Performance of common carp,Cyprinus carpio L. and Nile tilapia,Oreochromis niloticus (L.) in integrated rice–fish culture in Bangladesh

Irrigated rice fields have enormous potential for expanding the aquaculture production in rice producing countries. Two field experiments were carried out at the Bangladesh Agricultural University, Mymensingh, to optimize the productivity of integrated rice–fish systems using Nile tilapia, Oreochromis niloticus (L.), and common carp, Cyprinus carpio L. Both experiments were laid out in a randomized complete block design with three replicates per treatment and regular rice monoculture as control. In the first trial, carp and tilapia were tested in single culture and in mixed culture with supplementary feeding at 2× maintenance level. The highest fish yield was obtained in the carp/tilapia mixed culture (586 ± 125 kg ha^− 1), followed by tilapia alone (540 ± 65 kg ha^− 1), and carp alone (257 ± 95 kg ha^− 1). Carp had significantly lower yield than the other two fish groups (p < 0.05) due to high mortality and inefficient feed utilization. As the carp/tilapia combination performed the best in the first experiment, it was tested with different inputs in the second trial, i.e. regular urea fertilization and two different feeding levels. The feeding levels were: continuous feeding at 2× maintenance level (feed level I) and a declining feeding schedule from 4× to 2× maintenance level (feed level II). The highest fish yield was obtained in feed level II (935 ± 29 kg ha^− 1), followed by feed level I (776 ± 22 kg ha^− 1), and the non-fed group (515 ± 85 kg ha^− 1). Yield differences between the treatments were significant at p < 0.05. Rice yields showed controversial effects between the rice–fish treatments and were dependent on the inputs provided. The highest rice production (4.2 t ha^− 1) was obtained from rice–fish plots with regular urea fertilization. Various significant effects of fish on water quality parameters were observed. Fish decreased the dissolved oxygen (DO) and pH value compared to rice only, especially when supplementary feed was provided. Moreover, fish stimulated the growth of phytoplankton and increased chlorophyll-a concentration. In conclusion, carp/tilapia mixed culture with supplementary feeding was found to be optimal for maximizing the output from rice–fish culture.     

Artificial spawning of carp, Cyprinus carpio (L.)

The effect of reproduction was investigated on females of Hungarian strain W, French strain F, and their cross‐breed 1X whose ovulation was stimulated with carp pituitary (0.3 mg kg^?1and, after 12 h, 2.7 mg kg^?1) or Ovopel (one‐fifth of a pellet per kg and, after 12 h, one pellet per kg). It was found that in the case of Ovopel treatment, the percentage of spawning females of strain F and the cross‐breed 1X was higher than in the hypophysed fish compared. The applied ovulation stimulators did not significantly affect the weight of obtained eggs, whereas the significant (P ≤ 0.01) effect was recorded with respect to the quality of eggs after 12‐, 24‐, 36‐ and 48‐h of incubation. After Ovopel stimulation, the quality of eggs was better. The origin of the females had no statistically significant effect on the weight of eggs although the yield of eggs from fish of strain W was much smaller than that from females of strain F and the 1X cross‐breed. The interaction between the ovulation stimulator and the provenance of the females was significant (P ≤ 0.05) for the percentage of live embryos after 48‐h of incubation of eggs. Eggs of the best quality (and highest weight) were obtained from fish of strain F and cross‐breed 1X treated with Ovopel. In females of strain F that spawned within 6 and 10 h after the second Ovopel injection, the effect of the ovulation time on the weight of eggs was non‐significant. It was significant with respect to the percentage of egg fertilization and of live embryos after 36‐h of incubation (P ≤ 0.01 and P ≤ 0.05 respectively). The better quality of eggs (and their higher weight) was recorded when this time was shorter.     

Growth performance and use of natural food by Oreochromis niloticus (L.) in polyculture systems with Barbodes gonionotus (Bleeker) and Cyprinus carpio (L.) in intensively cultivated rice fields

In the freshwater area of Vietnam's Mekong Delta, Oreochromis niloticus (L.), Barbodes gonionotus (Bleeker) and Cyprinus carpio (L.) are often reared together in rice fields. In this study, we report the results of eight such polyculture experiments, examining variables affecting the specific growth rate and the average daily food energy consumption of individual O. niloticus. The standing biomass of O. niloticus and the wild fish biomass had a negative impact on the specific growth rate, whereas added pig manure, extra feed and inorganic fertilizer had a positive effect. The standing biomass of O. niloticus and C. carpio, and the wild fish biomass had a negative impact on the consumption of natural feed. We inferred that O. niloticus mainly lacks food in rice fields. This results in intraspecific competition. As in rice fields, C. carpio has basically the same feeding niche as O. niloticus; we found interspecific competition between the two species. O. niloticus consumed relatively more food in the vegetative phase of the rice crop, probably because of a higher abundance of phytoplankton. To get higher growth of O. niloticus, we recommend that farmers increase nutrient inputs and stock O. niloticus according to the size of the trench adjoining the rice field and not according to the size of trench plus field as is generally done.     

