Net Fish Yield Research Articles

Ecosystem-based fishery enhancement through pen culture of Indian major carp Labeo catla in a tropical floodplain wetland of North Eastern Region, India, during COVID pandemic.

The present study was conducted with the objective of developing ecologically and economically feasible pen culture protocols for Labeo catla as an alternate income source for wetland fishers in the context of the COVID-19 pandemic. Yearlings of L. catla (12.33 ± 1.99 cm mean total length and 26.05 ± 6.57 g mean weight) were reared in HDPE pens (500 m2 area each) at three different stocking densities of 3 (SD3), 6 (SD6) and 9 (SD9) no. m-2 in triplicates. Fishes were fed with floating pelleted feed containing 28% crude protein and 5% crude lipid two times daily at 1.5-3% of body weight. During the culture period, fish grew from 26.05 ± 6.57 to 434.61 ± 30.63 g, 306.13 ± 10.68 g and 221.13 ± 14.92 g, respectively, at stocking densities of 3, 6 and 9 no. m-2 respectively. Weight gain percentage and specific growth rate declined with increase in stocking density. Gross fish yield increased with increase in stocking density and was highest at SD9 (657.92 ± 53.55 kg pen-1), while net fish yield increased initially from SD3 to SD6 (594.31 ± 29.72 kg pen-1) and then declined with further increase in stocking density. Important water quality parameters influencing fish growth were measured, and significant difference (p > 0.05) was not observed between treatments (inside pens) and reference site (outside pen at 10-m distance). Weight gain was positively correlated (p < 0.05) to water temperature (r = 0.989) and total phosphorus (r = 0.81). Benefit cost ratio and net return was highest at SD3 (1.61; US $518.88, respectively). Stocking density of 3 no. m-2 can be considered economically feasible for table fish production of L. catla in pens. Post pen culture, monthly income of fishers increased by 10.76-179.11%, with a mean increase of 90.57%, compared to the period of first COVID-19 wave in India. The present findings can provide an impetus for effective utilization of pen enclosures for income generation and livelihood enhancement of small-scale wetland fishers during pandemic.

Performance of phytase-treated fishmeal-free and all-plant protein diets in pond production of market sized hybrid striped bass

We determined if ideal protein (IP) fishmeal-free (FMF) or all-plant protein (PP) diets of available ingredients satisfied production needs of hybrid striped bass (HSB; Morone chrysops x M. saxatilis) grown to market size in ponds managed according to industry practices, and if phytase (Phy) superdosing (20,000 FTUs) could alleviate inorganic phosphorus supplementation. An off-the-shelf commercial feed (COM), an IP control diet containing 16% fishmeal (FM), and four IP test diets with or without phytase superdosing (FMF, FMF + Phy, PP, PP + Phy) were evaluated. Inorganic phosphorus was excluded from phytase treated diets. Hybrid striped bass (averaging 344 g/fish) were stocked (5187 fish/ha) in 4 ponds/diet (0.1 ha) and grown for 5.5 months. Most responses of the five ideal protein diets did not differ significantly (P > 0.1) from the COM. Only net fish yield, weight gain, and FCR of the PP diet were less than those of the COM diet. Fish fed FMF and FMF + Phy diets had higher fish yields, mean weights, and gains than PP and PP + Phy diets. FMF ponds had fewer than expected large (907–1134 g) and more jumbo (>1135 g) fish and FMF + Phy ponds had fewer medium (680–906 g) and more large fish. PP ponds had fewer than expected jumbo fish. The COM diet resulted in larger livers (HSI), lower muscle ratio, but less feed phosphorus added to ponds compared to the FM diet. Absence of differences for other responses confirms the FM diet is a valid proxy for the COM diet. Phytase increased energy and protein retention of the PP diet but not the FMF diet. FM can be replaced with animal and/or plant proteins exclusively without major reductions in hybrid striped bass performance. The PP diet likely requires optimization of Met and branched chain amino acid levels to improve performance. Inorganic phosphorus can be replaced by diet phytase top-coating and judicious inclusion of phytate‑phosphorus without negative impact on HSB production. Phytase superdosing of the FMF and PP diets did not improve production variables but did improve mineral retentions, more so for the PP diet. Phytase superdosing reduced feed phosphorus fed by 60% and pond phosphorus loading by 40% but requires optimization of inclusion levels and economic evaluation before recommendation.

