Compatibility of silver barb Puntius gonionotus (Bleeker) with Indian major carps in a grow-out polyculture

The compatibility and growth performance of silver barb Puntius gonionotus (Barbonymous gonionotus) with the three Indian major carps, i.e., Catla catla, Labeo rohita and Cirrhinus mrigala, were assessed in a 10‐month carp polyculture trial. Treatments T‐1, T‐2, T‐3 and T‐4 were stocked with three of the above four carp species, with an absence of silver barb, mrigal, rohu and catla, respectively, while all four species were stocked in treatment T‐5. The treatments were stocked at 6000 fingerlings ha⁻¹, with an equal species ratio maintained in each treatment. Incorporation of silver barb into the polyculture system neither affected the survival of any carp irrespective of species combination nor yielded significant changes in biomass production among treatments, except for the one without catla, where it was significantly low. The study revealed a higher extent of competition between silver barb and rohu, perceptible from the lower growth of one in the presence of the other. Although a certain level of competition of silver barb with mrigal was evident, competition with catla was not perceptible. Irrespective of species combination with silver barb as a component species, similar total biomass production in treatments revealed the feasibility of its incorporation into the Indian major carp‐based polyculture practice without affecting the total yield.     

Screening of gastrointestinal bacteria of Indian major carps for a candidate probiotic species for aquaculture practices

Probotic selection could be detrimental for the success of aquaculture practices. While, in most of the cases emphasis is given to the production of antibacterial compounds, and in vitro inhibitory activities of a bacterium for choosing a probiotic strain, however, other criteria like non‐antibiotic resistant, non‐haemolytic nature and non‐pathogenic potentiality of probiotic strain are often overlooked. We have screened gastrointestinal bacteria isolated from all the three species of Indian major carps viz., Labeo rohita, Catla catla and Cirrhinus mrigala for a suitable probiotic. Bacteria like Aeromonas (Aeromonas species, A. hydrophila), Micrococcus, Corynebacterium, Plesiomonas, Bacillus (Bacillus species, B. subtilis) and Pseudomonas (Pseudomonas species, P. aeruginosa) exhibited antibacterial activities against different pathogens. Among these, B. subtilis was found to grow at a wider range of temperatures, pH and salt concentrations and was non‐haemolytic, non‐antibiotic resistant, non‐pathogenic and inhibited all the tested primary and secondary pathogens. Dietary supplementation of the bacteria at 10⁸ CFU g^?1 feed also enhanced the growth of Indian major carp, L. rohita. Based upon these characteristics, we aimed to develop a suitable probiotic for aquaculture practices.     

Application of biofloc technology for Indian major carp culture (polyculture) along with water quality management

In this study, the efficacy of biofloc system was assessed for culturing Indian major carps, e.g., rohu (Labeo rohita), catla (Catla catla), and mrigal (Cirrihinus mrigala) at varied stocking densities (STD) from 4.28, 8.57, and 12.85 fish m⁻³ of tank volume. Biofloc system could efficiently remove inorganic nitrogen from culture water and substantially improved the growth parameters of fishes as compared to the control system without the application of biofloc. Among different STDs in biofloc system, water quality and floc formation were noted to be higher with a STD of 4.28 fish m⁻³ and the average concentration of NH₄ – N, NO₂ – N and NO₃ – N of 0.61 mg L⁻¹, 0.35 mg L⁻¹ and 1.8 mg L⁻¹, respectively was recorded lowest as compared to the other STD. As a result, catla and rohu could achieve a specific growth rate of 1.1 % day⁻¹ and 0.98 % day⁻¹, respectively. However, in the other two STDs, the respective concentrations were noted in the range of acceptable water quality, and the growth rates were satisfactory. It can be concluded that the biofloc system is efficient to culture IMC in polyculture mode amd therefore, can be directly applied in scaled-up culture modules.     

