Olive barb, Puntius sarana (Hamilton) is a potential candidate species for introduction into the grow-out carp polyculture system

The compatibility of olive barb, Puntius sarana (Hamilton) with major carps was studied in grow-out carp polyculture system for one year in a set of nine earthen ponds of 0.08 ha each. Three different species combinations evaluated were Control: catla (Catla catla Ham.), silver carp (Hypophthalmichthys molitrix Valenciennes), rohu (Labeo rohita Hamilton) and mrigal (Cirrhinus mrigala Hamilton) at 0.5:0.5:1:1; T1: catla, silver carp, rohu and olive barb at 0.5:0.5:1:1 and T2: catla, silver carp, mrigal and olive barb at 0.5:0.5:1:1 at combined density of 7500 fingerlings/ha. While survival levels of the carps did not differ significantly in treatments (P > 0.05), silver carp recorded highest survival levels (94–96%) followed by olive barb (87–90%), mrigal (72–74%), rohu (72–73%) and catla (67–69%). The specific growth rate (SGR) and average harvested body weight (ABW) of catla and silver carp did not differ significantly among the treatments revealing their competition with mrigal or olive barb to be minimum. In absence of rohu in T2, both mrigal and olive barb showed higher SGR and ABW revealing minimal competition between these two species, while their lower performance in presence of rohu in Control and T1 indicated inter-specific competition with the latter. Such olive barb–rohu inter-specific competition, however, failed to yield significant effect on growth of rohu as revealed from its non-significant SGR difference in presence and absence of olive barb. The lower FCR (2.54 ± 0.06) and higher treatment biomass production (3418.4 ± 95.0 kg ha^− 1 year^− 1) in T1 with rohu–olive barb combination compared to T2 with mrigal–olive barb (2.84 ± 0.11; 3155.1 ± 104.7 kg ha^− 1 year^− 1) indicated feasibility and advantage of culturing rohu with olive barb rather than mrigal in carp polyculture. Further, similar biomass production in Control and T1 also indicated feasibility of replacing mrigal with olive barb in the grow-out carp polyculture system.     

Genetic variations in survival of rohu carp (Labeo rohita, Hamilton) after Aeromonas hydrophila infection in challenge tests

A challenge test against Aeromonas hydrophila was conducted using 2062 rohu carp (Labeo rohita) fingerlings obtained from 52 dams and 87 sires (87 full-sib families) of two year-classes (2003 and 2004). Attempts to establish a cohabitant challenge model were not successful. Therefore, fish were challenged by intraperitoneal injection with A. hydrophila in two replicate tanks per year-class, and dead fish were collected hourly. The mortality reached its peak at 16–22 h after challenge and had almost completely stopped after 58 h. The test was terminated after 382 h at which the average survival was 43.9 and 48.9% in the two 2003 year-class tanks, and 77.1 and 35.8% in the two 2004 year-class tanks. Heritability estimates for survival were obtained from sire and dam threshold models (THR) and sire and dam linear repeatability models (LINR). For both types of models the heritability estimates based on data from single tanks were not consistent. For both year-classes, data from one of the two challenged tanks demonstrated significant additive genetic variation in survival during the A. hydrophila infection, whereas the heritability estimates were not significantly different from zero for the other tank. Further, genetic correlation between survivals in the two replicate tanks in each year-class was not significantly different from zero. The differential results from the replicate tanks demonstrate that additional challenge test experiments are needed before firm conclusions can be drawn about the magnitude of additive genetic variation for survival to aeromonasis in rohu carp. A cohabitant challenge model that allows the testing of important defence mechanisms in the skin and mucous membranes of the fish might have been more appropriate. To establish a valid cohabitant challenge model for rohu carp should be given high priority.     