Evaluation of gardi bangana dero and sahar tor putitora with rohu labeo rohita and Naini cirrhinus mrigala in poly culture at different stocking combinations

Conventional multispecies poly culture with compatible native species intercrop augments optimum utilization of the ecological niches in the pond ecosystem, diversity conservation, food value, and poverty alleviation potential through the direct involvement of rural people. Given the conservational value and the aquaculture potential of several indigenous species, Gardi Bangana dero and Sahar Tor putitora have been identified as important food fish. Rohu Labeo rohita and Naini Cirrhinus mrigala are two other native fishes that fetch a very high market price and are of high cultural value. A polyculture experiment was carried out on the Rohu, Naini, Gardi, and Sahar with the objectives to evaluate the optimum stocking density in terms of average body weight, specific growth rate, and total fish production of these fishes for nine months. Results showed that the final body weight of Rohu, Naini, Gardi were high in respective major poly culture systems, but Sahar was high in Naini major system. In case of survival, all fish species had high survival rate in Naini major system. Also, net fish yield of Rohu was observed significantly higher in Rohu major pol yculture system than in Naini major and Gardi major poly culture systems but not with control poly culture systems. Whereas, parameters of Naini, Gardi and Sahar observed similar in all poly culture systems. Apparent Feed Conversion Ratio was found higher in Gardi major poly culture system than others. Thus, for getting optimal stocking density, Naini polyculture system with supplementary feed is recommended.

Growth performance of different fish species during dry period in Chitwan, Nepal

In order to assess the growth and yield of different fish species during dry period, an experiment was conducted in the Aquaculture Farm of Agriculture and Forestry University, Rampur, Chitwan from 1 April to 10 July, 2021. The experiment included three treatments: T1 (Carp polyculture), T2 (Common carp Cyprinus carpio monoculture) and T3 (Nile tilapia Oreochromis niloticus monoculture), each with three replications. Silver carp (Hypophthalmichthys molitrix 7%), Bighead carp (Aristichthys nobilis 20%), Grass carp (Ctenopharyngodon idella 13%), Rohu (Labeo rohita 30%), Mrigal (Cirrhinus mrigala 10%) and Common carp (20%) were stocked at densities of 1,400, 4,000, 2,600, 4,000, 6,000 and 2,000 fish/ha, respectively. Stocking density of Common carp and Nile tilapia was 20,000 fish/ha. Fish were fed with sinking pellet (28% crude protein) at the rate of 3% of body weight. Gross and net fish yield was significantly higher in T3 (89.89±0.67 t/ha/yr,16±0.25 t/ha/ yr) than in T2 (4.88±0.38 t/ha/yr, 4.05±0.35 t/ha/yr) due to higher (p&lt;0.05) survival in T3 (72.5±11.3 %) than in T2 (40.6±4.5 %). Gross margin was significantly higher in T3 (1,257,482±186,600 NRs./ha/yr) than in T2 (434,250±124,753 NRs./ha/yr). Based on higher survival, yield and gross margin, Nile tilapia monoculture is suitable for dry season.

