Effect of Feeding on Fresh(wet)Housefly Maggots(Musca domestica)with or without Artificial Diet on Water Quality and Growth Rates of African Catfish(Clarias gariepinus Burchell,1822)Fry under Laboratory Conditions

No or little information on the use fresh(wet)housefly maggots(Musca domestica)in African catfish(Clarias gariepinus)fry feeding.Therefore,this study was conducted to investigate the effect of feeding on fresh(wet)housefly maggots with or without artificial diet on water quality,growth performance,survival percentage and feed utilization of African catfish fry under laboratory conditions.Housefly maggots produced from a mixture of poultry droppings and foods wastes,it was used to replace artificial feed at 0,50 and 100% levels.Catfish were fed artificial diet alone(Feed 1),fresh(wet)housefly maggots alone(Feed 2),and 50% fresh housefly maggots with 50% artificial diet(Feed 3)were prepared and tested on triplicate groups of African catfish fry(initial weight of 0.25±0.02 g)for 60 days.Results showed that final weight(g/fish)was significantly(P≤0.05)higher in fish fed on feed 3(6.03±0.08),followed by fish fed feed 2(4.62±0.27),followed by fish fed feed 1(3.15±0.68).Specific growth rate(%/day)was also significantly higher in fish fed on feed 3(5.31±0.10),followed by fish fed feed 2(4.86±0.03),followed by fish fed feed 1(4.18±0.24).The same trend was observed with total weight gain,percentage weight gain,daily growth rate and relative growth rate.Feed intake and protein intake were significantly(P≤0.05)higher in fish fed on feed 3 and fish fed on feed 2,followed by fish fed feed 1.While,feed conversion ratio(FCR)and protein efficiency ratio were not significantly(P>0.05),but the improvement in FCR recorded in catfish fry fed feed 3 and feed 2 under the experimental conditions.Survival percentage was within the range 55-75%,with insignificant differences(P>0.05)among treatments.The water quality parameters such as temperature,pH,dissolved oxygen,total ammonia,nitrite and nitrate were not significantly(P>0.05)between the treatments and were tolerable for Catfish culture.Accordingly,use of the 50% fresh(wet)housefly maggots with 50% artificial diet in African catfish fry feeding had positive effect on growth performance and reduce of the feed cost.

Bacterial diseases outbreak of African Catfish （Clarias gariepinus） from Manir River, Tcrengganu, Malaysia

A total of 190 bacterial isolates have been successfully isolated from 50 diseased African Catfish （C/arias gariepinus） namely; 70 isolates of Flavobacterium sp., 50 isolates of Aeromonas hydrophila, 30 isolates of Edwardsiella tarda and 20 isolate of each Hafnia alvei and Pseudomonas aeruginosa. This study was conducted to investigate bacteria that infected the broodstocks of African catfish cultured at Manir River, Terengganu as well as their antibiogram and Multiple Antibiotic Resistance （MAR） index. In the present study, antibiotic sensitivity and intermediary case were reported as 52.7% and 7.8%, respectively. Meanwhile, antibiotic case was recorded as 34.5%. The MAR index values obtained by each bacterial species was ranging from 0.24 to 0.52 whereas the average MAR index value was 0.39 which indicated that the cultured fish has been highly exposed to tested antibiotics.

Bioaccumulation of Zn in Muscle and Brain Tissues of the African Catfish—Clarias gariepinus

Increasing rate of consumption of the common African catfish, Clarias gariepinus, a popular delicacy in Delta State, Nigeria has raised worries about the safety of health of consumers in the face of perceived rising input of recalcitrant pollutants such as the heavy metals in aquatic habitats. This research investigated the presence and levels of Zn in muscle and brain tissues of C. gariepinus sourced from selected markets in Delta State. Replicate adult fish samples were obtained from seven market locations in Oleh, Asaba, Ekpan, Ogwashi-Ukwu, Okere, Abraka and Ughelli towns, labeled and taken to the laboratory in iced coolers. The presence and levels of the heavy metal were determined spectrophotometrically. Concentrations ranged from 0.015 - 0.19 (0.09 ± 0.02) mg/kg d.w. in muscle and 0.035 - 0.36 (0.16 ± 0.03) mg/kg d.w. in brain tissues, even as accumulation levels differed significantly (t = 0.005) between the tissues at p < 0.05. There was also significant locational heterogeneity in accumulations of the metal [F(100.97) > Fcrit(4.02)] at the 95% confidence limit;with least accumulation of 0.03 (±0.01) mg/kg d.w. recorded in fish samples obtained from Ughelli and maximum accumulation of 0.28 (±0.07) mg/kg d.w. recorded in those obtained from Oleh locations. However, levels were below the Food and Agricultural Organization and World Health Organization acceptable limits for Zn in edible fish. Results revealed that lipophilic brain tissues accumulated more heavy metal than muscle tissues. Since accumulation levels were low, they do not currently constitute public health risks to consumers in Delta State.

