The Scale‐up of Spotted Rose Snapper,Lutjanus guttatus,Larval Rearing at Mazatlan,Mexico

The scale‐up of spotted rose snapper, Lutjanus guttatus, larval rearing is described. Fertilized eggs (480,000) were obtained from a 1‐d harvest of a natural spawning captive broodstock acclimatized for 1 yr and 6 mo in two fiberglass tanks (18 m³). Fourteen hours after spawning, 89.6% of the collected eggs were floating, of which 96.2% were transparent with live embryos. Incubation at 25–26 C lasted 21 h, with 90.2 ± 2.1% hatching percentage of normal larvae. The percentage of viable larvae at 48 h after hatching was 79.7 ± 1.9%. Initial stocking density was 10.4 ± 1.0 larvae/L 2 days after hatching (d.p.h.). A total of 22,600 juveniles (1256 ± 170 juveniles/m³) were harvested from six 3‐m³ cylindrical fiberglass tanks. Average survival was 12.1 ± 1.1%. Final mean length and weight were 5.5 ± 0.05 cm and 2.24 ± 0.04 g, respectively. Growth expressed in total length was TL = 2.1476e^0.0543t (R² = 0.9911). Final mean biomass and condition factor were 2.8 kg/m³, 12.3% and 1.346. General length‐weight ratio was W = 0.05460 LT^2.2306.     

Growth, Survival, and Feed Conversion Rates of Hatchery-Reared Mutton Snapper Lutjanus analis Cultured in Floating Net Cages

Abstract.— The aquaculture performance of mutton snapper Lutjanus analis raised in floating net cages was assessed by measuring their growth, survival, and feed conversion rates during a growout trial conducted in a 3.2‐ha saltwater lake in the Florida Keys, Florida, USA. Approximately 10,500 hatchery‐reared finger‐lings were stocked in two circular, high‐density polyethylene (HDPE) net cages of 7‐m diameter × 7‐m deep (300 m²) and 10‐m diameter × 7‐m deep (600 m³) dimensions. Cages were stocked at 25 fish/m³ (3.2 kg/m³) and 5 fish/m³ (0.72 kg/m³), respectively. Fish grew from a mean of 16.5 g to 302.8 g (25.6 cm TL) in 246 days in the former cage and from a mean of 42.3 g to 245.6 g (23.8 cm TL) in 178 d in the latter cage. Growth rates in weight were best expressed by the following exponential equations: cage 1 (high stocking density): W = 20.716 e^0.0112x (r²= 0.83); cage 2 (low stocking density): W = 38.848 e^0.0118x (r²= 0.81). Length‐weight data indicate that hatcheryraised, cage‐cultured mutton snapper are heavier per unit length than their wild counterparts. There was no significant difference (P < 0.05) between the slopes of the two lines, indicating that fish in the two cages grew at the same rate. The length‐weight relationships for mutton snapper stocked in cages 1 and 2 are expressed, respectively, by the equations W = 0.000009 L ^3.11 (r²= 0.99) and W = 0.000005 L ^3.22 (r²= 0.97). Overall feed conversion rate for both cages combined was 1.4. Approximately 10% of the fish sampled exhibited some degree of deformity, particularly scoliosis. Overall survival rate was 70%. Results suggest that L. analis has potential for aquaculture development in net cage systems.     

GnRHa‐induced Multiple Spawns and Volition Spawning of Captive Spotted Rose Snapper,Lutjanus guttatus,at Mazatlan,Mexico

Sexual maturation and induced spawning treatments were carried out with captive spotted rose snapper, Lutjanus guttatus. A total of 3013 × 10⁶ eggs (64.7% were floating) were produced from eight treated females in 42 spawns induced with GnRHa implants during the course of the present study. GnRHa ethylene‐vinyl acetate copolymer effective doses were 204 ± 11 µg/kg in June 2005, and 224 ± 13 µg/kg in July 2005. General fertilization was 50.9 ± 34.5% and 12–14 h after spawning, viability of floating eggs was 90.4 ± 12.4%. Mean incubation period at 29–31 C was 18–20 h, and mean hatching was 94.4 ± 8.2% (73–100%). Newly hatched larvae were 2.18 ± 0.15 mm in total length (TL). One month after the last hormone experiment, previously GnRHa‐treated and untreated fish began spawning voluntarily. Hormone‐treated breeders had higher fecundity than untreated fish, producing 72.5 million eggs versus 13.9 million eggs for the untreated fish, over the following 11 mo. Combined data of volitional spawning for total egg fertilization, viability, hatching, and larval TL were 77.7 ± 1.8%, 90.3 ± 1.3%, 87.9 ± 2%, and 2.50 ± 0.12 mm, respectively. These results can ensure the sustainability of a commercial hatchery.     

