Intensive culture of grass carp, Ctenopharyngodon idella, in circular tanks

Fingerling grass carp ( Ctenopharyngodon idella ) were cultured in 380 1 circular fiberglass tanks at stocking densities of 0.53, 1.06, 1.59 and 2.11 fish/1. Fish were fed duckweed ( Lemna minima ) to satiation. Fish grew from 2.7 g to a maximum mean weight of 72.7 g in 88 days. Fish stocked at 0.53 fish/1 grow more rapidly than those stocked at higher densities. Mean daily consumption rates were strongly correlated with oxygen levels and when oxygen levels dropped below 4 mg/1 consumption was reduced approximately 40%. High biomass, growth, and survival rates obtained during this study indicate grass carp are well suited for intensive tank culture.     

Growth of grass carp fed natural and prepared diets under intensive culture

Grass carp were arranged in two groups with an average individual weight of 63 g and 3 g respectively. They were maintained in circular tanks and each group size was fed one of four experimental diets consisting of Purina catfish chow pellets, 50 % catfish chow ryegrass pellets, 100% ryegrass pellets and fresh duckweed, Lemna minima. In this study a high biomass, excellent growth and satisfactory survival rates were obtained when the fish were fed duckweed; the other diets were less satisfactory. The 100% ryegrass pellets gave the least weight gains and on this diet the smaller fish showed lower survival rates and more abnormalities. The feeding experiment lasted 68 days.     

Morphological comparisons of diploid and triploid hybrid grass carp, Ctenopharyngodon idella♀×Hypophthalmichthys nobilis♂

Morphological and karyological comparisons of 25–28 hybrid grass carp from each of 3 year-classes (1979–1981) indicated that diploid fish resulted during 1979 (82.1%) and 1980 (76.0%) the others being triploid. All of the fish tested from the 1981 year-class were triploid. Most triploid fish differed from diploid fish by having a faster growth rate, fewer scales in the lateral line and transverse series below the lateral line, a relatively longer gut, and fewer deformities.     

Dietary lipid requirement on non-specific immune responses in juvenile grass carp (Ctenopharyngodon idella)

This study aimed to evaluate the dietary lipid requirement and its effects on liver oxidative status and non-specific immune responses of juvenile grass carp (Ctenopharyngodon idella). Purified diets with five dietary lipid levels (0%, 2.5%, 5%, 7.5% and 10%, fish oil/corn oil = 1:1) were each fed to triplicate groups of grass carp (mean initial weight: 6.57 ± 0.01 g) in a recirculating rearing system maintained at 27.5 ± 0.5 °C for 10 weeks. Percent weight gain was highest (P < 0.05) with 5% lipid and lowest in fish fed the lipid free control diet. Feed efficiency (FE) and protein efficiency ratio (PER) in fish followed the same pattern of percent weight gain. Fish fed with lipid containing diets had better non-specific immune response indexes (e.g. phagocytic activity, plasma peroxidase and lysozyme activity) and low-level of liver oxidation status than fish fed with the control diet. But excess dietary lipid supplement would bring over metabolic burden to liver. After the feeding trial, fish were challenged by Aeromonas hydrophila. Fish fed control diet obtained significantly (P < 0.05) lower survival rate. The survival rate was highest with 7.5% lipid. The results of this study indicated that proper dietary lipid supplementation enhanced the immune response of grass carp and improved the survival rate in the bacterial challenge, but excess dietary lipid may elevate liver oxidation rates of grass carp. Analysis by second-order regression of percent weight gain indicated that the optimal dietary lipid level in juvenile grass carp (6.6–35.5 g) is about 6.5%.     

Comparison of early developmental stages and adults of grass carp, Ctenopharyngodon idella, and hybrid carp (female grass carp × male bighead Aristichthys nobilis)

Hybrid carp and grass carp from the zygote to the prolarval stage and adults were compared to establish distinguishing characteristics. Zygote diameter, yolk sac and embryo length were not different between the fishes. Body pigmentation patterns showed distinct separation among the prolarvae of the hybrids and grass carp. Total and preanal myomeres were higher in grass carp larvae than in the hybrids. The grass carp and hybrid larvae also differed in 38% of the proportional morphometric characters.
Average meristic counts of adults were significantly higher in hybrids compared with grass carp. Adults of the two fishes showed significant differences in 63% of the proportional morphometric measurements. Gill raker counts showed no overlap and lateral line scales were smaller and more numerous in the hybrid adults.     

