Earthen Ponds Research Articles

Enhancing Aquaculture Productivity through Integrated Farming Systems: A Comparative Study of Fish-Pig and Fish-Duck Systems

Integrated farming systems involving fish-animal are of high relevance in current scenario. Studies like this asses the suitability of such systems in improving the aquaculture productivity and overall benefits to the ecosystem. It plays a crucial role in optimizing the use of small water resources in rural areas to enhance animal production. Given the potential of pig and duck manure as nutrient inputs in fish culture, a grow-out trial was conducted in a 0.1 ha earthen pond located in Elangitampatty, Kezhisenkattupatti, and Asakkattuppatti villages of Kollihills Taluk in Namakkal district, Tamil Nadu. The pond was stocked with four carp species: Catla, Rohu, Mrigal, and Grass carp in a ratio of 40:20:30:10 at a density of 7500 fish per hectare. Three treatments were employed: (1) Control (T0), where fish were fed with commercial feed, (2) Integrated fish-duck farming (T1), and (3) Integrated pig-fish farming (T2). In the control group (T0), fish were fed commercial fish feed (24% crude protein, 4 mm pellet size) at 4% of body weight, while in T1 and T2, fish received 50% of the commercial feed and were supplemented with duck and pig excreta, respectively. After an 8-month grow-out period, fish weights and total production in each group were recorded. Water quality parameters, such as pH, dissolved oxygen, free carbon dioxide, alkalinity, and hardness, were measured using standard methods (APHA, 2019). Results showed that pond fertilization with pig and duck excreta promoted the growth of algae, phytoplankton, and zooplankton, providing a natural food source for the fish. Total fish production was highest in the fish-pig integration system (T2), with a recorded yield of 4960.09 kg. Catla (Catla catla) had the highest individual species yield, with a total harvested weight of 2225.98 kg, followed by Grass carp (Ctenopharyngodon idella) at 1490.37 kg. The final average weight of Grass carp in T0, T1, and T2 was 1047 ± 13.27 g, 1151.10 ± 12.85 g, and 1490.37 ± 13.52 g, respectively. For Catla, the final average weight in T0, T1, and T2 was 910 ± 9.45 g, 960 ± 10.26 g, and 980 ± 12.20 g, respectively. Similarly, Rohu in T0, T1, and T2 weighed 850 ± 7.98 g, 900 ± 11.23 g, and 910 ± 11.16 g, respectively, while Mrigal in T0, T1, and T2 weighed 600 ± 6.04 g, 720 ± 8.50 g, and 730 ± 10.56 g, respectively. The results highlight that the fish-pig system outperformed the fish-duck system in terms of fish productivity, which may be due to the better nutrient composition in pig manure and the genetic potential of the fish species. An economic analysis revealed that the fish-pig integration system generated the highest net income (Rs. 555,353.90) and benefit-cost ratio (2.12), indicating that integrated fish-pig farming is more profitable than both fish-duck farming and the control group without integration.

Optimizing Eurasian Perch Production: Innovative Aquaculture in Earthen Ponds Using RAS and RAMPS-Economic Perspective.

Aquaculture in rural areas, carried out in accordance with current EU requirements, aims to contribute significantly to the conservation of the biodiversity of aquatic resources, the protection of which is a prerequisite for sustainable economic and social development. The objective of this study was to present the conceptual and technical framework and to analyze the costs and profitability of producing the consumer-attractive Eurasian perch (Perca fluviatilis L.) based on the untapped potential of hatchery infrastructure and dedicated earthen ponds for common carp (Cyprinus carpio L.) production. The experiments were conducted under Polish conditions, but the results/methods can be successfully applied in other countries, mainly in Central and Eastern Europe, where production in earthen ponds is the basis of aquaculture production. The analysis of the profitability of the venture shows that the cost structure was dominated by labor and feed inputs. Despite high variable costs, this type of production can be profitable and contribute to food security and economic development in line with the EU's Blue Growth Strategy. The article also analyzes the potential opportunities and risks of fish production based on the Recirculating Aquaculture System (RAS) and the Recirculating Aquaculture Multitrophic Pond System (RAMPS).