Autoregressive technique in length growth modelling of two Indian major carp, Catla catla (Hamilton) and Labeo rohita (Hamilton), reared under two holding conditions

An autoregressive analysis was performed on data from an investigation of the velocity and acceleration of the day-to-day length increments of two Indian major carp, Catla catla (Hamilton) and Labeo rohita (Hamilton), hatched in artificial (Chinese-style hatchery) and semi-natural (improvised pits) holding conditions. The autoregressive model, which was capable of providing short- and long-term predictions, was tested in parallel with a time regressive model and an instantaneous growth rate model. The estimate simulating short-term predictions was found to describe the data more efficiently than the other estimates of the models. Product-moment correlations comparing the two holding systems revealed no source-specific variation of growth between the species. However, the significant length velocity correlation suggests that the artificial system has greater efficacy.     

黄河鲤酪氨酸酶基因的克隆、表达模式及定位分析

为探究Tyrosinase(Tyr)基因在黄河鲤体色形成中的作用,利用生物显微镜对黄河鲤黑色鳞片、银色鳞片、鳍条色素细胞的组成进行观察,并利用RACE克隆黄河鲤Tyr基因全长cDNA序列,荧光定量PCR分析其在不同组织中的表达情况,Western blot印迹和免疫组织化学方法检测其蛋白的表达定位。结果显示,黄河鲤具有黑色素细胞、黄色素细胞和虹彩细胞3种色素细胞,3种色素细胞的数量、种类和分布在不同组织中存在较大差异。黄河鲤Tyr基因cDNA全长1717 bp(GenBank ID:No.KY305667),其中ORF长1605 bp,编码535个氨基酸,5′-UTR区41 bp,3′-UTR区71 bp。蛋白同源分析发现,黄河鲤Tyr与鲤科鱼类相似性最高,与哺乳类及鸟类等脊椎动物相似性最低。系统进化分析显示,黄河鲤Tyr与鲤、瓯江彩鲤、锦鲤和斑马鱼等鲤科鱼类的亲缘关系最近。实时定量PCR分析表明,Tyr基因在黄河鲤不同组织中均有表达,肌肉中的表达量最高,其次是黑色皮肤,另外在黄色皮肤、臀鳍和尾鳍等黑色素细胞存在的组织中也有较高表达。Western blot印迹结果显示,Tyr基因在黑色皮肤中表达最高,其次是臀鳍和尾鳍,银色皮肤中没有表达。免疫组织化学结果显示,Tyr基因在黑色皮肤的黑色素细胞和黏液细胞中有表达。研究表明,Tyr基因表达水平与黑色素细胞数量和分布具有一定相关性,参与黄河鲤体色的形成。     

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.     

Age and growth of the largemouth perch Percichthys colhuapiensis in the Negro river, Argentine Patagonia

Largemouth perch (Percichthys colhuapiensis) represents one of the most economically important fish species in the Argentine Patagonia. However, little research has been done on the age and growth and population dynamics of this fish, though both studies are essential to properly deal with fisheries forecasts and management. As a contribution to elaborating management programmes for P. colhuapiensis, we evaluated the age and growth of this species in the Negro river via scale and whole otolith reading methods. The sample consisted of 579 specimens ranging in total length (TL) from 90 to 475 mm, captured seasonally from December 1994 to December 1995. The formation of scale annuli (end of winter) and the hyaline zone on otoliths (winter) of adult fish coincided with the beginning of the spawning season (end of winter-beginning of spring). The maximum estimated age was 11 years, which indicates that this is a relatively long-lived species. Otoliths were useful for ageing specimens 1–5 years-old, but above this age whole otoliths yielded lower age estimates than scales. Isometric growth of weight with length was found for total population, juveniles, and separate sexes (p > 0.25 in all cases). No significant differences between the length–weight relationships of sexes were observed (p > 0.10). Length at first maturity was significantly higher for males (TL₅₀ = 271 mm TL; r = 0.88) than for females (TL₅₀ = 243 mm TL; r = 0.96) (p < 0.01). Largemouth perch exhibited a consistent pattern of increase in length with age, with a period of fast growth during the first 5 years, and a slow-growing phase during the rest of his life. The growth parameters based on scale data were L∞: 462.1 mm, k = 0.23 and t₀ = −0.94 for total population, L∞: 402.3 mm, k = 0.33 and t₀ = −0.67 for males, and L∞: 548.4 mm, k = 0.15 and t₀ = −1.59 for females, whereas those based on otolith reading were L∞: 537.4 mm, k = 0.17 and t₀ = −1.0 for total population, L∞: 497.6 mm, k = 0.21 and t₀ = −0.79 for males, and L∞: 582.0 mm, k = 0.14 and t₀ = −1.53 for females. Scales are concluded to be the best structure to age P. colhuapiensis because they rendered L∞ values closer to the maximum TL observed, high precision, easiness of collection, low processing time, and the possibility of performing non-destructive monitoring studies.     