Sex Hormones Changes in Blood and Their Effect on Fecundity of African Catfish(Clarias gariepinus Burchell,1822)after Being Injected with Different Doses of Human Chorionic Gonadotropin(HCG)Hormone

This study was conducted to investigate the effect of different doses injection of human chorionic gonadotropin(HCG)hormone on fecundity and serum sex hormones(FSH,LH,estrogen(E2),progesterone(P4),testosterone(T))of African catfish(Clarias gariepinus).African catfish spawners were intermuscularly injected with different doses of HCG(500,1500,3000,6000 IU/kg female),and group is not injected as a control;males were injected at half the female dose.The results showed that,fish group injected by 6000 IU HCG/kg female had the highest gonadsomatic index,absolute fecundity and relative fecundity,while,the lowest value of absolute fecundity and relative fecundity were recorded with 500 IU HCG/kg female.The group injected with the highest amount of HCG(6000 IU/kg female)recorded the lowest value from egg diameter,while the highest egg diameter was observed in 500 IU HCG/kg female.In females,the group injected with 6000 IU HCG/kg female reflected the lowest level of FSH and the highest level of LH and the highest level of P4 compared to other treatments.Level of T recorded the highest level with 1500 IU HCG/kg female.The control group reflected the highest level of FSH and E2,while the control group reflected the lowest level of T and P4 level.In males,serum FSH,LH,P4 and E2 in male groups injected with HCG were relatively higher than those recorded in the control group.The highest level of T was recorded in treatment injected with the highest dose of HCG and decreased in other treatments until recorded the lowest level of T in the control group.It was observed,HCG hormone has successfully and accelerate induced spawning in African catfish(Clarias gariepinus)and increased in reproductive performance with the increase in HCG dosage and as compared to group not injected.

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.

Comparative Analysis of Amino Acid Composition in the Head, Muscle and Tail of Fresh African Cat Fish (Clarias gariepinus)

Consumption of seafood has increased globally over the past 50 years, from an average of 9.9 kg per capital in the 1960s to over 20 kg in 2016. In Nigeria, African catfish (Clarias gariepinus) has gained more attention in terms of farming and consumption compared to other seafood. This project was carried out to determine the level of amino acid composition in the head, muscle and tail of catfish so as to enlighten the public about their choice on the part of catfish to be eaten. Eight different sets of fresh catfish with a mean ± standard deviation of 15.6 kg ± 1.89, which were collected from a local fish pound in Ado-Ekiti, Nigeria, were used for the analysis. Extraction and evaluation of the amino acid composition were carried out using standard analytical techniques. The results obtained showed that high values of amino acids were observed in the fresh catfish (g/100g protein): 13.27 - 13.87 (Glu), 8.76 - 10.39 (Asp), 7.20 - 9.15 (Leu), 7.00 - 8.26 (Lys) and a low value in (Cys), 1.27 - 1.38. The total amino acids had a range of 89.16 - 92.12 g/100g. The coefficient of variation percent (CV %) for all the parameters determined were all generally low with values of 0.74 (observed for Ser) and 39.41 (observed for Pro). Total essential amino acid with histidine values ranged from 38.64 - 42.91 g/100g (CV % = 5.66). It was also observed that the concentrations (g/100g) of amino acids in the muscle of fresh catfish (92.12) are higher than that of the tail (91.98) and that of the head (89.16). There is no appreciable variation in the amino composition of the head, muscle and tail of catfish as the values observed were found to be statistically insignificant (p > 0.05). Therefore, it could be posited that the amino acid in the muscle, tail and head of African catfish would therefore be enough to prevent malnutrition in children and in adults who feed solely on any part of this fish as a main source of protein.

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.

摄食量对非洲胡子鲶及其杂交种生长的影响

本文系两种非洲胡子鲶Clariasgariepinus（C.g）和Heterobranchuslongifilis（H．l）以及它们的正反杂交种，在封闭式养殖系统下，不同摄食量对其生长影响的研究。40d的试验结果表明：（1）死亡率和体重差异系数只与交配亲鱼有关（p＜0．001），其中以C．g（F）×C．g（M）纯种最低；（2）各组在投食量（16～21）×（10－3m／m）0.8／d时，饲料系数均显最低。而C．g（F）×H.l（M）杂交种是4组中最低的；（3）各组可达到的最大摄食量存在显著差异（P＜0．001）。其中以C．g（F）×C．g（M）最高，C．g（F）×H．l（M）杂交种次之；（4）个体生长率和代谢体重相对生长率随着摄食量的增加而增加。其中以C．g（F）×C．g（M）最高，而C．g（F）×H．l（M）杂交种与之相比没有显著差异。C．g（F）×H．l（M）杂交种表现出一些良好的特性。

