms were infested with a total of ninety individuals of monogenean parasites belonging to three species including Macrogyrodactylus clarii(M.clarii),Gyrodactylus sp.and Dactylogyrus sp.D index showed that the three monogenean species were eudominant(D-value>10%).Gyrodactylus sp.was more abundant(46)followed by Dactylogyrus sp.(23)while M.clarii was the lowest(21).Prevalence,meaning intensity and abundance of monogenean parasites in the two farms,varied insignificantly higher(P>0.05).Prevalence in both farms were higher in female C.gariepinus than that in male.Monogenean parasites exhibited organ specificity as M.clarii and Dactylogyrus sp.were recovered from the gills while Gyrodactylus sp.colonized the skin and fin.Conclusions:High abundance of these parasites may lead to poor growth performance and high mortality in C.gariepinus,leading to huge monetary loss and low profit margin by increasing production cost due to the cost of treatments.

Effect of aqueous extract of Polygonum minus leaf on the immunity and survival of African catfish(Clarias gariepinus)

Objective:To establish immunomodulatory potential of aqueous extract of Polygonum minus(P.minus)leaves,the haematological effects and lysozyme activity of aqueous extract of P.minus leaf on Clarias gariepinus was studied.Methods:The fish were grouped and administered with the P.minus aqueous leaf extract intraperitoneally.Blood and serum samples were collected from each group and examined for various blood parameters.The turbidimetric assay for lysozyme activity using M.luteus and the survival rate of fish against A.hydrophila was carried out.Results:There was no significant impact(P>0.05)on white blood cell count,red blood cell count,mean corpuscular volume,mean corpuscular hemoglobin,mean corpuscular hemoglobin concentration and lysozyme activity was significantly(P<0.05)higher than control.The serum glutamic oxaloacetic transaminase and serum glutamic pyruvic transaminase levels were significantly lower than control(P<0.05).The highest dose group showed longest survival.Conclusions:From this study,it is considered that the aqueous extract of P.minus can be used as an immunostimulant in African catfish,but continuous administration may require maintaining the protection.

Fecundity studies of the African catfish Clarias gariepinus(Burchell,1822)fed Coppens feed and Unical aqua feed in circular concrete tanks

Objective:To determine and compare the fecundity of Clarias gariepinus(C.gariepinus)fed with Unical aqua feed and Coppens feeds in concrete tanks,including the nature of relationship that exist between fecundity and morphometric indices of fish such as total length and total weight.Methods:An experiment was conducted for 6 months in the fish farm of University of Calabar with two triplicate groups of 50 C.gariepinus post-fingerlings.The experimental fish weighing(0.50±0.02)kg were stocked in concrete tanks(circular)of 16.63 m^(2)area.The tanks were labelled A_(1),A_(2),A_(3),B(1),B(2)and B(3).Fish in tank A_(1),A_(2)and A_(3)were fed with Coppens feed and fish in tanks B(1),B(2)and B(3)were fed with Unical aqua feed.Feeding was done twice daily(9:00 and 16:00)at 3%of their body weight.Results:Mean fecundity of C.gariepinus fed with Unical aqua feed(68366.67±15966.29)eggs varied significantly(P<0.05)from C.gariepinus fed with Coppens feed(61833.83±11692.31)eggs.A linear relationship was observed between fecundity and biometric indices(total length,total weight and ovary weight)of C.gariepinus fed with the two feeds.Food conversion efficiency of C.gariepinus fed with Coppens feed(50.94%±0.91%)was insignificantly higher(P>0.05)than C.gariepinus fed with Unical aqua feed(50.37%±1.29%).Water quality parameters including ammonia(mg/L),pH,water temperature(°C)and dissolved oxygen(mg/L)fell within the recommended range for the culture of fresh water fish.Conclusions:Fecundity of C.gariepinus reared in concrete tank was significantly influenced by the experimental feed.Therefore,on the bases of affordability and availability to farmers,Unical aqua feed is more economical and is recommended as a cost-effective cultivation of female C.gariepinus broodstock.