Precision of age estimates derived from scales and pectoral fin rays of blue sucker

Abstract Evaluating the response of fish populations to environmental influences requires precise age estimation. Pectoral fin rays and scales were compared to determine which is more precise for estimating age of blue sucker, Cycleptus elongatus (Lesueur), from the Missouri River, USA. Mean coefficient of variation was significantly lower for fin rays both among three novice readers (rays 19.9%; scales 23.1%) and among three reads by a single experienced reader (rays 11.8%; scales 18.6%). Additionally, exact per cent agreement (rays 20.0%; scales 14.3%) and within‐1‐year per cent agreement (rays 89.1%; scales 73.9%) were higher for fin rays compared with scales for multiple reads by the same experienced reader. Age–bias plots revealed that scale ages were lower than fin‐ray ages >7. The use of fin rays is recommended for estimating ages of blue sucker until validation procedures are conducted.     

The effect of common carp, Cyprinus carpio (L.) and mrigal, Cirrhinus mrigala (Hamilton) as bottom feeders in major Indian carp polycultures

A polyculture experiment with the large carp rohu, Labeo rohita (Hamilton), catla, Catla catla (Hamilton) and either mrigal, Cirrhinus mrigala (Hamilton) or common carp, Cyprinus carpio (L.) (as cash crop fish), and the small indigenous fish punti, Puntius sophore (Hamilton) (as food for the small‐scale farmer family) was carried out at the Field Laboratory of the Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh. The main objective was to compare polycultures of large carp in which the bottom feeder is either the native mrigal or the exotic common carp. Secondary objectives were to assess the effects of adding the small indigenous species punti to polycultures of large carp, and to compare the effects of mrigal and common carp on punti production and reproduction. It was found that (i) common carp damaged embankments, had no effect on catla, improved rohu performance by 50% and total fish production by 20%; (ii) punti addition did not affect rohu, catla and total yield, improved mrigal performance by 50%, and decreased common carp performance by 20%; and (iii) punti was not affected either by common carp or by mrigal. However, its performance was not satisfactory, probably owing to frequent netting, which might have hindered growth and breeding. In spite of the embankment damage caused by common carp, this bottom feeder seems to be more promising than mrigal, because it leads to higher fish production. The addition of punti to the large carp polyculture is a viable proposition, as it does not reduce cash crop production, and might be a good food source for a small‐scale farmer's family.     

Effect of dietary vitamin A on Senegalese sole (Solea senegalensis) skeletogenesis and larval quality