Effect of fluoxymesterone on sex ratio and growth of Nile tilapia, Oreochromis niloticus (L.)

The androgenic and anabolic potential of fluoxymesterone (FM) was evaluated by incorporating the hormone into the feed of Nile tilapia, Oreochromis niloticus(L.) fry. Phenotypic all-male populations were produced when FM was given at 1, 5 and 25mg/kg of feed. Fry fed methyltestosterone (MT) at 60 mg/kg of feed and 0-2 mg of FM per kg of feed had a sex ratio of 97-7% and 87-3% phenotypic males. No positive anabolic effect was evident in response to adding FM or MT to the feed at the end of the 28-day treatment period or after an additional 6 weeks of growth without hormone. Growth was less for fry which received 25 mg/kg of FM compared to those receiving lesser rates of FM, 60 mg/kg MT, and controls.     

Induction of Triploidy and Tetraploidy in Nile Tilapia, Oreochromis niloticus (L.)

Abstract.— Induction of triploidy and tetraploidy in Nile tilapia, Oreochromis niloticus , was investigated by heat shock, cold shock, hydrostatic pressure, and/or chemicals (cytochalasin A, B, and D). Additionally, efficacy of combined protocols was determined. Heat shock 10 min after fertilization induced triploidy when incubation temperature was 24 C but not when incubation temperature was 31 C. Heat shock of 40–41 C at 4–6 min after fertilization was effective in inducing up to 100% triploidy with hatchability similar to controls. Cold shock at 13 C for 45 min five min after fertilization induced 85–100% triploids. Heat shock and multiple heat shocking were the most effective treatments for the induction of tetraploidy. Two heat treatments of 41 C applied at 65 and 80 min after fertilization for 5 min each produced approximately 80% tetraploidy in hatched fry. Immersion of fertilized eggs in cytochalasin A, B, or D at concentrations up to 10 μg/L applied at various times and durations was ineffective in inducing triploidy or tetraploidy.     

Improving spawning synchrony in the Nile tilapia, Oreochromis niloticus (L.)

Abstract. The development stage and number of seed (eggs and fry) removed from individual incubating Oreochromis niloticus (L.) broodfish at 10-day interharvest intervals (IHI) was compared with the harvest of free-swimming fry from undisturbed fish held in a tank within the same system. Spawning synchrony and productivity were compared for (1) total exchange of females for ‘conditioned’ females after each harvest, (2) exchange of only spawned females, and (3) return of females back into the spawning tank. Improved synchrony and seed production were positively related to removal of eggs and fry from incubating females and could have important implications for broodstock management in commercial hatcheries. Allowing fish to remain undisturbed in clear water tanks may lead to inhibition of spawning activity related to the formation of hierarchies. Individual weight loss by females during incubation was correlated with stage of seed harvested and thus with timing of spawning during the interharvest interval.     

The diet of hybrid red tilapia Oreochromis niloticus (L.) Oreochromis mossambicus (Peters) reared in the freshwater ponds of north-eastern Brazil

To assess potential competition for food with indigenous species prior to their release into reservoirs in north-eastern Brazil, the diet of hybrid red tilapia, Oreochromis niloticus O. mossambicus, maintained without supplementary feed in monocultures in freshwater ponds, was studied. The stomach contents of 160 fish (140–220 mm total length), collected monthly from February to September 1993, were analysed. Fish of all size categories were found to be phytoplanktivores. A total of 40 microalgal species were observed in the stomach contents (17 species of Chlorophyceae, 11 species of Bacillariophyceae, eight species of Cyanophyceae, three species of Chrysophyceae and one of Euglenophyceae), together with a few rotifers and some organic material. In terms of cell numbers, the overall composition of the diet was 70% Chlorophyceae, 21% Bacillariophyceae, 3% Chrysophyceae, 2% Cyanophyceae, 1% Euglenophyceae and 3% organic matter. Neither diet composition nor stomach fullness varied with fish size. However, fish had relatively fuller stomachs, with higher proportions of Chlorophyceae, Bacillariophyceae and Cyanophyceae, during the rainy season. Hybrid red tilapia appear unlikely to compete for food with a native species and so may have a role in aquaculture or for deliberate release into reservoirs in north-eastern Brazil.     

