Assessment of faecal contamination in selected concrete and earthen ponds stocked with Clarias gariepinus

Background This study was carried out to monitor the levels of faecal pollution markers in catfish (Clarias gariepinus) and their growing waters in selected earthen and concrete ponds. Water and catfish samples were collected weekly in the months of February, March, April, May, June and July, 2019. The concentrations of enteric bacteria in the water and catfish samples were determined using membrane filtration and pour plate methods, respectively. The rate of bioaccumulation of faecal indicator bacteria was obtained by dividing the log concentration of each organism in catfish by the corresponding log concentration in the growing waters. Result The concentration of faecal coliforms in catfish samples from concrete and earthen ponds ranged from 1.41 to 2.28 log10 CFU/100 ml and 1.3 to 2.47 log10 CFU/100 ml respectively and in growing waters from the concrete and earthen ponds; 1.43 to 2.41 log10 CFU/100 ml and 1.50 to 2.80 log10 CFU/100 ml respectively. Faecal coliforms exhibited positive relationships with alkalinity in water samples from the earthen (r = 0.61) and concrete ponds (r = 0.62). Salmonella and faecal coliforms had the highest and least bioaccumulation in catfish raised in earthen pond, respectively, whereas Salmonella and enterococci had the highest and least bioaccumulation in catfish raised in concrete pond, respectively. Faecal coliforms and E. coli had the highest and least counts in water samples from the earthen pond during the dry and wet months, Salmonella and E. coli had the highest and least counts in water samples from the concrete pond during the dry and wet months. Conclusion There were high levels of bacterial faecal pollution markers in water and C. gariepinus from the earthen and concrete ponds. Physicochemical characteristics of the water and seasonality played major roles in the rate of bioaccumulation of the faecal pollution markers in C. gariepinus raised in the earthen and concrete ponds.

Technical note: Growth performance evaluation of fingerlings from different lineages of Oreochromis niloticus farmed at sub-optimal temperature in earthen ponds / Nota técnica: Avaliação do desempenho de crescimento de alevinos de diferentes linhagens de Oreochromis niloticus cultivados em temperatura sub-ótima em viveiros escavados

O estudo avaliou o desempenho produtivo de duas linhagens de Oreochromis niloticus, GIFT (Genetically Improved Farmed Tilapia) e Chitralada (Thai), cultivadas em viveiros escavados com temperaturas sub-ótimas. Os viveiros foram povoados com densidade de dois peixes m-3 e três repetições para cada grupo. Inicialmente, os peixes foram alimentados com ração comercial (40% de proteína bruta). Após 30 dias, uma ração comercial com teor de 32% de proteína bruta foi utilizada até o final do estudo. Após 127 dias de cultivo, não foi observada diferença significativa nos índices produtivos entre as linhagens.

The visual characteristics and quality of cultured gilthead seabream (Sparus aurata) in earthen ponds and net cages in Turkey

The objective of this study is to investigate the quality differences and visual characteristics between cultured gilthead sea bream obtained from earthen ponds and net cage habitats. No significant differences from obtained in two different habitats are determined cultured gilthead sea bream in terms of chemical and microbiological quality. It has been determined that it is a safe food for consumption since it does not contain pathogenic microorganisms such as Escherichia coli and Salmonella spp. that negatively affect food safety. Visual quality differences are distinguished like the skin color, reddish color on the operculum cover, the head shape and the tail transparency from each other. Having unique sensorial characteristics fishes from two different habitats do offer valuable nutrient sources for consumers. Thanks to the controlled aquaculture conditions, safe production of cultured gilthead sea bream is carried out according to food safety in Turkey. Therefore owing to their delicious food source of cultured gilthead sea bream it is preferred for consumption in Turkey and all ower the world.

Culture Pond Influences the Growth and Survival of Clarias gariepinus Fingerlings reared in Poly and Monoculture

Monoculture is the rearing of single species of fish in a pond while polyculture is the farming of two or more species in the same physical space. This study aims to compare the growth parameters of Clarias gariepinus fingerlings in monoculture and polyculture, using concrete and earthen ponds in a randomized complete block design. The polyculture, comprised of Clarias gariepinus and Oreochromis niloticus. 480 fingerlings were used; the stocking density was 40fish in a 3x2x1.5m depth with initial weight (4.84±0.11547) for C. gariepinus in monoculture and 40 each in polyculture with an initial pooled weight of O. niloticus (50g) replicated thrice, it was fed for eight weeks with commercial feed (40% crude protein). Weekly, random sampling was done to measure the growth and adjust the feeding rate. The results revealed that polyculture has the best mean final weight (160.07±0.18559g) and weight gain of 155.29, while the highest total length (45.666±3.179) was recorded in monoculture for Clarias gariepinus reared in an earthen pond. The polyculture had the highest specific growth rate (2.46), Relative growth rate (246.49), and condition factor (0.184). There was a significant difference (P<0.05) in monoculture of both concrete and earthen ponds.