The effects of different levels of vitamin A (VA) in Senegalese sole larval performance and development were evaluated by means of a dietary dose–response experiment using enriched Artemia metanauplii as a carrier of this micronutrient. Larvae were fed from 6 to 27 days post hatch (dph) with enriched Artemia containing graded levels of total VA (1.3, 2.1, 4.5 and 12.9 µg VA mg^− 1 DW). The content of VA in live prey directly affected its accumulation in larvae and early juveniles. Retinyl palmitate accumulated during larval ontogeny, whereas retinol showed the opposite trend, decreasing from hatching until 41 dph and then remaining constant until the end of the study.In metamorphic larvae (10 and 15 dph), VA did not affect the number of thyroid follicles or the intensity of the immunoreactive staining of T₃ and T₄. However, at older stages of development (post-metamorphic larvae: 20, 30, 41 and 48 dph), VA decreased the number of thyroid follicles but increased their mean size and enhanced T₃ and T₄ immunoreactive staining. A dietary excess of VA did not affect either larval performance in terms of growth and survival or the maturation of the digestive system. However, the most remarkable impact of this morphogenetic nutrient was detected during skeletal morphogenesis. Dietary VA accelerated the intramembranous ossification of vertebral centrums, which led to the formation of a supranumerary haemal vertebra and a high incidence of fused and compressed vertebrae in fish fed 2.1, 4.5 and 12.9 mg VA mg^− 1 DW. In addition, VA also affected those structures from vertebrae and caudal fin formed by chondral ossification, leading to defects in their shape and fusions with adjacent skeletal elements. In particular, the caudal fin was the region most affected by the dietary treatments. In order of importance, the bones with more developmental anomalies were the modified neural and haemal spines, epural, hypurals and parahypural. The impact of systemic factors such as thyroidal hormones in skeletogenesis should not be neglected since present results revealed that an excess of dietary VA affected the levels of T₃ and T₄, which might have affected bone formation and remodelling, leading to skeletal deformities.     

Biological parameters of the bathyal fish black scabbardfish (Aphanopus carbo Lowe, 1839) off the Canary Islands, Central-east Atlantic

The main biological characteristics for black scabbardfish in the Canary Islands waters were established, focusing on its reproductive behaviour and strategy and its growth pattern. The sex proportion differs significantly from the 1:1 ratio, being clearly unbalanced towards the females. The sex ratio according to depth clearly shows the presence of male and female individuals in all the studied layers, thus sex segregation does not happen according to depth. The Canaries can be considered to be a reproduction site for A. carbo, since samples showing all stages of maturity have been observed. The gonadosomatic index (GSI) showed that the mean values were higher in the third and fourth quarters of the year. The index values clearly allow the differentiation of the individuals in resting or in spent (II and V) stages from individuals in ripe or in ripe and running stages, indicating that index levels higher than 2 are typical of maturation followed by spawning process. Up to twelve marks, assumed to be annuli, were visible in the sampled otoliths. Three to five years old were the dominant age classes and only 7.7% of fish were 7 years old or older. Age estimates ranged between 2 and 8 years for males and between 2 and 12 years for females. Estimated growth parameters were: L_∞ = 1477 ± 18.73 mm; k = 0.200 ± 0.016 year⁻¹; and t₀ = −4.58 ± 0.413 year. Biological aspects of the black scabbardfish suggest that this species has a generalist life-history strategy.     

Effects of experimental infection by Caligus rogercresseyi (Copepoda: Caligidae) on the common jollytail, Galaxias maculatus (Osmeriforme: Galaxiidae) (Jenyns, 1842) in Chile

Galaxias maculatus, the common jollytail, is a native smelt fish with a lacustrine or diadromous life cycle. In Chile, the rearing cycle of this fish includes a freshwater and a marine phase. Several diseases and parasites reported for the freshwater phase could be avoided by rearing the fish in salty or brackish water. Nonetheless, this alternative could result in Caligus rogercresseyi infections. The objective of this study was to evaluate experimentally the capacity of C. rogercresseyi to infect the common jollytail and the effects this parasite may cause to the fish. Prevalence and intensity of experimental C. rogercresseyi infections on G. maculatus were estimated and the effects of this parasitosis on the fish were evaluated on fish survival, weight loss, swimming behavior, and skin damage. Two experiments were carried out with adult fish taken from the Maullín Estuary. Fish were acclimatized to a salinity of 32 ppt and divided into two groups of 20 fish each. The experimental group was infected with copepodid stages of C. rogercresseyi and the other was used as a control. The fish were kept in individual tanks until observing ovigerous female copepods. C. rogercresseyi recognizes G. maculatus as a host under experimental conditions and optimal salinity for the parasite. Results show that under experimental condition copepodid stage can successfully infect the fish, developing to the adult stage, mating, and producing eggs (females). C. rogercresseyi caused alterations in fish behavior, superficial body damage, weight loss, and mortality. Rearing the common jollytail in salty water should take into consideration measures to control these infections as they can damage fish and affect surrounding wild fish populations. There are no records of this parasite in natural common jollytail populations; however, our understanding of the ecological role played by the common jollytail in C. rogercresseyi transmissions among sympatric host species could be greatly improved through further research related to host preferences and epidemiological data for different sympatric host species.     