Effectiveness of different measures to control red bloom in carp ponds

Red blooms caused by Euglena sanguinea (Ehrenberg, 1832) might cause severe depletion of dissolved oxygen significantly in the pond. An experiment was conducted to assess the effects of measures for controlling E. sanguinea on water quality, growth and yield of carp polyculture. The experiment included four treatments: without mitigation measure (T1), skimming using net skimmer (T2), fertilization with urea and diammonium phosphate (T3) and liming using agriculture lime (T4) with three replications. The experiment was carried out for 120 days. The results showed that abundance of E. sanguinea was significantly lower (p &lt; 0.05) in urea and diammonium phosphate treated ponds (270 ± 10 cells L-1) than control ponds (1650 ± 90 cells L-1). Water quality parameter such as nitrite, total nitrogen and total phosphorus were significantly (p &lt; 0.05) higher in control ponds (T1) than in treatment ponds. The net fish yield of rohu was significantly higher (0.19 ± 0.0 t ha-1) in T3 ponds than T2 ponds (0.07 ± 0.0 t ha-1). The present experiment effectively controlled abundance of E. sanguinea but admixture of urea and diammonium phosphate application appeared to be better control measures because dissolved oxygen content was at acceptable level in the ponds.

On-Farm Assessment of Different Fingerling Sizes of Nile Tilapia (Oreochromis niloticus) on Growth Performance, Survival and Yield

Rapidly increasing hatchery-raised Nile tilapia (Oreochromis niloticus) in most developing countries lack informed recommended fingerling weight for stocking in semi-intensive grow-out ponds. The current study assessed the growth performance, survival and productivity of all-male Nile tilapia fingerlings of 0.2 g, 1 g, and 5 g in an on‐farm experiment. The final mean weight of fingerlings stocked at size 5 g was significantly higher (113.80±4.21 g) (P&lt;0.05) compared to the 0.2 g (36.99±1.14 g) and 1g (91.93±5.59 g) fingerling sizes. The mean daily weight gain was highest in 5 g stocked fingerlings (0.91±0.04 g day -1) resulting in significant differences in the final mean weight. The coefficient of correlation between fish body length and weight was high and positive ranging (R=0.95-0.98). Significantly low percent survival was recorded in 0.2 g stocked fingerlings (64.4 3±1.93%). The net annual fish yield (NAY) and profit index (PI) were significantly lower at the 0.2 g. The highest NAY and PI were recorded in the 5 g stocked fingerlings (8.59±0.09 tons ha-1 year-1 and 6.6±2.08), respectively. Thus, with appropriate Nile tilapia fingerling weight at stocking, fish farmers can maximize fish growth, yield and profits.

Nutrient loading and farm characteristics of giant gourami fish aquaculture systems in Lake Maninjau, Indonesia: basic knowledge of production performance

Background Aquaculture systems for giant gourami, Osphronemus goramy Lacepède (1801), have significantly improved fish production yields and food security in Indonesia. However, these systems also cause serious problems in terms of eutrophication in waterbodies. This study analysed the nutrient loading and farm characteristics of giant gourami in floating cages in Lake Maninjau. Method A total of 20 floating cages were used to record these nutrients in feed supply, female and male juvenile fish, dead fish and harvested fish to estimate nutrient loading. Data on the harvested fish, production cycle, stock number and cage capacity were used to estimate the stocking density, feeding rate, feed efficiency, and net fish yield, and the relationship between feed supply and nutrient loading and farm characteristics was analysed by least squares regression methods. Results A total of 20 floating cages released nutrients into waterbodies at an average rate of 236.27±60.44 kg/cycle for C, 84.52±20.86 kg/cycle for N and 8.70±3.63 kg/cycle for P. On average, fish production for each floating cage (±SD) was 1226±282 kg wet weight/cycle, and the net fish yield was 12.63±2.82 kg/m3/cycle. Survival rates ranged from 86.33 to 95.27%/cycle. The production cycles varied from 160 to 175 days with feed conversion ratios between 1.60 and 1.75, feed conversion efficiencies were between 0.58 and 0.63. The production parameters that had strong relationships with the net fish yield were feed supply (r2=0.960), stocking rates (r2=0.924) and feeding rates (r2=0.961). In contrast, the length of the production cycle was not strongly related to the net fish yield (r2=0.187). Conclusion Nutrient loading from the supplied feed was greater than that from the harvested fish, juvenile fish and dead fish. Increasing the net fish yield in floating cages was better predicted by the stocking densities and feeding levels than by the other factors.