Experiments on second spawning of major Indian carps in the same season by hypophysation

The major Indian carps, rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala), were hitherto known to breed only once a year—during the monsoon season—either in their natural habitat or by hypophysation in captivity. It has been found possible to mature and induce these carps to spawn twice in the same season, within an interval of about 2 months, and thus augment the spawn production. The technique in brief is as follows. (i) The fish are bred by hypophysation early during the monsoon, in June. (ii) After the first spawning, prophylactic measures are adopted. (iii) The fish are fed supplementary feed consisting of groundnut oil cake and rice bran at a ratio of 1 : 1 and 2–5% body weight of the fish. The spent fish, under favourable weather conditions, were found to mature for a second time and were ready for a second spawning, using hypophysation, in about 2 months. This finding is a breakthrough in the field of fish culture at it helps to obtain more spawn from the same specimens in one season. These results demonstrate the possibility of extending this practice to other cultivated species and thereby augmenting the supply of quality fish seed.     

Effects of increasing the stocking density of large carps by 20% on 'cash' carp–small fish polyculture of Bangladesh

This experiment was carried out in the framework of a project to develop a viable fish polyculture technology under Bangladeshi conditions that allows simultaneous fish production of small indigenous species for the farmers' family consumption and of large carp species as a cash crop. The objectives of this experiment were to assess the effects on fish performance and on the environment of adding 20% large fish to the basic ‘cash crop’ carp–small fish polyculture consisting of 10 000 fish ha^?1 of the large carp rohu Labeo rohita (Hamilton), catla Catla catla (Hamilton) and common carp Cyprinus carpio (L.) at a species ratio 1:1:1, and 15 000 fish ha^?1 of each small indigenous fish punti Puntius sophore (Hamilton) and mola Amblypharyngodon mola (Hamilton) (control). The treatment ponds were stocked with additional 2000 large fish ha^?1, either all rohu, or all catla, or all common carp, or half rohu and half common carp, or half catla and half common carp. The results obtained and the analysis of interactions through the food web that affect food resource availability of the different fish species and account for the trends and differences observed among treatments confirm the positive effect of common carp on rohu reported in previous experiments and show that a 20% increase in large carps stocking neither affect the survival of the large carps nor reduce harvesting biomass of the small fish for the farmer's family consumption. Increased stocking densities of each large carp species did not significantly reduce its own harvesting weight and mean growth rate, while significantly increased rohu and catla (but not common carp) harvesting biomass and yield. The complex relations between species led to inter‐ and intraspecific competition, which in some treatments increased growth or yield of one species and in other treatments of other species, so that the gains on one species and the losses on the other led to no significant total harvested biomass differences between treatments. Yet, the results herein reported may help farmers to select their species stocking ratios. Thus, if the main target of the farmer is rohu, then a stocking density increase of 10% common carp and 10% rohu would improve rohu growth rate (due to common carp) and result in 50% higher rohu harvesting biomass and yield. If the main target of the farmer is catla, then a 20% increase in catla stocking density would lead to 20% higher catla harvesting biomass.     

Effects of feed restriction on compensatory growth performance of Indian major carps in a carp–prawn polyculture system: a response to growth depression

Effects of feed restriction on compensatory growth (CG) performance of Indian major carps, sediment loading and water productivity in a carp–prawn grow‐out production system were examined. The overall growth and crop performance were in the similar line in both T₁ (regular feeding, 2 times a day) and T₂ (4‐week feeding followed by 2‐week no feed). However, between T₁ and T₃ (8‐week feeding followed by 2‐week no feed), there was a significant (P < 0.05) variation in the overall growth and crop performance. This was probably due to the longer refeeding periods after cyclic food deprivation that successfully triggered compensatory growth response in T₃ (CG Index: 98–104%). Treatment‐wise sediment load ranged between 59.2 and 69.6 m³ t^?1 biomass. Higher the apparent feed conversion ratios, higher was the sedimentation rate. Higher the feed input, higher were the water exchange requirement, total water use and consumptive water use index. Cyclic food deprivation and refeeding also helped in maintaining water quality due to the restricted feed input (10.5% in T₂ and 2.0% in T₃), thus minimizes the input cost and improves production efficiency. Keeping the growth and yield performance, water productivity and economic efficiency in view, T₃ is considered the best feed management protocol followed by T₂ and T₁.     