A multiple biomarker approach to understand the effects of microplastics on the health status of European seabass farmed in earthen ponds on the NE Atlantic coast

The occurrence of microplastics (MPs) in aquaculture environments is a growing concern due to their potential negative effects on fish health and, ultimately, on seafood safety. Earthen pond aquaculture, a prevalent aquaculture system worldwide, is typically located in coastal and estuarine areas thus vulnerable to MP contamination. The present study investigated the possible relation between MP levels of European seabass (Dicentrarchus labrax) farmed in an earthen pond and its health status. More precisely, two groups of fish were established based on the lowest and highest number of MPs found collectively in their gastrointestinal tract (GIT), liver, and dorsal muscle: fish with ≤2 MP/g and fish with ≥4 MP/g. The intestinal integrity and oxidative stress biomarkers in the liver and dorsal muscle were evaluated in the established groups. No significant differences in the biometric and organosomatic parameters between groups were observed. The results indicated a significant increase in the number of acid goblet cells (GC) in the rectum of fish with higher MP levels (p = 0.016). Increased acid GC number may constitute a first defence strategy against foreign particles to protect the intestinal epithelium. No significant differences in oxidative stress biomarkers between the two fish groups were observed, namely in the activity of superoxide dismutase, catalase, glutathione reductase, and glutathione S-transferase in the liver, or in lipid peroxidation levels in the liver and dorsal muscle. The overall results suggest that MP levels were possibly related to an intestinal response but its potential implications on the health status of pond-farmed seabass warrant further investigation. Monitoring MP occurrence across stages of aquaculture production could help to elucidate the potential threats of MPs to fish health.

Genetic Diversity Losses in Mantis Shrimp Oratosquilla oratoria Offspring Created for Supportive Releases Using an Ecological Breeding in Earthen Pond Method

ABSTRACTArtificial breeding of mantis shrimp Oratosquilla oratoria, using the ecological breeding in earthen pond (EBEP) method, has been carrying out from 2019, and the produced larvae have always been used for supportive breeding programs in Bohai Bay. To assess the degree of fidelity of enhancement programs used an EBEP method to native genetic pools, genetic diversity at 10 microsatellite loci was analyzed in three hatchery offspring populations, their wild parent stocks, and their wild contemporaneous offspring. Significant decrease in the almost genetic diversity parameters and highly significant differences in shannon's information index (decreasing by 22.54%–40.97%) and allelic richness (33.80%–46.87%) were observed between in hatchery populations. This further created relatively more genetic differentiation between the hatchery and wild population, as the pairwise Fst values and genetic distances showed. The mean pairwise relatedness coefficients showed higher values within hatchery populations and lower values within wild populations. Hatchery populations contained the fewest full‐sib families and offspring were extremely distributed in 10–11 full‐sib groups in each hatchery population. The relatively small number of actual spawning females and large variance in parental contribution to the next generation possibly causes allele reduction in the hatchery population, which in turn leads to a decrease in allelic diversity and an increase in genetic similarities among individuals. Promoting synchrony of ovarian development in females, providing good conditions for incubation and larvae culture and balancing the contributions of parents will be important in future breeding propagation.

Effect of ozone on Vibrio removal in a simulated earthen shrimp pond

ABSTRACT This study investigated the efficacy of ozone treatment on Vibrio pathogen removal within a simulated earthen shrimp pond, conducted in three phases. First, physical and chemical properties of the soil, alongside the Vibrio pathogen, were assessed. Results indicated neutral pH levels, high organic matter, and organic carbon content, with a Vibrio pathogen load of 1.0 ± 0.0 × 103 CFU/mg. Second, ozone treatment was applied, comparing its effectiveness in Vibrio pathogen control between treated and untreated soil sets. The treated set exhibited a significantly lower Vibrio pathogen load (6.00 ± 1.41 × 103 CFU/mg) compared to the untreated control (2.00 ± 2.12 × 105 CFU/mg), resulting in a 97.23% eradication efficiency. Concurrently, ammonia rates decreased with ozone, indicating potential benefits for shrimp aquaculture. Finally, ozone application in a simulated earthen pond over 45 days effectively controlled Vibrio pathogens. In the untreated soil set, Vibrio pathogen levels rose to 9.48 ± 1.73 × 105 CFU/mg, while in the ozone-treated, they ranged from 6.5 ± 2.12 × 103 to 1.25 ± 0.29 × 105 CFU/mg. Shrimp growth parameters, including average daily gain, survival rates, and feed conversion ratio, were compared between groups, suggesting ozone treatment's feasibility without adverse effects on shrimp growth. Water quality parameters remained within suitable ranges for shrimp cultivation. These findings highlight ozone's potential as an effective method for Vibrio pathogen control in shrimp aquaculture, with implications for industry sustainability and productivity.