Effect of a probiotic bacterium <Emphasis Type="Italic">Bacillus circulans</Emphasis> PB7 in the formulated diets: on growth,nutritional quality and immunity of <Emphasis Type="Italic">Catla catla</Emphasis> (Ham.)

Bacillus circulans PB7, isolated from the intestine of Catla catla, was evaluated for use as a probiotic supplement in the feeds for the fingerlings of Catla catla. The effect of supplement on the growth performance, feed utilization efficiency, and immune response was evaluated. Catla fingerlings (ave. wt. 6.48 ± 0.43 g) were fed diets supplemented with 2 × 10⁴ (feed C1), 2 × 10⁵ (feed C2), and 2 × 10⁶ (feed C3) B. circulans PB 7 cells per 100 g feed for 60 days at 5% of the body weight per day in two equal instalments in triplicate treatments. The control feed (CC) was not supplemented with the B. circulans. All the feeds were isocaloric and isonitrogenous. Fish fed with feed C2 displayed better growth, significantly (P ≤ 0.05) highest RNA/DNA ratio, a lower feed conversion ratio (FCR), and a higher protein efficiency ratio (PER) than the other experimental diets. Highest carcass protein and lipid was also observed in the fish fed C2 feed compared to the others. Significantly (P ≤ 0.05), highest protease was recorded in fish fed feed C2 (47.9 ± 0.016) and lowest in fish fed feed C3 (32.10 ± 0.009), where α-amylase activity did not differ significantly (P ≤ 0.05) beyond the lowest inclusion level. ALP, ACP, GOT, and GPT in the liver of Catla catla were the highest (P ≤ 0.05) in fish fed C2 feed. The highest TSP, albumin, and globulin was observed in fish treated with C2 feed after 60 days feeding trial, but the lowest glucose level was observed in the same treatment. After the feeding trial, the non-specific immunity levels and disease resistance of fish were also studied. Phagocytic ratio, phagocytic index, and leucocrit value were the highest in fish fed feed C2. After the feeding trial, the fish were challenged for 10 days by bath exposure to Aeromonas hydrophila (AH1) (10⁵c.f.u. ml⁻¹ for 1 h, and, after 7 days, 10⁷c.f.u. ml⁻¹ for 1 h). Highest survival percentage was observed in fish fed with feed C2 compared with only 6.66% in the controls, which indicated the effectiveness of B. circulans PB 7 in reducing disease caused by A. hydrophila.     

Dietary Houttuynia cordata leaf extract and meal enhances the immunity and expression of immune genes in Labeo rohita (Hamilton, 1822)

A feeding trial was conducted to explore the effect of dietary Houttuynia cordata leaf extract (HCLE) and leaf meal (HCLM) on immunological responses and expression of interferon‐gamma (IFN‐γ) and tumour necrosis factor‐alpha (TNF‐α) gene in Labeo rohita fingerlings. Six isonitrogenous (350 g/kg CP) and isocaloric (17 MJ/kg DE) purified experimental diets were formulated with Houttuynia cordata leaf extract and leaf meal comprising control, C (0 g/kg HCLE and HCLM), E2.5 (2.5 g/kg HCLE), E5 (5 g/kg HCLE), E10 (10 g/kg HCLE), M10 (10 g/kg HCLM) and M20 (20 g/kg HCLM). Labeo rohita fingerlings (3.37 ± 0.23 g) were distributed in six experimental groups in triplicates following the complete random distribution. Fish were fed twice daily with respective experimental diets for a period of 60 days. A significantly (p < .05) lower lactate dehydrogenase, malate dehydrogenase, superoxide dismutase and catalase activities were registered in supplemented groups compared with control group, while respiratory burst and lysozyme activities were significantly (p < .05) higher in E10 group compared with other experimental groups. Haemoglobin, total leucocyte count, total erythrocyte count and haematocrit values were significantly (p < .05) higher in E10 group. The expression of IFN‐γ and TNF‐α in both the kidney and liver was significantly up‐regulated in leaf extract and meal supplemented groups with the highest expression in the fish of E10 group. Overall, these results suggest that the dietary supplementation of ethanolic extract of the Houttuynia cordata leaf at 10 g/kg level can enhance the immune response of L. rohita fingerlings.     