Fatty Acid Composition and Sensory Evaluation of African Catfish, Clarias gariepinus Reared under Different Culture Enclosures

This study was carried out to determine the fatty acid composition and sensory quality of Clarias gariepinus from different culture enclosures (plastic, sandcrete tanks and earthen ponds), at the Teaching and Research Farm of Department of Fisheries and Aquaculture Technology, Federal University of Technology, Akure, Ondo State, Nigeria. The comparative work was carried out to find out if habitat could influence the nutrient composition of the fish. Standard procedures were used in the analysis of tissue nutrient. Sensory evaluation study revealed differences in taste and texture indices considered for C. gariepinus reared in plastic, sandcrete tanks and earthen ponds (p<0.05). Fatty acid profiles of C. gariepinus were determined using Gas chromatography-mass spectrometry (GC-MS) method. The percentage of saturated and unsaturated fatty acids was higher (49.99%, 23.17%) in earthen pond cultured C. gariepinus than the plastic and sandcrete tanks. The study revealed that C. gariepinus raised in earthen pond possess fatty acid composition and sensory quality advantages over the plastic and sandcrete tanks. Keywords: Fatty acids, Sensory evaluation, Culture enclosures, Clarias gariepinus

Boosting fish production in Cameroon: Incorporated fish-rice farming versus earthen pond fish culture in Buea, Mount Cameroon region

Wetland incorporated fish-rice farming (FRF) is a possible solution to the problem of high costs of fish feeds in aquaculture in Cameroon. For 12 weeks, at the University of the Buea (UB) the growth of the fish, Clarias gariepinus in concurrent culture with rice (Oryza sativa, L.) in two rice plots (rice plot 1 and rice plot 2stocking sites) in the University of Buea wetland and in two earthen ponds (fish pond 1 and fish pond 2stocking sites) fed compounded diet at 5% body weight was investigated. Physico-chemical water quality parameters of all the fish culture sites were monitored. Mean fish weight gain was significantly higher (P<0.01) in the wetland rice plots (329.21±44.35g) than in the two earthen ponds (30.01±2.84g). Apart from low mean dissolved oxygen values in the rice plot 1 (3.14±1.19 mg/L) and rice plot 2 (2.18±0.23 mg/L), mean values for physico-chemical water quality parameters were within recommended ranges for C. gariepinus growth in all the four culture sites. This FRF experiment proved a better practice in fish growth than the conventional earthen pond culture in Buea, Cameroon. Its adoption by local fish farmers is recommended. Keywords: Wetland integrated fish-rice farming, C gariepinus, earthen pond culture, and fishpond.

Compensatory growth of tilapias (Oreochromis niloticus) reared in earthen ponds in Southern Brazil / Crescimento compensatório de tilápias (Oreochromis niloticus) cultivadas em viveiros escavados no Sul do Brasil

Tilapia fingerlings (0.5 ± 0.08g) were reared during the nursery phase in two different stocking densities (0.5 fish/m2 for control in a pond of 600m² and 75 fish/m2 for compensatory group in a cage of 4m²) for a period of 100 days. After this period, a 50-day trial study was performed with 43 juvelines of tilapia (Oreochromis niloticus) for each group (control 294 ± 24.43g and compensatory 99.33 ± 16.99g) stocked at the same density (0,28 fish/m2) in order to evaluate the compensatory growth in eathern ponds of 160m2 for each treatment. Throughout the experimental period the water quality was monitored and biometrics were performed to evaluate the zootechnical performance. The results revealed that the fishes of compensatory group presented higher specific growth rate compared to control, demonstrating a compensatory growth. At the end of the trial both treatments presented weight loss strongly influenced by temperature decrease. These results showed the compensatory growth of O. niloticus and the possibility to use this strategy (nursery in high density) contributing to ensure a successful production of O. niloticus in this region of the country.