Comparison of growth curves of the Pacific white shrimp, Penaeus vannamei Boone, 1931 (Decapoda, Penaeidae) reared in earthen ponds with three different water sources

Abstract The growth of the Pacific white shrimp, Penaeus vannamei was analysed with data from nine earthen ponds in three aquaculture farms located at the mouth of the Gulf of California in the state of Sinaloa, Mexico. Each farm has a different source of water supply: marine, estuarine-freshwater, and estuarine-hypersaline. Growth was estimated with a multi-model approach using five versions of the Schnute model. The parametrization was done with maximum likelihood as an objective function, and observing the variance criterion. The best model was selected via the Bayesian information criterion. The Schnute model reproduced the Von Bertalanffy model in the estuarine-freshwater conditions; the Logistic model in the estuarine-hypersaline situation; and the Gompertz model in the case of the marine water source. Differences in growth curves were corroborated via the Kimura ratio test. The difference in water quality was most evident in the factor salinity. The best performance was obtained with the estuarine-freshwater water source. The results support the hypothesis that postlarvae and juveniles exhibit better growth in brackish water than when supplied from a marine water source.

Effects of feeding regime on growth, production, and economics of Oreochromine cichlids (Oreochromis mossambicus) in earthen ponds of Bangladesh

The experiment was carried out to evaluate the effects of feeding frequency on the growth, production, and economic aspects of Oreochromine cichlids (Oreochromis mossambicus) in nine earthen ponds for 120 days. Three different feeding regimes (T1, T2, and T3) with three replications each were used. The stocking density was uniform across all treatments at 25,000 fish per hectare. The fish were fed a commercially available pelleted feed with the same feeding rate in all treatments, but the feeding frequency varied. The feeding rate was 10%, 8%, 7%, 6 %, 5%, and 4% which was consecutively adjusted after each fortnightly sampling and 3% for the last 4 weeks of the study period. Feeding frequencies were once a day for T1, twice a day for T2, and three times a day for T3. The average weight gain of Oreochromine cichlids in T3 (295±5 gm) was significantly higher (P<0.05) than those of T2 (240.67±6.66 gm) and T1 (217.17±7.64 gm). The survival rates were 95.20%, 96.99%, and 97.33% for T1, T2, and T3, respectively. The net production of fish in T3 (2882.00±62.00 kg/ha) was significantly higher (P<0.05) than in T2 (2413.00± kg/ha) and T1 (2223±30.55). Furthermore, the highest net return (USD 1163/ha with a cost-benefit ratio of 1.42) was achieved from T3, followed by T2 (USD 527/ha with a cost-benefit ratio of 1.19) and T1 (USD 270/ha with a cost-benefit ratio of 1.09). The results demonstrated that increasing the feeding frequency has positive effects on the growth and production of Oreochromine cichlids.

Length – Weight Relationship of Rohu (Labeo rohita) Advanced Fingerlings under Sodic Soil Condition

The present study was conducted at the Instructional Fish Farm, College of Fisheries, Acharya Narendra Deva University of Agriculture and Technology, Ayodhya, Uttar Pradesh, in earthen ponds (8m×8m×1m). The experiment for 90 days, using Labeo rohita advanced fingerlings (avg. wt. 30.0 ± 0.5g) under sodic soil conditions. Five treatments were taken in triplicate, with 50 fingerlings per pond. T1 served as the control with traditional feed only (MOC+RB in 1:1 ratio, 5% of total fish body weight). T2 and T3 were fertilized with cattle dung (20 and t ha−1 yr−1) respectively. T4 and T5 received poultry droppings (10 and 7.5 t ha−1 yr−1) respectively. Results showed negative allometric growth (b<3), indicating fish becoming slimmer with length increase. Final weight gain was highest in T4 (110.9±0.9 gm) and T2 (108.7±0.88 gm), and lowest in T1 (70.7±0.49 gm).