鲤鱼和斑马鱼同义密码子使用偏性分析

本研究利用鲤鱼454测序所获得的基因的表达序列和GeneBank中斑马鱼全部基因的编码序列,采用多重变量分析软件CodonW对鲤鱼和斑马鱼影响密码子用法的因素进行了分析.结果表明,两个在59种同义密码子中有27种为最优密码子.伺时还指出,最优密码子的使用频率(Fop)与基因的G+C含量(GC),尤其是第三位密码子的G+C百分含量(GC3S)、密码子适应指数(CAI)和密码子偏爱指数(CBI)之间均呈现极显著的正相关(鲤鱼和斑马鱼的相关系数分别为r=0.4108和0.4087、0.5354和0.5628、0.7547和0.7771、0.9803和0.9741),而与有效等位基因数ENc存在显著负相关(相关系数r=-0.2832和-0.2390).表明基因GC含量直接影响密码子使用的偏性,同时基因的表达水平越高,对密码子的使用偏向性越强.     

镉对鲤血清促性腺激素和生长激素的影响

采用ＣｄＣｌ２浸没法处理鲤，研究镉对鲤血清促性腺激素（ＧｔＨ）和生长激素（ＧＨ）水平的影响，结果表明，较镐浓度镉（ＣｄＣｌ２９ｍｇ／Ｌ）处理引起血清ＧｔＨ水平降低，ＧＨ水平升高，提高水中钙浓度，能使由镉引起的ＧｔＨ水平的降低恢得取正常水平，并对镉引起的ＧＨ水平升高起延迟作用，镉处理使鲤对ＬＨＲＨ－Ａ刺激ＧｔＨ分泌的反应性下降，提高水中钙浓度也不能恢复正常，实验结果提示，镉引起的ＧｔＨ和ＧＨ的变化可     

鲤与生长性状相关的EST-SSRs标记筛选

以大头鲤(Cyprinus pellegrini Tchang)(母本)与荷包红鲤(Cyprinus carpio wuyuanensis)抗寒品系(父本)杂交产生的F1作为亲本,以其自交F2作为分离群体,结合"拟测交"策略,用EST-SSRs标记对其中92个个体进行基因型检测.利用Windows Map Manager 2.0的标记回归法对符合拟测交分离的70个EST-SSRs标记进行单标记回归分析,检测出8个与鲤体长、体高、体厚性状相关的标记.对同一标记不同基因型个体间生长性状进行显著性比较,通过t检验,找到与生长性状相关的基因型.将上述8个EST序列与GenBank数据库进行BLAST比对,有3条EST序列与蛋白库中已知功能的序列高度同源.其中HLJE225与编码斑马鱼(J9enio rerio)冷诱导基因RNA结合蛋白的基因同源性水平高达97%,HLJE222与编码斑马鱼DAZ相关蛋白1基因同源性水平也高达97%,HLJE599与编码斑点叉尾鲴(Ictalurus punctatus)核糖体蛋白L6基因的同源水平为87%.本研究鉴定的与鲤生长性状相关的功能基因及有利用价值的基因型,为鲤重要生长性状的QTL(数量性状基闪座)定位和分子标记辅助育种提供了一定的依据.[中国水产科学,2009,16(1):15-22]     

Small-scale fry production systems for Nile tilapia, Oreochromis niloticus (L.)

Abstract Experiments were conducted to evaluate and compare the production, quality and survival of eggs and the subsequent growth and survival of fry in two small-scale production systems: natural incubation and egg collection followed by artificial incubation. Artificial incubation produced a significantly greater number and biomass of fry per unit weight of female broodstock (P < 0·05). This was due to the significantly decreased spawning interval in females from which eggs were collected (mean = 23· days) compared to naturally incubating females (mean = 36·8 days). It is also hypothesized that survival during artificial incubation (85%) is greater than in natural incubation. Cost-benefit analysis demonstrated a threefold increase in total net returns for artificial incubation.     

Immunomodulatory effect of cimetidine in common carp (Cyprinus carpio L.)