The relationship between feeding preferences and consumption rates in grass carp and grass carp × bighead carp hybrids

The relationship between food preference hierarchy and consumption rate was examined for the grass carp, Ctenopharygodon idella , and its Fl hybrid (grass carp × bighead carp). Preferences of both types of fish were similar, although hybrids consumed vegetation at a much lower rate. For both, relative preference in feeding trials with mixed plant species was significantly correlated with consumption rate in monospecific feeding experiments. No correlations were found between preference and caloric content, protein content or relative water content. The hypothesis is proposed that preference hierarchies reflect relative handling times of different food types and that these fish maximize 'through-put' by preferentially consuming plant species which can be most rapidly ingested.     

Effects of temperature and stocking density on food consumption and growth of grass carp Ctenopharyngodon idella, Val.

Grass carp were raised in 227 1 indoor tanks at 12.8, 18.3, 23.9 and 29.4° C temperatures, each experimental condition received five fish. Five grass carp were also raised in a 1135 1 tank maintained at 29.4° C representing low stocking density (29.4° C-L). Food consumption, food conversion, and growth of carp were not different among the 18.3, 23.9, and 29.4° C experimental conditions with identical stocking density. The least growth and food consumption were noted for the fish at the 12.8° C temperature. The fish at the low stocking density had the best growth and maximum food consumption.     

Effect of berberine hydrochloride on grass carp Ctenopharyngodon idella serum bactericidal activity against Edwardsiella ictaluri

Bactericidal activity of grass carp (Ctenopharyngodon idella) serum was significantly enhanced when pre-treated with 15 mg l?1 or 3 mg l?1 of berberine hydrochloride, an effective component of several commonly used herbal medicines in aquaculture. The complement consumption experiment demonstrated that berberine hydrochloride can certainly activate fish complement system. The results of both experiments suggested that berberine hydrochloride could enhance the serum bactericidal activity in grass carp by activating the complement system and indicating the potential in the prevention or treatment of fish diseases.     

Aquaculture of fry and fingerling of pike-perch (Stizostedion lucioperca L.) — a short review

This review presents a short survey of pertinent literature on rearing methods of pike-perch fry and fingerlings in ponds, net cages and tanks. The traditional pond culture results in variable numbers of fingerlings, which are sometimes small and are therefore of limited value for stocking. Fingerling production can be increased by manipulating the succession of zooplankton and by stocking adequate quantities of fry in the pond. Culture in illuminated net cages in lakes seems to be a possibility to produce advanced fry. The rearing of larvae in tanks following controlled propagation is initially based on feeding natural plankton. The artificial diet can only be used successfully several weeks later at fingerling size (4–5 cm). High mortality rates of fry and symptoms of food deficiency in liver cells indicate unsatisfactory quality of larval diets tested until now. Lack of an adequate artificial feed considerably hampers further development of intensive rearing of fry. Growth of fry and fingerlings is strongly temperature dependent. Growth is rather poor at 16–18°C and best between 26–30°C. Although there is a short stage of positive phototropism in fry, older pike-perch generally prefer dim light. There is no food uptake at high light intensity and mortalities will occur under such conditions. More research is needed on adequate diets which consider the ontogenetic development of the digestive organs of young fish.     

Feeding behaviour of yearling and older hybrid grass carp

Hybrid grass carp resulting from the cross of a female grass carp, Ctenopharyngodon idella (Val.), and a male bighead carp, Hypophthalmichthys ( Aristichthys ) nobilis Rich., 12–18 months old ( c . 300 mm T.L.) were studied in a two-part experiment to determine feeding preference and total daily consumption fish^-1 on selected species of aquatic plants. Fish were maintained in circular pools with 6840·8 1 of water inside a temperature-controlled greenhouse. Preference tests were conducted at three temperature ranges; 25–28° C, 17–20° C and 12–15° C. Based on the time to complete consumption or the relative quantity consumed, the most preferred plant was Lemna gibba when in combination with six other species. Chara sp., Najas guadalupensis and Potamogeton peciinatus were readily consumed and considered to be of about equal preference. Ceratophyllum demersum and Myriophyllum brasiliense were least preferred. Hybrid grass carp generally consumed as much plant material species^-1 and in the same order of preference at the 12–15°C range as they did at 25–28° C. In the second part, mean daily consumption (g) fish^-1 at 25·7–31·0° C for five plant species tested separately was as follows: Chara sp. 369·8; Lemna gibba 178·2; Najas guadalupensis 172·6; Hydrilla verticillata 106·4 and Ceratophyllum demersum 8·8.     