Nutrient loading and farm characteristics of giant gourami fish aquaculture systems in Lake Maninjau, Indonesia: basic knowledge of production performance

Background Aquaculture systems for giant gourami, Osphronemus goramy Lacepède (1801), have significantly improved fish production yields and food security in Indonesia. However, these systems also cause serious problems in terms of eutrophication in waterbodies. This study analysed the nutrient loading and farm characteristics of giant gourami in floating cages in Lake Maninjau. Method A total of 20 floating cages were used to record these nutrients in feed supply, female and male juvenile fish, dead fish and harvested fish to estimate nutrient loading. Data on the harvested fish, production cycle, stock number and cage capacity were used to estimate the stocking density, feeding rate, feed efficiency, and net fish yield, and the relationship between feed supply and nutrient loading and farm characteristics was analysed by least squares regression methods. Results A total of 20 floating cages released nutrients into waterbodies at an average rate of 236.27±60.44 kg/cycle for C, 84.52±20.86 kg/cycle for N and 8.70±3.63 kg/cycle for P. On average, fish production for each floating cage (±SD) was 1226±282 kg wet weight/cycle, and the net fish yield was 12.63±2.82 kg/m 3/cycle. Survival rates ranged from 86.33 to 95.27%/cycle. The production cycles varied from 160 to 175 days with feed conversion ratios between 1.60 and 1.75, feed conversion efficiencies were between 0.58 and 0.63. The production parameters that had strong relationships with the net fish yield were feed supply ( r 2=0.960), stocking rates ( r 2=0.924) and feeding rates ( r 2=0.961). In contrast, the length of the production cycle was not strongly related to the net fish yield ( r 2=0.187). Conclusion Nutrient loading from the supplied feed was greater than that from the harvested fish, juvenile fish and dead fish. Increasing the net fish yield in floating cages was better predicted by the stocking densities and feeding levels than by the other factors.

Nutrient loading and farm characteristics of giant gourami fish aquaculture systems in Lake Maninjau, Indonesia: basic knowledge of production performance.

Background Aquaculture systems for giant gourami, Osphronemus goramy Lacepède (1801), have significantly improved fish production yields and food security in Indonesia. However, these systems also cause serious problems in terms of eutrophication in waterbodies. This study analysed the nutrient loading and farm characteristics of giant gourami in floating cages in Lake Maninjau. Method A total of 20 floating cages were used to record these nutrients in feed supply, female and male juvenile fish, dead fish and harvested fish to estimate nutrient loading. Data on the harvested fish, production cycle, stock number and cage capacity were used to estimate the stocking density, feeding rate, feed efficiency, and net fish yield, and the relationship between feed supply and nutrient loading and farm characteristics was analysed by least squares regression methods. Results A total of 20 floating cages released nutrients into waterbodies at an average rate of 236.27±60.44 kg/cycle for C, 84.52±20.86 kg/cycle for N and 8.70±3.63 kg/cycle for P. On average, fish production for each floating cage (±SD) was 1226±282 kg wet weight/cycle, and the net fish yield was 12.63±2.82 kg/m 3/cycle. Survival rates ranged from 86.33 to 95.27%/cycle. The production cycles varied from 160 to 175 days with feed conversion ratios between 1.60 and 1.75, feed conversion efficiencies were between 0.58 and 0.63. The production parameters that had strong relationships with the net fish yield were feed supply ( r2=0.960), stocking rates ( r2=0.924) and feeding rates ( r2=0.961). In contrast, the length of the production cycle was not strongly related to the net fish yield ( r2=0.187). Conclusion Nutrient loading from the supplied feed was greater than that from the harvested fish, juvenile fish and dead fish. Increasing the net fish yield in floating cages was better predicted by the stocking densities and feeding levels than by the other factors.