黄颡鱼不同组织矿物元素的分布及含量

为了探究鱼类不同组织中矿物元素的含量，实验以养殖黄颡鱼为对象，采用电感耦合等离子体质谱法测定了黄颡鱼18个组织(心脏、肝脏、脑、脾脏、肾脏、肌肉、脂肪、前肠、中后肠、眼睛、鳃、尾鳍、鱼鳔、骨骼、胃、皮肤、血液、全鱼)中7种矿物元素(Ca、Mg、Zn、Fe、Cu、Mn和Se)的含量与分布。结果显示，Ca在骨骼、鳃、尾鳍和肌肉中占比较高，在尾鳍和骨骼中含量最高，在脂肪组织中含量最低；Mg在骨骼和肌肉中占比较高，在骨骼和尾鳍中含量最高，在眼睛中含量最低；Zn在骨骼、肌肉、皮肤和眼睛中占比较高，在眼睛中含量最高，在脂肪组织中含量最低；Fe在骨骼、血液和肌肉中占比较高，在血液中含量最高，在脂肪组织中含量最低；Cu在骨骼、肌肉和肝脏中占比较高，在肾脏和肝脏中含量较高，而在脂肪和眼睛中含量最低；Mn在骨骼和肌肉中占比较高，在骨骼和尾鳍中含量较高，在眼睛和脂肪中含量较低；Se在肌肉、骨骼、皮肤和肝脏中占比较高，在脾脏、肝脏、肾脏和前肠中含量较高，在肌肉和脂肪中含量较低。研究表明，黄颡鱼体内含有丰富的矿物元素(Ca、Mg、Zn、Fe、Cu、Mn、Se)，而且在不同组织中具有不同的分布特征。研究采用ICP...     

锦鲤墨蝶呤还原酶基因的克隆、表达和定位分析

为探究SPR在锦鲤体色形成中的作用,实验利用RACE技术获得spr cDNA全长序列,并分析其时空表达模式,同时利用Western blot和免疫组织化学方法检测SPR蛋白在皮肤、鳍条和鳞片中的分布和表达情况。结果显示,spr cDNA全长879 bp,包含132 bp和134 bp的5′和3′非编码区,开放阅读框510 bp,编码170个氨基酸残基。氨基酸序列比对和系统进化树分析显示,锦鲤SPR具有保守的adh_short_C2结构域,与金鱼相似性高达97.7%。spr在各组织中均有表达,其中皮肤的表达量最高。spr在锦鲤个体发育的4个阶段表现为先降后升。纯红、纯白及红白3种体色锦鲤皮肤、鳞片和鳍条中spr mRNA和蛋白表达水平基本一致,在纯红锦鲤皮肤中表达量最高,红白锦鲤白色皮肤、鳞片和鳍条的表达量最低。SPR组织定位分析显示,红色锦鲤和白色锦鲤皮肤中均检测到阳性信号,其中红色皮肤阳性信号强度高于白色皮肤。研究表明,spr可能与锦鲤红/黄色素细胞的分化和形成具有一定相关性,参与了锦鲤体色的形成。     

Use of vitamin C as an immunostimulant. Effect on growth,nutritional quality,and immune response of <Emphasis Type="Italic">Labeo rohita</Emphasis> (Ham.)