Water Quality Parameters of Sodic Soil Ponds Fertilized with Cattle Dung and Poultry Manure

A field experiment was conducted from August to November 2023 at the Instructional Fish Farm, College of Fisheries, Acharya Narendra Deva University of Agriculture & Technology, Kumarganj Ayodhya, Uttar Pradesh. The study aimed to assess water quality parameters. The experimental design included fifteen earthen ponds (8m × 8m × 1m), divided into five treatments with three replicates each. The treatments were as follows: (T1) control with pond bottom soil base, (T2) pond bottom soil with cattle dung at 20 t/ha, (T3) pond bottom soil with cattle dung at 15 t/ha, (T4) pond bottom soil with poultry droppings at 10 t/ha, and (T5) pond bottom soil with poultry droppings at 7.5 t/ha. Over the 90-day experimental period each pond evaluated the effects of cattle dung andpoultry droppings on water quality parameter. Results demonstrated that the treatment with poultry droppings at 10 t/ha (T4) significantly enhanced water quality, proving to be superior to treatments with cattle dung, followed by treatment T2 (20 t/ha cattle dung).

Evaluation of Tidal Energy Potential Using a Two-Way Tidal Energy Model

Tidal energy is a renewable energy source that provides sustainable energy through the utilization of tidal differences, making it a very promising option. This study examines a more effective tidal energy reservoir model by building a 1:100 scale prototype in the laboratory with several predetermined variations, namely an earthen pond (100, 80, and 60 cm), and flow holes (1.5, 1, and 0.5 cm) with initial tidal height differences of 10 cm, 15 cm, and 20 cm. The model uses a 6-hour time period, which corresponds to a semidiurnal tidal model. The results showed that the highest energy output was 281.84 kWh, achieved with a 1.5 cm flow hole, 20 cm tidal height difference for the initial condition, and 80 cm pond width. For a 1 cm flow hole, the outputs were 1774.8 kWh and 1803.78 kWh for 15 cm and 20 cm tidal height difference for the initial condition with a pond width of 100 cm. Meanwhile, the 0.5 cm flow hole produces potential energy outputs of 2623.8 kWh and 2611.4 kWh for different tidal heights of 15 cm and 20 cm for the initial condition with a pond width of 100 cm. Better model performance can be connected to a mini generator to validate the energy generated from the designed prototype model. Doi: 10.28991/CEJ-2024-010-09-016 Full Text: PDF

Fish production, water quality, and the role of nitrification as an ammonia removal process in intensively aerated hybrid catfish ponds

AbstractSix 0.1‐ha earthen ponds with 45 kW/ha of aeration capacity were stocked with hybrid catfish (Ictalurus punctatus x I. furcatus) ranging from 15,000 to 90,000 fish ha−1 in 15,000 fish ha−1 increments to analyze the effect of nitrogen loading on ammonia accumulation and fish production. Minimum dissolved oxygen (DO) concentration was maintained above 3.0 mg O2 L−1 to prevent hypoxia‐induced appetite reduction. Stocking density did not impact survival but decreased average fish harvest weight and increased food conversion ratio (FCR). Gross production increased with stocking density and ranged from 7249 to 35,674 kg ha−1. Average total (TAN) and un‐ionized ammonia (NH3) were not different among stocking densities despite greater nitrogen inputs in ponds with higher feeding rates. Nitrite () and nitrate () concentrations were significantly higher in ponds with higher stocking densities, suggesting that nitrification increased with nitrogen loading. Phytoplankton assimilation of ammonia is the primary ammonia removal process in traditional catfish ponds with modest fish densities and feeding rates. However, in intensively aerated ponds with high feeding rates, nitrification can become an important process for ammonia removal. These data indicate that small earthen hybrid catfish ponds with high aeration capacities can increase catfish production without ammonia accumulating.

Effect of Crossbreeding on Fecundity, Growth Performance, and Heterosis of Black Tilapia, Red Tilapia, and Mozambique Tilapia Reared in Earthen Ponds in West Java, Indonesia