Physiological effects of paraquat in juvenile African catfish Clarias gariepinus(Burchel 1822)

Objective:To investigate the physiological effects of paraquat in African freshwater catfish Clarias gariepinus.Methods:Two sublethal test concentrations of paraquat(1.37 and 2.75 mg/L)were chosen based on the 96 h LC_(50)value(27.46 mg/L).Some experimental fish were exposed to these concentrations and control group for 15 d.Peripheral blood samplings were taken at intervals for assessment of haematological and biochemical parameters.Results:Exposure to paraquat affected behaviour and morphology of Clarias gariepinus.There were significant decreases(P<0.05)in the mean values of hemoglobin,red blood cells,packed cell volume,cellular hemoglobin,and cellular hemoglobin concentration.The levels of white blood cells,glucose,aspartate aminotransferase,and alanine aminotransferase significantly increased(P<0.05)while protein levels declined.However,no definite pattern of changes was observed in the number and type of leucocytes.Conclusions:The results of the present study indicate that paraquat is toxic and has the potential to impair on the physiological activities in African catfish Clarias gariepinus.The use of paraquat should be strongly controlled and carefully monitored to avoid the possible damage done to the environment.

Assessment of some heavy metals in the tissues(gills,liver and muscle)of Clarias gariepinus from Calabar River,Cross River State,South-eastern Nigeria

Objective:To assess the pollution status of Calabar River in relation to the levels of heavy metal in the tissue of the African catfish[Clarias gariepinus(C.gariepinus)].Methods:A total of 45 samples of C.gariepinus were purchased from fishermen on landing at Nsidung beach along Calabar River within three months(15 samples monthly)from June to August,2014.The samples were then put into a cold box containing ice blocks immediately after buying from the fishermen.The fish samples were transported immediately to the Chemistry Laboratory,University of Calabar for digestion and heavy metal analysis.Portions of the muscle,gills and liver were removed from the fresh samples and oven dried at temperature of 120°C to constant weight and digested using standard methods.The digested tissue portions were analyzed for lead,iron,manganese,cobalt,chromium and cadmium concentrations using atomic absorption spectrophotometer.Results:Mercury was not detected at all in the muscle,liver and gills of C.gariepinus.The mean±SD of metals in liver of C.gariepinus were:(0.080±0.014),(0.110±0.014),(6.480±1.279)and(0.295±0.021)mg/kg for Cd,Cr,Fe and Mn,respectively.In the gills,heavy metals values were:(0.065±0.021),(0.115±0.035),(5.843±0.558),and(0.345±0.007)mg/kg for Cd,Cr,Fe and Mn,respectively.In the muscles,heavy metals values were(0.045±0.021),(0.115±0.353),(5.150±1.075),and(0.187±0.045)mg/kg for Cd,Cr,Fe and Mn,respectively.The general trend of metals accumulation in tissues of C.gariepinus showed a decreasing trend of Fe>Mn>Cr>Cd.Also,the metal accumulation in the three tissues showed a decreasing trend of liver>gills>muscle.Conclusions:The metal concentrations in the muscle,gills and liver of C.gariepinus were all below the World Health Organization acceptable range,and as such fishery resources from Calabar River are safe for consumption.

Effects of pituitary extract,ovaprim,and bitter leaf(Vernonia amygdalina)on the histopathology of African catfish(Clarias gariepinus)

The development of aquaculture in Nigeria is constrained by the inadequate supply of high quality of fingerlings of African catfish(Clarias gariepinus).There are conflicting reports on the reproductive efficacy of Vernonia amygdalina when compared with the synthetic hormone Ovaprim(OV)and Pituitary Extract(PE)on C.gariepinus.The histopathology of select organs in catfish treated with generic Ovaprim(OV),Pituitary Extract(CPE),and aqueous extract of Vernonia amygdalina(VAE)were evaluated.Sixteen female C.gariepinus(average weight of 1 kg)wereevenly and randomly distributed to four groups.Fish in groups A,B,C,and D were injected intramuscularly with aqueous solutions of OV(0.5 mL/kg),PE(5 mg/kg),VAE(10 mg/kg),and distilled water(DW;0.5 ml),respectively.Histological examinations of the ovary,liver,kidney,and spleen were carried out.Histopathology revealed that OV-and PE-treated groups showed synchronous and synchronous ovarian development,vacuolar change of hepatocytes,thinning of hepatic cords,reduced renal haemopoietic compartments,tubular degeneration and necrosis,and decrease in splenic periarteriolar lymphoid sheaths(PALS).VAE-treated groups had asynchronous ovarian development with atretic ovarian follicles,widespread vacuolar change of hepatocytes,intact renal tubular and hemopoietic compartments,and preponderance of large and coalescing splenic PALS.We conclude that VAE is an ineffective spawning agent,especially when compared with OV and PE,as VAE could not induce synchronous gonadal development.However,VAE may have immunopotentiating,nephroprotective,and haemopoietic properties.