Spontaneous Spawning of Captive Red Snapper, Lutjanus campechanus, and Dietary Lipid Effect on Reproductive Performance

Two experiments addressed the spontaneous spawning of red snapper, Lutjanus campechanus , under controlled temperatures and photoperiods and the effect of broodstock diets supplemented with oils rich in polyunsaturated fatty acids. In Experiment 1, broodfish were fed a standard diet (ST1) and one enriched with menhaden oil (ER1) over a 355-d period. ER1-influenced egg fatty acid profile, however, did not positively influence egg production. Both diets produced highly viable eggs and larvae but results varied within treatments. In Experiment 2, broodfish were fed either a standard diet (ST2) or one supplemented with oils (ER2) rich in docosahexaenoic and arachidonic acid using a 203-d cycle. Both treatments produced eggs but fertilization rates ranged 0–10%. There was no clear influence of the diets on egg fatty acid profiles. These results indicate that red snapper can spawn spontaneously in tanks under controlled environmental conditions and produce viable eggs and larvae when fed diets based on squid, shrimp, and fish. The fatty acid composition of the diets was reflected in the eggs to some degree, but the oil enrichments did not further enhance the reproductive performance and egg quality under the conditions of this study.     

Effects of Stocking Density on Growth of Tilapia nilotica Cultured in Cages in Ponds

Reported maximum carrying capacities of Tilapia nilotica reared in cages are Iow ranging from 10 to 70 kg/m³. This may be related to total numbers of caged fish reared in a body of water and not simply density per cage volume. An experiment was conducted to demonstrate such effects.
Sixteen cages in a 0.77 ha pond were stocked with T. nilotica at either 250, 500, 750, or 1,000 fish/cage for a total of 12,987 fish/ha. One cage in each of four 0.13 ha ponds was stocked with either 250 or 1,000 fish/cage for a total of 1,923 or 7,692 fish/hectare, respectively. Fish were fed a 32% protein diet at equal rates for 169 days. In the 0.77 ha pond, yield per cage was positively correlated with stocking density, while individual mean weights were negatively correlated with stocking density. However, among equal densities per cage between ponds, fish in the 0.13 ha ponds gained about 26% more than in the 0.77 ha pond. An interaction of the effects of density per cage volume and per pond area may have occurred.     

Growth of Hatchery‐reared Juveniles of the Australasian Sea Cucumber,Australostichopus mollis,Fed with Artificial and Natural Diets

Australostichopus mollis is the most common and valuable sea cucumber species on the coasts of New Zealand and southern Australia. However, information supporting the development of artificial diets to advance the aquaculture of this species is scarce. In this study, the nutrient absorption, growth, pigmentation, and survival of small (111 mg) and large (434 mg) early juveniles were measured. The juveniles were fed with mussel biodeposits (MB); a commercial hatchery diet‐powdered macroalgae (HD); and artificial diets with different protein levels, 5% (5P) and 10% (10P), respectively. During the experiment, survival was greater than 66% in all diet treatments, with the juveniles feeding actively and absorbing all major macronutrients. The small juveniles, which were starting pigmentation, had higher growth rates (0.8–2.5%/d) than the large juveniles (0.2–1.2%/d), which were completing pigmentation. Growth was higher with the MB and HD diets than with the 5P and 10P diets, which could be explained by differences in the food consumption and nutrient absorption among the diet treatments. This study shows the feasibility of developing artificial diets without depending on naturally available ingredients; however, palatability and consumption need to be improved in order to make artificial diets for this species more effective and commercially available.     