Graphical Abstract Highlight Research The crossbred performance of the four tilapia strains showed diverse heterosis values, with some being better, worse, or the same as their parents. Crossbred of black tilapia produced the best growth and fecundity performance. A hybrid of Mozambique tilapia and black tilapia showed the highest mid-parent heterosis value on growth traits but produced negative heterosis on fecundity, biomass, and survival traits. Crossbred of black tilapia and Mozambique tilapia have the potential to be used as candidates for cultivation and performance improvement through selection, although there are depressions and crossover advantages that are not prominent. Abstract Increased tilapia production is challenged by genetic decline. Hybridization efforts for performance improvement through a selection of the best parent and strain pairs were a promising option. The objective of this study was to evaluate the crossing of black tilapia, red tilapia, and Mozambique tilapia against the performance of fecundity, growth, and survival and estimate the value of heterosis. The experimental design used a completely randomized design with 3 replications with the treatment of different populations of crosses. The rearing activities were carried out in earthen ponds for 150 days with a stocking density of 10 fish/m2. The parameters observed included egg fecundity, growth, survival, and the value of heterosis. The results showed that the fecundity and growth values of crossbred black tilapia were significantly higher than others (p<0.05). The highest survival rate was shown by crossing pure strains of red tilapia. The hybrid of Mozambique tilapia and black tilapia (♀ MJ x ♂ NW) showed the highest mid-parent heterosis value on growth characters but produced negative heterosis on characters, fecundity, biomass, and survival. Overall, the crossbred of black tilapia (♀BS x ♂ NW) performed better than the inbred strains, with positive mid-parent heterosis in all characters measured. These results indicate that crossbreeding has the potential to be used as a candidate for cultivation and performance improvement through selection, although there were depressions, and the superiority of the crosses was not prominent.

Macroinvertebrates Associated with Macroalgae within Integrated Multi-Trophic Aquaculture (IMTA) in Earthen Ponds: Potential for Accessory Production

The present work aims to evaluate the macroinvertebrate community associated with macroalgae in earthen pond systems to better understand their potential in detritus recycling and as an accessory production. Sampling took place on the settling pond of an aquaculture research station, where macroalgae permanently occurred at high densities. The results suggest differentiation between seasons but not between sites within the settling pond. Seasonal variation was observable in terms of macroinvertebrate density, biomass, and diversity. Two non-indigenous species of invertebrates were found, the crustaceans Grandidierella japonica and Paracerceis sculpta Amphipods were the most abundant group, and their high nutritional value can be exploited. Detritus and the epiphyte layer are the main food items for the invertebrates, reinforcing the advantages of these organisms being present to enhance the recycling of excess detritus and to transfer organic matter to upper trophic levels. These species, naturally present in aquaculture facilities, can improve the water quality and increase the variability of food nutrients for reared species.

Improper dietary protein to carbohydrate ratio causes abnormal visceral fat deposition, hampering gonadal development and breeding performance in Labeo Catla female

The availability of balanced diet is critical for reproductive success in fish. A feeding trial on Labeo catla females was carried out in earthen pond to assess the effect of different dietary protein to carbohydrate ratio on gonad maturation and breeding performance. Three feed D-I (Feed-I), D-II (Feed-II) and D-III (Feed-III) were formulated with varying ratio of Ground Nut Oil Cake (GNOC) and rice bran (2:1, 1:1 and 1:2) and fed for 120 days. To assess the gonad maturation events, GSI VSI, breeding, fatty acid analysis, sex hormone profiling, cholesterol, triglyceride and histological examinations were conducted. Fish groups fed with D-III exhibited the highest VSI and visceral fat (VF) deposition, followed by those fed with D-I, whereas groups fed with D-II showed significantly lower levels (P<0.05). The result of GSI was completely opposite to values of VSI. Ovarian histology showed less number of mature oocytes in D-I & D-III treatments and more mature oocytes in D-II. Breeding results showed that fishes fed with D-I and D-III hampered gonad maturation whereas fish fed with D-II responded towards spawning, fertilization, and hatching. Increased levels of testosterone, estradiol, and vitellogenin (Vtg) were observed in the D-II fed group whereas increased level of progesterone was observed in D-I fed group followed by D-II and D-III. Serum cholesterol was higher in the D-III and D-I group. Visceral fat accumulation prior to ovarian maturation is a normal phenomenon in this species which serves as a lipid reservoir required for the later transfer to the gonad as yolk or is utilized as an energy source for gonad maturation. However higher level of protein or carbohydrate in the diet disrupted normal gonad maturation and lead to abnormal visceral fat accumulation, sex steroid level, failure in spawning response and seed production.