Influence of Lactobacillus plantarum supplemented diet on growth response,gut morphometry and microbial profile in gut of Clarias gariepinus fingerlings

Objective:To evaluate the influence of dietary inclusions of Lactobacillus plantarum(L.plantarum)on growth response,gut morphometry and intestinal microbial profile of Clarias gariepinus(C.gariepinus)fingerlings was carried out using a total of 150 C.gariepinus fingerlings(2.35±0.48 g/fish)by selecting at random into five treatments groups of 10 fish in 3 three replicates each.Methods:L.plantarum isolated from corn slurry was cultured using standard measures.Five isonitrogenous diets were prepared at 35%crude protein(T_(0),T_(1),T2,T_(3)and T_(4))with L.plantarum at inclusion rate of 0.0%,0.5%,1.0%,1.5%and 2.0%respectively.The fish were fed at 5%body weight per day for 12 weeks twice daily.Results:T_(4)recorded the highest mean weight gain and specific growth rate while the lowest was obtained in T_(1).T_(4)(1.97)when compared with other treatments had marginally lower feed conversion ratio.Absorptive area was most significantly higher in T_(3)and T_(4)group when compared to the control(T_(0))and other lower dietary probiotic inclusion groups.Cryptal depth was highest in T_(4)with significant difference which also gave the maximum enterobacteriaceae count while T_(0)recorded the least count.Conclusions:From these indications,L.plantarum fortified diets may enhance the growth of cultured C.gariepinus fingerlings at 2.0%inclusion rate as it was observed to improve body weight gain,feed conversion ratio with increment in the absorptive area and the microbial count in the gut.

The effects of on-farm produced feeds on growth, survival, yield and feed cost of juvenile African sharptooth catfish (Clarias gariepinus)

The culture of African sharptooth catfish(Clarias gariepinus)in most developing countries lacks suitable diets for semi-intensive production.The present study evaluated the growth performance,survival,nutrient utilization,hepatosomatic index(HSI),body composition,yield and feeding cost of African catfish fed on semi-intensive feeds 1(SMF1)and semi-intensive feed 2(SMF2)produced on-farm and an industrially manufactured(IM)feed as a control.Two hundred fish(14.95±0.24 g)were stocked in triplicate earthen ponds and fed the three diets at 5%of the body weight for eight weeks.The final weight,specific growth rate and yield of fish fed the SMF2 diet was significantly lower than SMF1 and IM diets.However,no significant differences were revelead in final weight,specific growth rate and yield between fish fed SMF1 and IM diets.The survival rate,feed conversion ratio and protein efficiency ratio of fish did not differ among the diets.Apparent net protein utilization was significantly higher on fish fed the SMF2 and SMF1 diets than IM diet.The HSI of fish fed the IM diet was significantly higher and the livers were yellow-coloured compared to smaller and brownish/reddish livers of fish fed the SMF1 and SMF2 diets.The fish fed the IM diet had statistically lower ash content than SMF1 diet.The incidence cost of fish fed the IM diet was 35%higher,while its profit index was 31%lower than fish fed the SMF1 and SMF2 diets.Taken together,African catfish farmers can reduce feed cost up to 30%by using on-farm produced feeds when formulated properly and blended without affecting fish growth performance,survival and yield while obtaining better protein retention and healthier fish.