Comparison of net fish yields in pond cultured Nile tilapia (Oreochromis niloticus L.) fed on peanut-based meals as alternatives to dietary fishmeal

Although net yield directly relates to actual production at harvest, feeding trials aimed at replacing dietary fishmeal in cultured fish have largely ignored the performance indicator. A 16-week experiment aimed at comparing Net Fish Yields in Nile tilapia fed on peanut-based meals as alternatives to dietary fishmeal took place at Busoga University farmland in Eastern Uganda. Earthen ponds of size 4.0 x 3.0 x1.0 for length, width and depth respectively were used for culturing the experimental fish. Each of the 16 pond units were stocked at a density of 48 Nile tilapia fingerlings of initial live weight of 21.95 grams. Iso-nitrogenous diets containing 30% and 25% Crude Protein (CP) for the first 12 and last four weeks respectively, were used during the trial. Dietary treatments included the fishmeal (FM)-based diet and two peanut-based diets. The latter consisted of peanut meal (PNM)-based diet and mixed plant meal (MPM)-based diet in a ratio of 50:50. The commercial feed (CF) for grow-out Nile tilapia containing 25% CP acted as a control diet. NFYs of 5668 and 5624 kilograms per pond unit for Nile tilapia fed on the MPM and FM-based diets respectively, showed no significant difference (p>0.05). On the contrary, NFY of 4819 kilograms characteristic to the PNM-based diet was the lowest and significantly poorer (p

Evaluation of different types of feed in carp polyculture

An experiment was conducted to assess the effects of different types of feed on the growth and production of common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella), and rohu (Labeo rohita) for 6 months in 9 ponds of 150 m2 each. They were fed on mash feed (T1), sinking pellet (T2), and floating pellet (T3) @ 5% of total body weight daily along with finely chopped Dubo grass (Cynodon dactylon) for grass carp. Combined extrapolated gross and net fish yield was found the highest in T3, intermediate in T2, and lowest in T1. The feed conversion ratio was found the least in T3 followed by T2 and T1. Total production costs involved in fish production were found the highest in T3 followed by T2 and T1. The gross margin was significantly higher in T2 and T3 than in T1 (p

During the winter, the performance of a temperate-zone channel catfish biofloc technology production system

In an outdoor biofloc technology production system, channel catfish (Ictalurus punctuates) have been successfully produced. In the tropics, outdoor biofloc production systems are used all year, while channel catfish research was limited to the growth season and biofloc production tanks. Harvested and put to rest for the winter. If a biofloc production system is to be used outside, Farmers in temperate latitudes, then, throughout the winter, data gaps related to system and fish performance. This issue must be addressed. The purpose of this research was to fill up these data gaps for channel catfish culture. Low (153.3 mg/L) water from a recently finished biofloc production experiment for this research; high total suspended solids (790.0 mg/L) were maintained. Per water source, there are three 15.7-m3 tanks. For a 152-day period, each type was supplied (8 kg/m3) with market-size channel catfish from the same research. From November through April, you will be studying. During the experiment, mean chlorophyll a concentrations were comparable in both treatments. Treatments diverged after 55 days, and chlorophyll a concentration grew linearly. (P 0.001, R2 = 0.721) in the low solids treatment to a mean final concentration of 2251.7 mg/m3. Ammonia Spikes of ammonium chloride (1.25–1.5 mg TAN) were added three times throughout the experiment. Completely biotransformed, presumably via algal absorption and nitrification. Biotransformation rate of ammonia. In the high solids (P 0.001, R2 = 0.920) and low solids (P 0.001, R2 = 0.920), was directly linked to mean water temperature. Treatments with (P = 0.002, R2 = 0.761). In biofloc tanks, catfish survival was excellent (99.75%) throughout the winter. There were no significant differences between the treatments. There was no significant difference in net fish output between the two groups. Treatments. Net fish yields, on the other hand, were 1–4% lower than starting fish biomasses. In the biofloc, there is water. Regardless of the weather, production tanks seemed to maintain their capacity to biotransform ammonia throughout the winter. Regardless of whether phytoplankton or suspended solids predominate, and despite ongoing ammonia nitrogen addition, having a functioning biofloc in the spring eliminates the need for a lengthy start-up period when establishing a new biofloc. Biofloc is completely functioning, as are the TAN and nitrite spikes.