A comparative study on innate immunity parameters in the epidermal mucus of Indian major carps

The innate immune system, particularly the external body surface, plays a frontier role in protecting fish from relevant infections. The present study is aimed at understanding and comparing the mucosal immunity of Indian major carp, that is, Labeo rohita, Catla catla and Cirrhinus mrigala, by evaluating different immune parameters such as protein content, lysozyme, myeloperoxidase, proteases and alkaline phosphatase activity in the skin mucus. The protein content of mucus sample of these species was compared, and the highest protein content was found in C. catla among the three Indian major carp species. The levels of proteases (40 ± 0.211 units/ml) and myeloperoxidase OD450 nm (1.525 ± 0.108) were found to be highest in the skin mucus of C. catla. However, lysozyme levels were highest in the skin mucus of L. rohita (10.95 ± 0.330 μg/ml), and C. mrigala had the highest alkaline phosphatase activity (30.74111 ± 0.680 U/l). Besides the enzyme activities, the epidermal mucus samples of three Indian major carp species were also tested and compared for the antibacterial activity against seven bacterial strains. Skin mucus of C. catla showed highest antibacterial activity among the three Indian major carps against all the seven bacterial strain, except that Micrococcus lysodeikticus and Vibrio cholerae, however, showed highest activity against mucus of C. mrigala. Also, the epidermal mucus from all the three species successfully agglutinated three freshwater pathogens, viz. Aeromonas hydrophila, Pseudomonas fluorescens and Edwardsiella tarda, with agglutination titres being the highest for Labeo rohita for all the pathogens. The epidermal mucus samples from the Indian major carp species showed haemagglutination activity and successfully lysed human, chicken and goat RBCs showing highest activity in C. catla. These results provide information for a better understanding of the role of epidermal mucus and its components in the innate immune system of Indian major carps.     

DNA fingerprinting in Indian major carps and tilapia by Bkm 2(8) and M13 probes

DNA fingerprints were obtained in three species of commercially important freshwater fishes, Labeo rohita (Hamilton). Catla catla (Hamilton) and Oreachromis mossambicus (Peters), using Bkm 2(8) and M13 multilocus probes. Bkm 2(8) gave a higher number of bands when compared with M13. However, the number of bands obtained by each probe in O. mossambicus was similar. The higher band-sharing coefficient observed in this species may be attributed to inbreeding as it arose from a small founder population. In L rohita and C. catla, the Bkm 2(8) detected similar DNA fingerprints when two enzymes Hinfi and Taqi were used. The M13 probe also gave similar fingerprints with three restriction enzymes (Hinfi, Taqi, Alui). Comparison of the DNA fingerprints obtained by Bkm 2(8) and Ml 3 showed that these two probes detected different alleles. The overall similarity of the DNA fingerprint patterns in L. rohita and C. catla may be due to their genetic closeness as indicated by their same chromosome number, C-value and their ability to produce fertile hybrids. A similar argument also holds true for the Oreochromis species where interspecies hybridization results in fertile offspring.     

淡水池塘黄鳍鲷与南美白对虾混养技术

黄鳍鲷又名黄脚立、黄加拉、赤翅,属鲈形目、鲈亚目、鲷科、鳍鲷属,肉质佳美,营养丰富,经济价值较高,黄鳍鲷适应力强,在河口区半咸水域均有分布,为杂食性鱼类,生长快。近年来,我县淡水池塘养殖南美白对虾通过不断探索鱼虾混养新技术来摆脱困境,2009年4月至9月,黄鳍鲷与南美白对虾混养试验取得成功,效益显著,现将技术情况介绍如下。     

Grow‐out performance of Kuria labeo,Labeo gonius (Hamilton), with major carps in carp polyculture system