The main indication of cimetidine is being H₂-receptor antagonist, but studies suggest that cimetidine may also act as a non-specific stimulant of cell-mediated immunity and immunomodulator. In order to determine the immunomodulatory effect of dietary intake of cimetidine in the common carp (100 ± 10 g), subjects were fed diets containing 0 (control), 50, 100 and 200 mg cimetidine kg^?1 of dry diet for a period of 6 weeks. TLC and NBT assays were significantly (P < 0.05) stimulated in cimetidine-supplemented groups displaying the highest value in 200 mg kg^?1 group. A decrease (P < 0.05) in cortisol and ACH50 value was recorded in fish treated with cimetidine. Serum protein, albumin and serum globulin levels were not significantly changed. The findings of the present investigation suggest that the incorporation of cimetidine in the diet of common carp enhances the non-specific immunity.     

Polyculture of silver barb, Puntius gonionotus (Bleeker), Nile tilapia, Oreochromis niloticus (L.), and common carp, Cyprinus carpio L., in Vietnamese ricefields: fish production parameters

The fish production parameters of five polyculture combinations, consisting of small and large silver barb, Puntius gonionotus (Bleeker), small and large Nile tilapia, Oreochromis niloticus (L.), and small common carp, Cyprinus carpio L., fingerlings in three replicates, were investigated in a rice-fish culture experiment (duration 149 days) conducted in the Mekong Delta, Vietnam. The survival rate was not significantly (P > 0.05) affected by the polyculture combination, but when grouped according to species, the mean survival of silver barb and tilapia was 64.3% and 63.7%, respectively, significantly higher than the mean common carp survival rate (33.4%). The growth of silver barb and tilapia was proportionally related to the stocking density, probably because of intraspecific competition and a synergistic interaction between silver barb and tilapia. The growth of common carp was not significantly different among the polyculture combinations. The highest net production (474.1 kg ha^?1) was obtained in the polyculture combination consisting of 80% small-sized silver barb fingerlings, but the fish was not marketable at that time. In concurrent rice-fish culture, it is recommended to raise large silver barb fingerlings. Small tilapia can be polycul-tured with silver barb, provided a stocking density lower than 1400 ha^?1. Common carp is considered less suitable because of a limited tolerance for the water quality conditions in the ricefield and the large size required by the market.     

Individual heterozygosity levels and relative growth performance in Oreochromis niloticus (L.) cultured under Fijian conditions

Tilapia (Oreochromis spp.) (Pisces: Cichlidae) are important freshwater fishes that are widely cultured worldwide and have been introduced to the Fiji islands as an aquaculture resource. An O. niloticus (L.) ‘Chitralada’ stock cultured under Fijian conditions was studied to assess the potential of using individual multilocus heterozygosity as an indicator of relative growth performance. Allozyme analysis was undertaken in each of three generations (n = 50/generation) of ‘Chitralada’ grow-out. Subsequent correlation and regression analysis of 25 allozyme loci with individual body weights demonstrated no significant association between individual heterozygosity and growth rate in any of the generations. Correlation analysis between heterozygosity based on nine microsatellite loci screened in a subset of ‘Chitralada’ individuals (n = 43, generation 2) and morphological measurements, demonstrated a significant relationship between heterozygosity at locus UNH146. Homozygous individuals at this locus were characterized by larger lengths and weights than heterozygotes. No significant correlations with either length or weight were observed at any of the other eight microsatellite loci. Selecting broodstock therefore based solely on individual allozyme or microsatellite heterozygosity levels is unlikely to increase relative growth performance in the Fijian cultured O. niloticus‘Chitralada’ stock.     

Use of shrimp protein hydrolysate in Nile tilapia (Oreochromis niloticus, L.) feeds

A 45-day feeding trial was carried out to evaluate the use of shrimp protein hydrolysate (SPH) in diets for Oreochromis niloticus, L. SPH was included in isonitrogenous diets replacing fish meal protein by 0, 5, 10, and 20% and offered to Nile tilapia juveniles (1.7 ± 0.4 g) stocked in 40-L glass aquaria. The inclusion of SPH produced no significant differences (P ≥ 0.05) in final weight, survival, weight gain, average daily gain, specific growth rate, feed conversion ratio, protein efficiency ratio, or apparent net protein utilization. The inclusion of SPH Nile tilapia diets significantly affected (P < 0.05) the final fish body composition. Protein and ash contents decreased and fat content increased slightly with the increase in SPH. This study has demonstrated that SPH is a promising protein feedstuff and could account for as much as 6% of Nile tilapia diets with no adverse effects on growth and nutrient utilization.     