Effect of Bamboo Substrate on Growth and Production of Carp and Small Indigenous Fish

A field trial was conducted to examine effects of substrates on yield of carp and SIS at Sukranagar Village, Chitwan district for 210 days in farmer’s pond. The experiment was designed with four treatments: T1 (carp only), T2 (carp+SIS), T3 (carp+substrate) and T4 (carp+SIS+substrate) with four replicates. Ponds were stocked with fingerlings of six carp species at a rate of 20,000 fish/ha and two Small indigenous fish species at a rate of 50,000 fish/ha in 1:1 ratio. Prior to stocking of fish, split bamboo mats were fixed in substrate ponds covering 2% of pond surface area to enhance periphyton growth. Carp were fed with dough of rice bran and mustard oil cake (1:1) at the rate of 3% BW daily while Grass carp was fed with grass and banana leaves at 50% BW. Growth and yield of Rohu and Common carp, combined net fish yield and gross margin were found higher (p&lt;0.05) in carp ponds with substrate.

Lamellidens and Wolffia canopy improves growth, feed utilization and welfare of Labeo rohita (Hamilton,1822) in integrated multi-trophic freshwater aquaculture system

A 90 days' trial on integrated multi-trophic aquaculture (IMTA) incorporating floating weed Wolffia globosa as inorganic extractive and a bivalve Lamellidens marginalis as organic extractive was conducted to assess the growth, survival, yield, water quality and welfare of Labeo rohita (Rohu) in an outdoor tank culture system. Twelve cement tanks (20 m3) were randomly allocated into four treatments (in triplicate) where L. rohita was used as fed species. The treatments were assigned as control (C) only rohu, T1: Rohu and partitioned Wolffia canopy, T2: Rohu, L. marginalis and T3: Rohu, Wolffia and L. marginalis. The stocking densities for rohu and L marginalis were 30,000 fingerlings ha−1 and 750 kg ha−1 while Wolffia was transplanted to cover 30% of the tank surface area, and fish to mussel biomass ratio maintained was 2:1. The fish were fed with a sinking pelleted feed (30% Crude Protein) at the rate of 4% body weight. It is observed that total biomass, survival, net fish yield (NFY) was significantly highest in T3 as compared to T1, control and T2. The total protein and lipid content of rohu (whole-body) differ significantly between the treatments. Among the welfare parameters, the nitroblue tetrazolium (NBT) activity was significantly higher in T1 and T3 while superoxide dismutase (SOD) was highest in T1. The catalase (CAT) activity lowest in T3 among all the treatment groups. The water quality parameters like NH4-N, NO3-N, PO4-P were significantly lower in T3 among all treatment groups. Higher water transparency was observed with no algal bloom in T3 and T1. The results suggest that co-culture of L. rohita with W. globosa and L. marginalis can improve water quality, welfare parameters, enhancing fish survival and productivity.

Periphyton based grow-out farming of Indian major carps with Labeo calbasu (Hamilton) and Puntius gonionotus (Bleeker) for better water quality and enhanced fish production