A year‐long grow‐out carp polyculture trial was conducted in nine earthen ponds to study the growth performance of Kuria labeo (Labeo gonius) with the different major carps such as catla (Catla catla), silver carp (Hypophthalmichthys molitrix), rohu (Labeo rohita) and mrigal (Cirrhinus mrigala). Suitable water quality parameters were maintained in ponds through intermittent liming, manuring and fertilization. Three different species combinations of carps were evaluated using silver carp and catla as the common species and varying other carp components as rohu–Kuria labeo, mrigal–Kuria labeo and rohu–mrigal in the three treatments. The ponds were stocked at a combined density of 7500 fingerlings ha^?1. Silver carp and catla showed similar growth performances in all the three combinations, suggesting that other carps in the combination do not have any differential influence on their growth. Kuria labeo was compatible with rohu, while competition was observed with mrigal. Although growth performance of Kuria labeo was inferior to that of mrigal, better compatibility of Kuria labeo with rohu helped this combination to yield a biomass equivalent to the mrigal–rohu combination, suggesting feasibility to use Kuria labeo as an alternative species to mrigal in the major carp polyculture system without compromising the total biomass yield.     

Influence of water exchange rates on fingerling production in Indian major carps in large outdoor concrete tanks

Influence of varied water exchange (total of 0%, 40%, 60%, 80% and 100% in four phases during three months) on fingerling production of Indian major carps-catla, rohu and mrigal under polyculture was evaluated in large outdoor concrete tanks (50 m²). Rearing density of 30 fry m⁻³ was used. Survival in the control tanks reduced during the 2nd month unlike the treatments, attributed to lack of water exchange in the tanks. While no marked variation in water quality was observed among the control and treatments, graded water exchange led to proportionate improvement in the fingerling performance in terms of survival and growth in the treatments. Harvested total lengths of fingerlings were similar in all, irrespective of varied exchange levels. Although no significant variation in net weight gain (NWG) and specific growth rate (SGR) were observed among the treatments during 1st and 2nd months of rearing in any of the species, these attributes increased significantly during 3rd month with higher water exchange in treatments. The harvested body weight (HBW) also increased significantly with increased exchange level. However, survival, HBW, NWG and SGR remained similar in all species between the 80% and 100% water exchange levels. Treatment with 80% water exchange had higher water productivity in terms of number and biomass production of fingerlings per unit (m⁻³) of TWU and CWU for which, the study recommended 80% to be the ideal total water exchange required for fingerling production of IMC in concrete tanks.     

对虾池混养缢蛏高产技术

缢蛏肉味鲜美,营养丰富,是我国沿海群众喜爱的海味佳品.养殖缢蛏具有生产周期短,易管理,成本低,效益高,投资少,见效快等特点.在对虾塘里混养缢蛏,可充分利用水体,不但可以增加贝类的产量;还可避免因残饵腐败引起的水质恶化,减少虾病发生;贝类的排泄物又能促进浮游生物和底栖硅藻的繁殖,为对虾提供天然饵料,有利于对虾生长,形成良性循环,达到虾贝双丰收的目的.     

虾池养殖大西洋牙鲆技术探讨

大西洋牙鲆是分布于北美洲大西洋沿岸的一种底层鱼类,是一种极具发展潜力的养殖新品种。它对环境的适应能力比较强,能适应不同的养殖条件。利用对虾养殖池养殖大西洋牙鲆有非常广阔的前景。将对虾养殖池经过清淤、消毒进水,于5月下旬前后投放10cm左右的大西洋牙鲆鱼苗,经过投饵、水质管理等措施;到11月下旬前后出池,出最大个体达756g,平均437g。     

无公害蟹池套养鳜鱼生产技术要点

1 池塘条件 水源要求水量充足,水质良好,符合NY5051标准,进排水系畅通.面积以6 000～20 000m2为宜.水深在1.2～2.0m之间.形状以东西走向为佳.底质以粘土为好,粘壤土次之,淤泥在10～15cm之间.     

海水池塘虾蟹贝生态养殖中后期管理技术

山东省日照市东港区涛雒镇朝阳村养殖场创新养殖模式,实行虾、蟹、贝生态健康养殖,实现了良好的经济效益与生态效益,带动了周边海水池塘养殖发展,2008年被确定为农业部水产健康养殖示范场。     

Identification of gut‐associated amylase,cellulase and protease‐producing bacteria in three species of Indian major carps