Evaluation of the separation of triploid and diploid grass carp, Ctenopharyngodon idella (Valenciennes), by external morphology

The external morphology of diploid and triploid grass carp was studied to determine whether the two types could be separated by differences in external characteristics. In a comparison of 27 measurements, six scale counts and five fin formulae from two stocks of diploid and triploid fish obtained from commercial producers, analysis of covariance and discriminant analysis indicated a classification accuracy of only 65–85%. Clearly, triploid grass carp differentiated by external morphology alone should not be stocked into waters where diploid fish are illegal or would cause management problems.     

二龄草鱼脾脏、肝脏组织高表达甘露糖结合凝集素mRNA

Innate immunity is expected to be very important in fish. Mannose-bingding lectin (MBL) participates in the innate immune system as an activator of the complement system and as an opsonin after binding to certain carbohydrate structures on microorganisms. In this experiment, total mRNA was isolated from spleen, liver, gills, thymus, head kidney and kidney of adult and immature grass carp Ctenopharygodon idllus. The cDNA of MBL was obtained by RT-PCR using total mRNA from the spleen of carp as template. Such cDNA was labled with ^32p and used as probe for Northern analysis, and autoradiographic signals were quantified by densitometry analysis. The results showed that MBL was high expressed in the spleen and liver and low in gills, thymus, head kidney and kidney of adult grass carp, and MBL was much lower expressed in spleen and liver of immature grass carp than those of adult grass carp. The results might partially explain why immature grass carp are vulnerable to grass carp hemorrhage virus (GCHV) whereas adult grass carp are not.This suggested that MBL mav be an imoortant anti-GCHV factor [Acta Zoologica Sinica 50 (1): 137 - 140. 2004].     

Larval rearing of fringe-lipped carp,Labeo fimbriatus (Bloch) with low cost diets including green bottle fly Lucilia sericata (Meigen) larvae meal incorporated diet

A study was conducted with non-conventional ingredients to test their efficacy as fishmeal (FM) replacers in the diet of fringe- lipped carp. Labeo fimbriatus first feeding larvae and fry were reared for 30 and 60 days in indoor, 50 L, aerated, circular plastic tanks at 100 and 30 numbers tank⁻¹, respectively. In the first feeding larvae to fry rearing experiment (Exp. 1), the fish were fed with either of the following isonitrogenous and isocaloric diets – live plankton, FM diet, green bottle fly (Lucilia sericata) larvae meal (GBFLM) diet and silkworm pupa (SWP) diet. The fry to fingerling rearing (Exp. 2), was also conducted using the same diets described above except live plankton. All compounded diets were formulated to contain 40% crude protein for the experiment 1 and 35% for experiment 2 and were fed ad libitum. Triplicate tanks were maintained for each treatment in both the experiments. In Exp. 1, the mean final weight of fry was higher with plankton and FM diets, while no difference (p > .05) was observed between FM and GBFLM diets. Weight of fish fed SWP diets was not statistically different from those fed GBFLM diet. No difference (p > .05) in final length, survival and condition factor was recorded. Analysis of digestive enzyme activity of whole fish revealed lower (p < .05) activity of amylase in fish fed plankton. In Exp. 2, no difference (p > .05) was observed between the different diet groups in terms of mean final weight, length, survival and condition factor. Analysis of digestive enzyme activity of whole fish revealed no difference (p > .05) in the activity of digestive enzymes between the treatments except a lower (p < .05) activity of trypsin in FM diet and lipase in FM and GBFLM diets. Since the survival and condition factors of animals is the most important aspect during nursery rearing, similar (p > .05) values recorded in different treatments indicate the possibility of incorporation of these non-conventional protein sources in the diet of L. fimbriatus during first feeding larvae to fry and fry to fingerling rearing.     

Food consumption, growth and survival of grass carp Ctenopharyngodon idella Val at four salinities

Grass carp were raised in 227-1 indoor tanks at 3,5,7 and 9%osalinities and 18·5 and 29·5°C temperatures at a density of five fish per tank. Growth rate did not differ under these conditions. Food consumption was similar between temperatures at a given salinity but differed among the salinities with most food intake at the 5%o salinity. An average of 40% of grass carp survived for 180 or more days.     