Influence of two levels of periphytic substrate (bamboo mats) on water quality and growth performance of five carp species was studied in grow-out polyculture system in earthen ponds for six months. With similar fertilization and supplementary feeding in all ponds, stripped bamboo mats were provided to create 0, 10 and 20% substrate surface area for periphyton growth and designated as control, T-1 and T-2, respectively. The ponds were stocked with catla, rohu, mrigal, kalbasu and silver barb at equal species ratio and at combined density of 5000 fingerlings ha−1. Provision of periphytic substrates ensured prevalence of better water quality in terms of minimizing fluctuation of water parameters and increasing plankton availability in treatments, besides additional availability of periphytic biomass for feeding. Increased substrate area in T-2 caused more periphyton availability and less grazing pressure than T-1, but no marked influence on the plankton density was observed. The overall treatment survival, growth, SGR and net fish yield significantly increased with provision of substrate. Among the species, only rohu and kalbasu recorded significant increase in their growth in treatments than the control. But no significant growth difference of these species between T-1 and T-2 indicated 10% additional substrate area (in T-2 over T-1) was not enough to cause a significant improvement in their weights. However, the higher growth trends in rohu, silver barb and kalbasu with increased substrate area suggested further need to explore the possibility of increasing yield with more substrate, subjected to consideration of economic feasibility.

Alternative dietary protein source for nile Tilapia: Giant African Snail (Achatina fulica, Ferussac, 1821)

The present study was conducted for two months between November 2019 and December 2019 to investigate the growth performance of Nile Tilapia fed with diets containing soyabean 100% (T1), soyabean and Achatina fulica: 50/50% (T2) and A. fulica 100% (T3). The experimental diets were formulated with 45% crude protein content. The stocking density was 30 fingerlings per tank of size 1m*1m*0.8m with three replications for each treatment. The tanks were stocked with the fingerlings of uniform size 9 ± 677 cm and weight 24 ± 0.66g. The experimental fishes were fed twice a day at 5% of their body weight. No significant differences (p˃0.05) in average weight gain, apparent feed conversion ratio (AFCR), daily weight gain, gross fish yield and net fish yield were observed. The study revealed that Giant African Snail (GAS) can be used either as partial or total replacement for soyabean as protein source for the fish. The use of harmful pest A. fulica in fish feed shows bright prospect in reducing the feeding expenses together with its suitable management.

Evaluation of dietary protein requirement for the growth performance of minor carp,Cirrhinus reba(Hamilton, 1822) fingerlings

An experiment was designed to evaluate the requirement of dietary protein for Reba carp, Cirrhinus reba fingerlings using semi-purified diet. Five isocaloric diets were prepared containing 20%, 25%, 30%, 35% and 40% level of protein using casein, gelatin as a major protein source. The experiment was conducted for 105 days in triplicates to evaluate the growth, survival, feed utilization, carcass composition of C. reba. Mean weight gain was highest (p < .05) in T3. Specific growth rate was highest in T3 and lowest in T1. Similarly, significantly (p < .05) highest net fish yield were recorded in T3. No significant difference was recorded in survivability. Feed conversion ratio, protein efficiency ratio, feed conversion efficiency and protein conversion efficiency were significantly (p < .05) higher for T3 compared with other treatments. Highest carcass protein and lipid values were recorded in T3. So, conclusion can be drawn that 30% crude protein is optimum for overall performance. Furthermore, broken-line analysis for specific growth rate, final biomass and net fish yield indicated that dietary protein level of 28.148 to 28.253% is optimum for the best growth performance of fingerling C. reba.

Effects of dietary carbohydrate sources on growth performance, glycogen accumulation, insulin signaling pathway and hepatic glucose metabolism in largemouth bass, Micropterus salmoides