Isolation and enumeration of amylase, cellulase and protease‐producing autochthonous bacteria in the proximal intestine (PI) and distal intestine (DI) of three species of Indian major carps, catla (Catla catla), mrigal (Cirrhinus mrigala) and rohu (Labeo rohita), were investigated using the conventional culture‐based technique. Population levels of amylolytic strains were the highest in the PI of catla and the lowest in the DI of rohu. The highest viable count of cellulase and protease‐producing bacteria was recorded in the DI and PI of mrigal respectively. Among the bacteria isolated, 10 strains (five from PI and five from DI) were selected as potent enzyme producers according to a quantitative enzyme assay. The chosen strains were further identified by 16S rRNA gene sequence analysis. The five strains isolated from catla showed high similarity to Citrobacter sp. clone W2, Enterobacter sp. JA24, Bacillus coagulans strain TR, uncultured bacterial clone Hel3bc04 and Bacillus cereus strain UST2006‐BC004. The four strains isolated from mrigal were most closely related to Bacillus sp. KCd2, uncultured bacterial clone Hel3bd09, B. cereus strain BU040901‐020 and Citrobacter freundii strain YRL11, while the strain isolated from rohu probably belonged to Bacillus sp. GV.     

Effects of all‐male,mixed‐sex and all‐female freshwater prawn in polyculture with major carps and molas in the fallow rice fields

This study was conducted to evaluate the effects of all‐male, mixed‐sex and all‐female freshwater prawn (Macrobrachium rosenbergii) in a polyculture with major carps (Catla catla and Labeo rohita) and self‐recruiting small fish molas (Amblypharyngodon mola) in the fallow rice fields of Bangladesh. There were three treatments with three replicates. All ponds were stocked with carps and molas plus either all‐male prawns (treatment MP), mixed‐sex prawns (MFP) or all‐female prawns (FP). Prawn, mola, catla and rohu were stocked 20 000, 20 000, 1750 and 750 ha^?1, respectively, in all treatments. The prawns were fed twice daily, starting at 8% body weight and gradually reduced to 3% body weight. The fish were fed in the morning with mustard oil cake and rice bran (1:2 ratios) at 3% body weight. Significantly higher production of prawns (697 kg ha^?1) was obtained in treatment MP, which yielded 34.7% and 56.2% more production than MFP and FP respectively. Significantly higher total production of 1620 kg ha^?1 and a higher benefit–cost ratio of 2.10:1 were also obtained in treatment MP. It can be concluded that an all‐male prawn culture is economically more viable than all‐female and mixed‐sex prawn cultures, along with other fish like major carps and the nutrient‐dense molas in the polyculture.     

Production performance of Labeo calbasu (Hamilton) in polyculture with three Indian major carps Catla catla (Hamilton), Labeo rohita (Hamilton) and Cirrhinus mrigala (Hamilton) with provision of fertilizers,feed and periphytic substrate as varied inputs

Inclusion of kalbasu, Labeo calbasu as a candidate species in the Indian major carps based polyculture system was evaluated through a six-month grow-out trial in earthen ponds of 0.08 ha each. Species performance was assessed through provision of varied inputs viz., fertilizers (T-1), fertilizers + supplementary feed (T-2) and fertilizers + supplementary feed + periphytic substrate (T-3) as the three treatments, which were evaluated in replicates. Catla (35%), rohu (35%), mrigal (15%) and kalbasu (15%) were stocked at combined density of 7500 fingerlings/ha. While ponds were fertilized with cowdung, urea and single super phosphate, mixture of groundnut oilcake and rice bran at 1:1 (w/w) was provided as supplementary feed. The periphytic substrate, comprised stripe bamboo mat, was provided at 10% of the pond surface area. Provision of each additional input caused significantly higher increase in overall mean survival, growth, SGR and net biomass yield of carps. Among the carp species, while only rohu and kalbasu showed significantly higher weight gain (234.4 g and 170.3 g, respectively) in T-3, no such increase was noticed either in catla or mrigal. The net production in T-3 (1516.1 ± 24.3 kg ha^− 1 6 months^− 1) was 13.0 and 73.2% higher than those of T-2 (1341.7 ± 15.5 kg ha^− 1 6 months^− 1) and T-1 (875.2 ± 15.6 kg ha^− 1 6 months^− 1), respectively. The study revealed the relative advantage of using periphytic substrates in carp polyculture systems with kalbasu as a component species.