Evaluation of sugarcane by-product pressmud as a manure in carp culture

The effectiveness of pressmud, a sugarcane by-product, was tested as a manure in the production of natural food and carp, by conducting two experiments. The first experiment, of 5 weeks duration, examined the effect of pressmud addition on water quality and natural food production. This study was carried out in fibreglass tubs (1.54 m3) with a 5 cm mud layer, employing pressmud at dosages of 5000, 10,000 and 15,000 kg ha(-1) for treatments T1, T2 and T3, respectively. Unfertilized tubs served as control (T0). The second experiment of 120-day duration to study the effect on growth, survival and quality of common carp was conducted in 25 m2 cement tanks with 15 cm-mud bottom, using the same dosages of pressmud. The control tanks in this experiment were manured with cattle dung at 10,000 kg ha(-1) (T0). Application of pressmud enhanced (P < 0.05) natural food production, with the greatest effect noted in treatment T3. Fish growth was significantly greater (P < 0.05) in treatments T2 and T3, there being no difference in growth between the control (T0) and 5000 kg pressmud treatment (T1). The greatest survival and production were obtained under treatment T2, which indicates that the dosage of 10,000 kg ha(-1) pressmud is optimal for carp culture. A significant effect (P < 0.05) of pressmud on carcass protein was observed. Organoleptic quality of both raw flesh and cooked meat of carp was not affected (P > 0.05) by pressmud treatment.     

High-level expression, purification, and characterization of the recombinant grass carp pituitary adenylate cyclase-activating polypeptide

Pituitary adenylate cyclase-activating polypeptide-38 (PACAP(38)) is a potent secretagog for growth hormone and gonadotropin in fish species. To obtain recombinant grass carp PACAP(38), its open reading frame was subcloned in pET32a(+) vector to express thioredoxin (Trx)-PACAP fusion protein in Escherichia coli BL21 (DE3). The resulting expression level of the thioredoxin-PACAP reached 36% of the total proteins, and more than 85% of fusion protein existed as soluble form. Using Ni(2+)-chelating affinity chromatography, 102 mg of Trx-PACAP(38) with a purity of 97% was obtained from 342 mg of crude proteins from a 1-liter culture of Escherichia coli. The purified Trx-PACAP specifically inhibited T98G human glioblastoma cell proliferation, but the fusion partner had no effect in this regard. Moreover, this inhibition was totally abolished by PACAP-specific antibody.     

草鱼种无机盐需要量之研究

应用正交法设计进行了三批草鱼种对钙、磷、镁、铁等无机盐元素需要量饲养试验.在此基础上又设计进行了两批以三池平行为一组的鉴别试验.经数理统计分析,获得了草鱼种饲料适宜混合无机盐含量,草鱼种对钙、磷等13种无机盐元素的适宜需要量,以及适宜比例.取得了比哈尔佛Halver氏鱼类营养盐(美国药典U.S.P.Ⅻ.No.2营养盐加哈尔佛微量元素)更适于草鱼种生长需要的新型混合无机盐.试验表明,对草鱼种生长影响比较大的无机盐元素是钙、磷、铁、硫、镁和钴.适宜的混合无机盐对草鱼种生长具有显著的促进作用,不适宜的混合无机盐或缺乏无机盐则草鱼种食欲差,生长缓慢,蛋白质效率低,出现营养缺乏症状.草鱼种对无机盐的需要表明,它不同于已有报道的大鳞大马哈鱼、斑点叉尾鮰、虹鳟、鲤、红海鲷、日本鳗、溪红点鲑,以及非鲫等.所作鱼体背肌、脊柱和血液的生化成分分析表明,第四、五批试验所养草鱼种与常规用草饲养的草鱼种基本一致.       

The grass carp for weed control

The agricultural and recreational use of waterways is decreased by a too luxurous growth of various species of aquatic plants. Weed control has to be carried out at least once every year. The old-fashioned hand-cutting has nearly been abandoned, due to shortage of manpower and high costs. For the same reasons mechanical weed control methods are not very popular everywhere. Possibilities for chemical control of aquatic weeds in Dutch waterways are restricted.The grass carp (Ctenopharyngodon idella) could offer an inexpensive biological alternative. Experiments showed, that this fish is an efficient weedcontrol agent under Dutch circumstances. It is presumed, that its impact on various functions of the surface water is less (or at least less rigorous) than that of modern mechanical or chemical methods. Still it is felt, that this impact (side-effects) should be investigated thoroughly before introduction of this exotic species into our aquatic environment. For this reason a Working Party was formed within the framework of the Dutch Agricultural Research Council, section Weed Research.Preliminary results indicate that the grass carp does not eradicate plant-species; in the experiments remnants of the original vegetation remained, so that recovery was possible. Furthermore the macrophytic diversity was only slightly decreased. These observations indicate that the grass carp shows very little selectivity in type of food and in space. From a biological point of view this is rather ideal for any weed control agent. Up till now no clear influence on the composition or quantity of the microflora was found.The quantity of macrofauna and macrobenthos decreased in grass carp plots, for unknown reasons, but the rate of diversity does not differ from the rate of diversity in the control plots. Influence of grass carp stocking on growth, survical and breeding of endemic fishes will be studied in the coming years.