饵料中添加维生素C对非洲鲶鱼幼鱼生长和营养利用效率的影响(英文)

通过研究非洲鲶鱼(Clarias gariepinus)的生长和营养利用来探讨其维生素C的需求量。平均体重为6.02g±0.4g的鲶鱼幼鱼被放置在60cm×45cm×45cm的玻璃缸中,每缸10条鱼,每个处理设3个重复。5组饵料中粗蛋白的含量均为40%,并测定且其基础饲料中维生素C的含量。在第1、2、3、4和5组中,其饵料中维生素C多聚磷酸酯的添加量依次为0(对照)、50、100,150和200mg/kg。每天用这些饵料喂鱼两次,分别在格林尼治时间的9:00和16:00喂食。鲶鱼幼鱼每周称重一次,以便进行统计分析。通过其生长和营养利用效率进行生物学评估。结果表明,特定生长率、食物转换率、蛋白质效率和食物效率在所有组中彼此间都有显著差异。综合所有实验结果看,添加维生素C多聚磷酸酯150mg/kg的第4组,幼鱼的生长和营养利用效率最好。

Enzymatic and histopathologic biomarkers as indicators of aquatic pollution in fishes

In the present study we investigated the alteration in the activity of two metabolic enzymes [Glucose-6-Phosphate Dehydrogenase (G6PDH) and Lactate Dehydrogenase (LDH)] and the histological changes on liver and gills of the African catfish Clarias gariepinus collected from 6 sites along the river Nile, from its spring at Aswan to its estuary at Rosetta and Damietta branches. The results showed that the physical and chemical parameters of the water collected from Damietta and Rosetta branches were higher than those of the water collected from other sites. Remarkable alterations in the activity of the selected enzymes in the liver and muscles of the African catfish were detected. These alterations go in parallel with the elevation in the levels of chemical parameters detected in the water of Damietta and Rosetta branches as a result of pollution stress in these areas. The activity of G6PDH was significantly (p < 0.05) decreased from Aswan to Rosetta and Damietta recording the highest value at Rosetta followed by Damietta water. The activity of LDH showed a significant elevation (p < 0.05) in activity in the liver and muscles of fishes collected from Rosetta and Damietta branches comparing to other sites. These alterations in enzymatic activities were followed, in the present study, by the occurrence of histological lesions and clear damage in liver and gill tissues of the African catfish collected from the same sites. Thus we may conclude that, the altered activities of G6PDH and LDH could be useful biomarkers of water pollution. At the same time, histopathology provides a reliable, easily quantifiable index of low-level toxic stress to a broad range of environmental pollutants.

非洲鲶雨季与旱季的人工繁殖效果

为了解决尼日利亚水产养殖生产中鱼苗鱼种奇缺的难题,探索非洲鲶在雨季与旱季的繁殖规律,选用当地渔民池塘养殖的非洲鲶,采用人工催产繁殖的方法,按1∶2的雌雄比,在雨季(4-10月)催产14组,旱季(11月至次年3月)催产10组,比较不同季节对非洲鲶繁殖效果的影响。结果表明:1)平均每1 kg雌鱼的产卵数量:雨季达29 593粒,比旱季高89.06%,8月份的产卵效果最佳,达33 330粒;2)鱼苗孵化率:雨季为83.66%,比旱季高39.3%,孵化效果最好的是7月份,达89.25%;3)鱼苗培育成活率:雨季达44.81%,比旱季高21.02%,成活率最高的是9月份,达58.31%。在水温适宜的条件下,进行非洲鲶的周年人工催产繁殖是切实可行的。

Effect of partial and complete replacement of soybean with discarded cashew nut (Anacardium occidentale L) on liver and stomach histology of Clarias gariepinus (Burchell, 1822)

The need for replacement of highly priced soybean meal(SM)in fish diets with unconventional plant materials has become imperative for the sustainability of aquaculture production.This study addressed the effect of replacing SM with discarded cashew nut meal(DCNM)on the liver and stomach histology in African catfish(Clarias gariepinus).Total 90 juveniles(24.83±1.52 g)were fed DCNM based diets,inclusion level of 0,50%and 100%.Fish were fed twice daily(8:00 a.m.–4:00 p.m.)at 5%body weight for 56 days.The histology of liver and the stomach were assessed.Histo-morphological changes of the liver tissue were moderate at 100%DCNM fed fish compared to 50%DCNM and control(0 DCNM).Photomicrograph of stomach of 50%DCNM fed fish showed normal histo-morphological features,while moderate to severe histological distortions were observed in the stomach of 100%DCNM fed fish.The findings of the present study showed that partial(50%)replacement of SM with DCNM had no adverse nutritional consequence while total(100%)replacement of SM with DCNM in the diet of C.gariepinus resulted to moderate histological distortions of the liver and stomach.