Effect of stocking density on growth and survival of Oreochromis niloticus (L.) fry in the hatchery

Abstract. The effect of stocking density on growth and survival of Oreochromis niloticus (L.) fry was evaluated. O. niloticus fry (average weight, 10·56 ± 0·28mg and average length. 9·09 ± 0·05nim) were stocked in 2–1 tanks at 2, 5, 10, 15 and 20 fry/1 and reared for 33 days post fertilization, at 30°C (±1°C). Mean lengths, mean weights, and specific growth rates were found to be significantly lower ( P < 0·05) at the higher stocking densities. The coefficient of variation for the five stocking densities was significantly ( P < 0·05) different. Condition factors, however, were not significantly ( P < 0·05) different and survival was high at all density treatments. These data suggest that the culture of O. niloticus is feasible at the density groups tested but 5–10fry/I is recommended for fry culture in the hatchery, if a more uniform size is desired.     

Simulation of the effects of oxygen on food consumption and growth of Nile tilapia, Oreochromis niloticus (L.)

Fish need oxygen for aerobic generation of energy for body maintenance, locomotion, feeding and biosynthesis. The rate of oxygen uptake of most fish is limited by diffusion through the gills, and gill surface area grows at a slower rate than body mass. We hypothesize, therefore: (1) that the maximum rate of feed intake is related to the capacity to take in oxygen for processing of this feed; and (2) that the maximum rate of feed intake relative to body size decreases with increasing body size to a point where growth is zero. An oxygen limitation module based on this theory was incorporated into an existing dynamic simulation model for the Nile tilapia, Oreochromis niloticus (L.). The module calculates the maximum potential oxygen supply to the fish on the basis of Fick's law of diffusion and the allometric relationship between body weight and gill surface area. Total oxygen demand of the fish is computed as the sum of routine metabolism, feeding metabolism and energy needed for biosynthesis. In the module, the feeding rate is limited to a level where total oxygen demand does not exceed the potential supply. The model is used to simulate feeding and growth of O. niloticus. Simulation results provide strong support for the oxygen limitation theory. Hence, the model can be used for the analysis of fish growth as affected by feed amount, feed composition, as well as environmental conditions (temperature, dissolved oxygen concentration). It also explains differences in final size between fish species, and within species under different conditions.     

Genetic characterization of wild Dutch common carp (Cyprinus carpio L.)

Six male carp, caught in the water system surrounding the Anna Paulowna (AP) Polder in The Netherlands, were characterized using allozyme and microsatellite markers. At the sMDH‐A1,2* loci an allele was found, which has previously only been found in wild River Rhine and wild Vietnamese common carp. Microsatellite allele frequencies showed that these AP carp were significantly different from a group of carp originating from several different domesticated strains. Based on both allozyme and microsatellite data, the AP carp probably originated from a wild or feral self‐sustaining population.     

Economic profitability of Nile tilapia (Oreochromis niloticus L.) production in Kenya

Economic profitability of Nile tilapia production in Kenya was analysed using a model that simulated individual fish growth and took fish population dynamics in the pond into account. The results suggest that the currently practiced mixed‐sex tilapia culture is economically unsustainable. It is suggested that research and extension efforts be geared towards developing monosex Nile tilapia production systems. Nile tilapia culture with African catfish predation should be viewed as an intermediate step towards all‐male Nile tilapia culture. This will allow accumulation of both physical and human capital to support all‐male tilapia culture. Under all‐male culture, economic returns are high enough to justify investment in Nile tilapia culture using borrowed capital. However, the success of monosex culture will depend on the availability and affordability of quality fingerlings and low‐cost fish feeds. The results have a wide application in Sub‐Saharan Africa where mixed‐sex Nile tilapia culture is common.     

Pharmacokinetics of chloramphenicol in carp (Cyprinus carpio L.) after drug administration

Chloramphenicol (CAP) is a banned substance in fish farming; yet, residues are sometimes detected in farmed fish products. Therefore, it is important that tissue distribution and elimination rates of CAP are measured to allow monitoring of fish farms. The tissue distribution and residue of CAP in carp (Cyprinus carpio L.) after muscle injection was investigated. Chloramphenicol concentrations were determined using high‐performance liquid chromatography. Pharmacokinetics were used for the studies of CAP residue and the results showed that the CAP was easily assimilated in the liver, serum and gill, with the absorption rates of 6383, 3.02 and 1.39 h^?1, respectively, following a single‐dose injection of 80 mg kg bw^?1. The elimination half‐lives (t_1/2) were 22.28, 15.47, 14.87, 9.28 and 5.32 h for the liver, serum, gill, muscle and kidney respectively. The t_1/2 after 5 days of multi‐doses of repeated CAP injection with 40 mg kg bw^?1 was 1.09, 0.887, 0.872, 0.476 and 0.617 days for the five tissues respectively. The results validated that CAP in the liver, serum and gill could be markers for CAP residue analysis.