Teleost fish lack the enzyme for endogenous synthesis of ascorbic acid (AA), an essential micronutrient for fish. The aim of this study was to examine the effect of higher levels of dietary vitamin C on growth, nutritional quality, and immunomodulation in the Indian major carp, rohu (Labeo rohita). Four groups of L. rohita were fed experimental diets containing either no vitamin C (control) or supplemented with vitamin C at 500 mg kg⁻¹ (Exp-1), 1000 mg kg⁻¹ (Exp-2), or 1500 mg kg⁻¹ (Exp-3) for 60 days. Growth parameters (NWG, ADG, and SGR), serological parameters (TSP, TSA, TSG, and A:G), haematological parameters (TLC, TEC, Hct, MCV, and MCH), and different non-specific immunological parameters (PR, PI, respiratory burst activity, and bactericidal activity) were evaluated during the experimental trial. Fish fed a vitamin C-supplemented diet showed higher specific growth rate (SGR) up to 1000 mg kg⁻¹ compared with control fish. Different haematological and serological parameters along with non-specific immune parameters were influenced by vitamin C supplementation. Among the non-specific immune parameters phagocytic activity (PR and PI) and respiratory burst activity (NBT cells) were significantly (P ≤ 0.05) enhanced by increasing doses of vitamin C supplementation. Higher levels of dietary vitamin C significantly (P ≤ 0.05) enhanced protection against Aeromonas hydrophila (AH1) infection compared with controls. Results from this study help to establish the beneficial effect of vitamin C on growth and immunmodulation in rohu (L. rohita).     

Dietary Phosphorus Requirement of Fingerling Indian Major Carp,Labeo rohita (Hamilton)

Dietary phosphorus requirement of fingerling Labeo rohita (6.1 ± 0.13 cm; 1.88 ± 0.05 g) was quantified by feeding seven isonitrogenous (350 g/kg crude protein) and isocaloric (16.72 kJ/g gross energy) purified diets with different levels of phosphorus as 3.5 (basal diet), 4.6, 5.7, 6.5, 7.8, 8.9, and 10.1 g/kg. Triplicate groups of fish were fed at 0800, 1200, and 1600 h to apparent satiation for 8 wk. Live weight gain (LWG; 494.68%), specific growth rate (3.18%/d), feed conversion ratio (1.54), feed efficiency (0.65), protein gain (PG; 1.26 g/fish), protein efficiency ratio (1.86), and phosphorus utilization efficiency (98.78%) improved significantly (P < 0.05), with increasing dietary phosphorus level up to 6.5 g/kg. However, phosphorus contents of vertebrae and scale increased significantly up to 7.8 g/kg. Dietary phosphorus levels significantly affected serum phosphorus concentration and alkaline phosphatase activity. Broken‐line analysis based on LWG; PG; and whole‐body, vertebrae, and scale phosphorus against dietary phosphorus indicated the optimal phosphorus requirement of fingerling L. rohita at 6.56, 6.58, 6.56, 8.02, and 8.44 g/kg diet, respectively. In order to restrict superfluous phosphorus in the diet, inclusion of 6.56 g/kg phosphorus is recommended for optimal growth of fingerling L. rohita.     

Effect of ration size on growth,body composition,and energy and protein maintenance requirement of fingerling Indian major carp, <Emphasis Type="Italic">Labeo rohita</Emphasis> (Hamilton)