Comparative Study of Hydrobiological Parameters Between Earthen and High-Density Polyethylene (HDPE) Brackishwater Shrimp Ponds in Ratnagiri, Maharashtra

The current study was carried out to compare the hydrobiological characteristics of a selected shrimp farm in district Ratnagiri taking pond size, stocking density and culture practices into consideration. For sampling, four earthen and four high-density polyethylene (HDPE) ponds were chosen. Most of the water parameters showed significant difference with respect to different types of ponds (earthen and HDPE) viz. temperature, pH, salinity, dissolved oxygen, alkalinity and net primary productivity (NPP) of both crops (p&lt;0.05). First crop showed significant difference among all water parameters except biochemical oxygen demand (p&lt;0.05). Second crop (January-May) showed significant difference (p&lt;0.05) among all parameters except hardness, ammonia, nitrite, gross primary productivity (GPP) and community respiration (CR). Phytoplankton showed significant difference (p&lt;0.05) with respect to different types of ponds for both crops and zooplankton showed significant differences (p&lt;0.05) only during first crop. Results indicated that high-density polyethylene (HDPE) ponds have greater consistency in water quality characteristics than earthen ponds, which could contribute to enhanced shrimp growth and survival.

Effects of minimum dissolved oxygen setpoints for aeration in semi-intensive pond production of Pacific white shrimp (Litopenaeus vannamei)

Aeration is considered one of the most critical factors in shrimp farming as it affects the metabolism of shrimp and other living organisms within a pond. Maintenance of proper dissolved oxygen (DO) concentrations is critical, as low DO can cause stress, lower resistance to disease, and inhibit growth. Although the effects of single, short-term hypoxia events have been widely studied, little to no research has examined effects of repeated exposure to hypoxia during multiple diurnal cycles that shrimp may experience in aquaculture ponds. Even though the concept is simple, proper DO management is not simple. It is dependent on numerous factors and often based on anecdotal recommendations. The present trial was conducted to help elucidate the effects of DO management strategies on shrimp performance. The trial examined the effects of three different DO set points for automatic aeration on shrimp production and water quality parameters in earthen ponds. In sixteen earthen ponds (0.1 ha), juvenile Pacific white shrimp (⁓0.030 g) were stocked at a density of 25ind/m2. Minimal DO setpoints that activated automatic aeration in each of the treatments were 2.5, 3.5, and 4.5 mg O2/L, respectively. Shrimp were fed using the AQ1 passive acoustic monitoring system that was set to not feed while DO was below the threshold of a given treatment. Each of the treatments was applied to 5 ponds, except for treatment 1 (2.5 mg/L) which was applied 6 ponds as it was considered of higher risk. Shrimp growth performance and water quality indicators were monitored weekly. At the end of the 79–81-day trial, results showed that different aeration control treatments had no significant effect in terms of growth performance, feed inputs or productivity parameters. The final weight of the shrimp ranged between 33.3 and 33.6 g, with average final yields of 7500–8500 kg per ha. Nonetheless, mean electrical costs differed significantly between treatments, with higher DO setpoints treatments exhibiting a higher aeration cost with no discernible benefit. Water quality parameters showed no significant difference, except for morning and afternoon DO concentrations.

Lactococcus lactis MA5 is a potential autochthonous probiotic for nutrient digestibility enhancement and bacterial pathogen inhibition in hybrid catfish (Ictalurus punctatus × I. furcatus).

With the emergence of diseases, the U.S. catfish industry is under challenge. Current trends prefer autochthonous bacteria as potential probiotic candidates owing to their adaptability and capacity to effectively colonize the host's intestine, which can enhance production performance and bolster disease resistance. The objective of this study was to isolate an autochthonous bacterium as probiotic for hybrid catfish. Initially, an analysis of the intestinal microbiota of hybrid catfish reared in earthen ponds was conducted for subsequent probiotic development. Twenty lactic acid bacteria were isolated from the digesta of overperforming catfish, and most of the candidates demonstrated probiotic traits, including proteolytic and lipolytic abilities; antagonistic inhibition of catfish enteric bacterial pathogens, negative haemolytic activity and antibiotic susceptibility. Subsequent to this screening process, an isolate of Lactococcus lactis (MA5) was deemed the most promising probiotic candidate. In silico analyses were conducted, and several potential probiotic functions were predicted, including essential amino acids and vitamin synthesis. Moreover, genes for three bacteriocins, lactococcin A, enterolysin A and sactipeptide BmbF, were identified. Lastly, various protectant media for lyophilization of MA5 were assessed. These findings suggest that Lactococcus lactis MA5 can be an autochthonous probiotic from hybrid catfish, holding promise to be further tested in feeding trials.