The present study was conducted to investigate the effects of dietary carbohydrate sources, α-cassava-starch, potato starch, pea starch and dextrin, on growth performance, glycogen accumulation, insulin signaling pathway and hepatic glucose metabolism in largemouth bass (initial body weight: 36.34 ± 0.30 g) for 11 weeks. Results showed that pea starch significantly improved the specific growth rate (SGR), daily weight gain (DWG) and net fish yield (NFY) of largemouth bass compared to other starch, which maybe related to the depressed feed conversion ratio (FCR). Meanwhile, fish fed the diet with pea starch obtained the minimum hepatic glycogen content, which is significantly lower than that of α-cassava starch. The above result indicated that the fish was more tolerant to pea starch than other carbohydrate sources in accordance with the result of postprandial glucose content. The expression of insulin receptor (IR), insulin receptor substrate 1 (IRS1) and phosphoinositide 3-kinase regulatory subunit 1 (PI3KR1) was significantly up-regulated in fish fed the diet with pea starch than others, indicating the significantly higher activity of insulin pathway in the pea starch group at least at the transcription level. Meanwhile, pea starch led to a significantly increased expression of glucokinase (GK) and liver-type 6-phosphofructokinase isozyme (PFKL), while dietary starch sources had no significant influence on the expression of phosphoenolpyruvate carboxykinase (PEPCK) and fructose-1,6-bisphosphatase-1 (FBP1). The improved glycolysis and poor inhibited gluconeogenesis may account for the reduced hepatic glycogen content of pea starch. Therefore, pea starch was most suitable starch among the sources used for largemouth bass.

The role of fish-poultry integration on fish growth performance, yields and economic benefits among smallholder farmers in sub-Saharan Africa, Tanzania

Aquaculture practices from sub-Saharan Africa are characterised by low production, owing to improper technology. Production can be increased through integrating fish farming with other existing on-farm activities, particularly livestock husbandry. We assessed the role of fish-poultry integration on all male Nile tilapia, Oreochromis niloticus growth performance, yields and economic benefits among smallholder farmers in sub-Saharan Africa, Tanzania. The study also compared phytoplankton species composition, abundance and biomass between the fish-poultry integration and non-integrated system. After 180 days of the experiment, all male O. niloticus cultured under fish-poultry integration exhibited significantly higher growth rates than those in the non-integrated system (p < 0.05). Gross fish yield (GFY), net fish yield (NFY) and net annual yields (NAY) obtained from fish-poultry integration were significantly higher than those from non-integrated system (p < 0.05). Partial enterprise budget analysis revealed that fish-poultry integration was more profitable than the non-integrated system. Moreover, fish-poultry integrated system produced significantly higher phytoplankton abundance and biomass than those from the non-integrated system. Results demonstrate that rural smallholder farmers can achieve higher growth rate, farm net yields and income by integrating all male O. niloticus with other on-farm activities than practising a stand-alone fish culture system.

Positive impacts of Nile tilapia and predatory sahar on carp polyculture production and profits

Carp polyculture is commonly practiced throughout south Asia, but traditional aquaculture methods often lead to low fish yields from ponds in this region. Two trials were conducted to evaluate the benefits of adding Nile tilapia and sahar to carp polyculture ponds. The first trial was conducted in 9 earthen ponds for 240 days. This on-station trial stocked ponds with three separate treatments: a) carp only (C); b) carp + tilapia (C + T); and c) carp + tilapia + sahar (C + T + S). Combined net fish yield at harvest was significantly higher in the C + T + S trial (2.58 ± 0.10 t·ha−1·crop−1) compared to the C trial (2.01 ± 0.26 t·ha−1·crop−1). Additionally, gross margin (output value minus input costs) was significantly higher in the C + T + S trial (2357 ± 211 USD/ha) compared to the C trial (1300 ± 316 USD/ha), but not compared to the C + T trial (1569 ± 177 USD/ha). Next, an on-farm trial was conducted in 12 farmer-managed earthen ponds for 165 days. This trial focused on two treatment types: a) C and b) C + T + S. Combined net fish yield at harvest was significantly higher in the C + T + S trial (2.78 ± 0.39 t·ha−1·crop−1) compared to the C trial (2.06 ± 0.14 t·ha−1·crop−1). Gross margin was also significantly higher in the C + T + S trial (3219 ± 367 USD/ha) compared to the C trial (1800 ± 250 USD/ha). The use of these alternative species, along with traditional carp, has the ability to increase fish yield and raise profits in polyculture systems.