An eight-week feeding trial has been conducted to determine the optimum ration for Indian major carp, Labeo rohita, fingerling (4.10 ± 0.30 cm, 0.55 ± 0.16 g) by feeding a purified diet (40% CP; 3.61 kcal g⁻¹ GE) at six levels, 2, 4, 6, 8, 10, and 12% of body weight per day, at 0800 and 1600 h, in triplicate, to 20 fish per trough fitted with a water flow-through system. Highest weight gain, best feed conversion ratio (FCR), best specific growth rate (SGR%), and highest protein efficiency ratio (PER) were evident for rations of 6–8% body weight. Second-degree polynomial regression analysis for FCR, PER, protein, and energy retention data indicated the break-points occurred at 6.55, 6.75, 6.80, and 6.95% bw per day, respectively. Significant (P < 0.05) differences between body composition were observed for fish fed different rations. Maximum body protein content was recorded for 6% and 8% rations. A linear increase in body fat content was evident with increasing ration. Body moisture and ash content remained non-significantly (P > 0.05) low for higher rations, however. On the basis of these results it is recommended that feeding in the range 6.5–7.0% bw per day corresponding to 2.6–2.8 g protein and 23.49–25.31 kcal energy per 100 g of the diet per day is optimum for growth and efficient feed utilization of Labeo rohita. Results for 2–4% rations (0.8–1.6 g protein and 7.23–14.46 kcal energy) suggest these amounts approximate to the maintenance requirement of this fish.     

Molecular evidence for the lack of transmission of the monogenean Sparicotyle chrysophrii (Monogenea, Polyopisthocotylea) and isopod Ceratothoa oestroides (Crustacea, Cymothoidae) between wild bogue (Boops boops) and cage-reared sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax)

In the Mediterranean area, wild fish have often been suggested as either the reservoirs of the causative agents or at least the carriers of the pathogens responsible for disease outbreaks in cultured fish. However, no epidemiological investigations on actual pathogen/disease interactions between farmed and wild fish have been conducted even for the most important fish pathogens. Only sporadic isolations and identifications of various pathogens in wild fish have been done and real associations with the pathological conditions that exist within the farm environment and vice versa have not been established. Monogenean ectoparasite Sparicotyle chrysophrii and isopod Ceratothoa oestroides are commonly found in the Mediterranean cage-reared sea bream and sea bass and in the surrounding wild fish population. Both species were recognized as pathogens that seasonally inflict serious losses in fingerlings and juveniles of sea bream and sea bass, being potentially propagated and exchanged during wild and caged fish interaction. In order to evaluate the degree of pathogens transfer between wild and farmed fish, we investigated genetic population structures of these two important parasitic pathogens inferred by mtDNA cytochrome oxidase I locus. Parasites isolated from wild and farmed fish on the two most productive Adriatic fish farms showed genetic heterogeneity, contradicting widely accepted hypothesis of cross-contamination, at least in case of S. chrysophrii and C. oestroides. As far as we know, this is the first report that in a study of pathogen transfer molecular evidence was employed to asses the genetic population structure of shared parasites.     

Comparison of pelvic fin rays, scales and otoliths for estimating age and growth of bull trout, Salvelinus confluentus

Abstract  The suitability of three anatomical structures to determine age and growth of bull trout, Salvelinus confluentus (Suckley), was assessed. Scales and pelvic fin rays collected from recaptured bull trout 96–265 mm TL were used to validate annulus formation and assess the accuracy and precision of back calculation. Ageing precision and agreement of assigned ages were compared among scales, fin rays and otoliths from bull trout 52–711 mm TL. Annulus formation was validated for 88% (14 of 16 fish) of recaptured bull trout using pelvic fin rays and 68% using scales (15 of 22 fish). Annulus formation in fin rays occurred between late April to early June, and the hyaline (non-growth) band began forming in late August. Back-calculated length was not significantly different from measured length at initial capture either for fin rays or scales ( P  ≥   0.19), and absolute percent error was 7.2 ± 1.2 (mean ± SE; n  =   14) for fin rays and 8.7 ± 1.9 ( n  =   15) for scales. Consistency of back-calculated lengths at age between tag and recapture samples for individual fish was similar for fin rays (mean absolute difference = 8.2% ± 0.9; n  =   33) and scales (9.4% ± 1.4; n  =   40). However, fin rays (87% precision) and otoliths (90%) provided notably higher ageing precision than scales (68%) and closer agreement of assigned ages, particularly for fish older than age 4. Pelvic fin rays appear to offer more accurate and precise age and growth determinations than scales and a non-lethal alternative to otoliths, but further work is needed to validate the accuracy and precision of ageing large, migratory bull trout.