Rearing of European catfish (Silurus glanis L.) in earthen ponds in polyculture with common carp larvae (Cyprinus carpio L.)

The aim of the present study is the production of stocking material of European catfish (Silurus glanis L.) using common carp larvae (Cyprinus carpio L.) as natural food source. The experiment was carried out in two earthen ponds (№18 and №19). The stocking material was produced through semi-artificial reproduction of European catfish and natural reproduction of common carp in two stages. The main aquaculture production indicators of the stocking material of European catfish and common carp were calculated: growth (WG, g), survival (%), total yield (kg) and average yield (kg/1000 m2). The obtained results show that the growth of European catfish in pond №19 is 69.67 g, while in pond №18 it is 58.91 g. Also, the survival rate in pond №19 is 2.8 times higher than in pond №18. After analyzing the obtained results, it can be concluded that the production indicators of the European catfish stocking material are higher in experimental pond №19.

Evaluating the growth performance of all male sex reversal and mixed ser tilapia (Oreochromis niloticus) cultured in earthen ponds in Binh Phuo province, Vietnam

The study was conducted to evaluate the growth performance, survival rate and yield of all male sex reversed and mixed sex Nile tilapia (Oreochromis niloticus) cultured in earthen ponds for 180 days. The reversed sex and mixed sex fingerlings (mean weight 7.43 ± 0.35 g) was randomly stocked in six earthen ponds (1,000 m2/pond). The stocking density maintained was 5 fish/m2. The stocked fish were fed a commercial pellet feed containing 35% crude protein. The feeding rate was adjusted according the size of fish, 5% at the beginning to 3% at harvest. Water environment parameters including dissolved oxygen (DO) (4.3 ± 0.8 mg/L), temperature (30 ± 0.7°C), NH3 (0.18 ± 0.2 mg/L), and pH (6.9 ± 0.5) were always within the appropriate range for the normal growth and development of tilapia. The growth rate of sex reversed tilapia was significantly higher (P &lt; 0.05) than that of mixed tilapia throughout the experiment. The harvest weight and length of reversed sex tilapia were 410.5 ± 5.15 g and 25.48 ± 0.48 cm, respectively, and were significantly higher than that of mixed sex tilapia (P &lt; 0.05). The survival rates and feed conversion ratio (FCR) of mono and mixed sex were 90.1% and 89.9%, respectively, but no significant differences were observed (P &gt; 0.05). The relationship of fish lengths and weights expressed by power function revealed that the slope of the length weight regression lines was normal for reversed sex (2.72) and mixed sex Tilapia (2.93) with the high correlation coefficient (&gt; 0.9). The findings of this study demonstrate that reversed sex tilapia has better growth performance compared to mixed sex tilapia. Therefore, reversed sex fingerlings should be used in commercial farming to increase tilapia production.

Investigation of small-scale farming status of Tire track eel (Mastacembelus favus) in the Mekong Delta, Vietnam

Tire track eel (Mastacembelus favus) is an economically important freshwater fish in the Mekong Delta. However, there is a lack of academic information about the current farming status, feed, and feeding related to this species in the region. Therefore, a field survey of small scale farming of tire track eel was conducted in An Giang, Dong Thap, Hau Giang and Kien Giang provinces of Vietnam. The objective of the survey was to determine the current farming practices information on households, especially the feed and feeding status of tire track eel in order to improve and develop a suitable feed for this fish in the future. The results showed that most of the small-scale farmers cultured fish in earthen ponds with or without plastic liners. Tire track eels were fed with feeds of other species and typically fed 3 - 5 times/d during the fingerling stage, and twice per day during the grow-out period. In terms of feed ingredients, crude protein contents in the feeds were 39.5 - 45.5% while crude lipid contents were 7.7 - 12.7%. Feed conversion ratios of tire track eels were 2 - 5. The farming periods of fish were 11.8 - 14 months when the fish reached the harvesting sizes of 318.2 - 421.4 g/fish, with the survival rates of 40 - 80%. It took 2.5 months to cultivate the fingerling stage (around 3 g/fish) from the fry with the survival rate of 55.7%. It was reported that this species was raised with a simple technique and got less illness compared to other fish species. However, the main reason of fish deaths during farming period related to management factors such as poor water quality due to decomposition of uneaten feed in water or lacks of dissolved oxygen due to high stocking density or power supply failures.