利用深水网箱和膨化饲料养殖卵型鲳鲹的生长表现

美国大豆协会与海南陵水601号网箱养殖场、海南省水产技术推广站和全国水产技术推广总站合作进行卵型鲳鲹(Trachinotus ovatus)深水网箱养殖试验。本试验的目的是利用美国大豆协会OCAT(深水网箱养殖技术)标准网箱和海水鱼膨化饲料养殖卵型鲳鲹,对于鱼类养殖和网箱性能进行评估。1材料与方法1.1网箱结构本试验用的深水网箱为美国大豆协会设计,体积为100 m3的截顶四方锥形(塔形)网箱。网箱顶部的面积为2 m×2 m,网箱底部的面积为7m×7 m,网箱垂直高度约4.5 m。网箱的框架由HDPE(高密度聚乙烯)管件构成,网箱顶部及底部的框架以直径280 mm、…     

网箱商品鲤生产动态模型的研究

本研究用4800尾建鲤分4组喂给不同配方、营养水平相近的饵料,进行了5个月的饲养及比较屠宰试验,得出网箱商品鲤鱼生长动态模型:G=1/(T·A·P·C)。按此模型结合必要的生产指标研制了一套网箱养鲤生产动态模拟程序;经中试性生产检验,该程序预测的各项生产指标与实际生产效果相近(差异均小于5.0%)。     

Effect of Stocking Density on Growth,Yield, and Costs of Producing Rainbow Trout,Oncorhynchus mykiss,in Cages

Abstract

Rainbow trout, Oncorhynchus mykiss, were raised in culture cages (1 m³) to determine the effect of stocking density on growth, survival, and percentage of market-size fish. Large fingerling rainbow trout (20-25 cm, 232 g average weight) were stocked into six cages located in a 0.4-ha pond. Two stocking densities (100 or 200 fish/cage) were used, and fish were grown for 140 days (2000-April 2001). Average total harvest weight (35.0 kg) in the low-density cages was approximately one-half the average total harvest weight (61.2 kg) in the high-density cages. Average weight gain (11.7 kg to 15.1 kg) and feed conversion (1.2 to 1.5) were also smaller for the low-density cages. Average survival was 96.7% for the low-density cages and 94.2% for the high-density cages, with the percentage of market-size fish (< 29 cm) averaging 50.3% and 52.0%, respectively. Production costs for the actual experiment and the revenues from fish sold at the end of the study were collected. An enterprise budget based on the experimental results for the two densities was developed to determine if a culture operation of this size would produce a net return. Production costs and revenues from the experiment resulted in a large negative return (-$3,124) and high breakeven price ($13.53/kg).     

Effect of Feeding Rate on Growth and Feed Conversion of Florida Red Tilapia Reared in Floating Marine Cages

An experiment was conducted to investigate growth, survival and feed conversion of Florida red tilapia reared in floating cages in seawater under different feeding regimens. Twenty-four cages (1 m³) were anchored in a sea pass on Great Exuma, Bahamas, and each was stocked with 300 juvenile, monosex males (10 g mean weight). Growth was monitored every 14 days for 84 days. Fish were fed daily a floating pelletized diet (32% protein) at 4 programed rates representing 50, 70, 90, and 110% of the estimated satiation rate, ad libitum , and by demand feeders, with each treatment comprised of 4 replicate cages.
Final mean weight was significantly lower for the 50% treatment (94.1 g) than for all other treatments (range = 121.8–155.7 g). Final mean biomass per cage ranged from 24.2 to 39.4 kg/m³, and survival ranged from 98.2 to 99.8%.
Mean specific growth rate was significantly lower under the 50% programed feeding treatment (2.42%/day) than for all other treatments (range = 3.15–3.56%/day) while feed conversion ratios (dry weight/wet weight) were significantly lower under the 50% (1.57) and 70% (1.68) programed feeding treatments than under all other treatments (range = 1.98–2.26). Thus, maximum growth was achieved at feeding rates near satiation while feed conversion was improved at lower feeding rates. Under demand feeding, growth and feed conversion were not significantly different than those of the ad libitum , 100%, and 90% treatments.     

Effects of Dietary Lipid and Energy to Protein Ratio on Growth and Feed Utilization of Juvenile Mutton Snapper Lutjanus analis Fed Isonitrogenous Diets at Two Temperatures

Growth and feed utilization of juvenile, hatchery‐reared mutton snapper Lutjanus analis (mean weight = 12.2 g) were compared for 40 d in laboratory aquaria on four isonitrogenous diets (45% crude protein) of varying lipid content (6, 9, 12 and 15%) with energy:protein ratios (E: P; kJ/g protein) of 33.9, 36.3, 38.8, and 41.2, respectively. Growth on these diets was compared under temperatures of 25 and 30 C. Final weights (Wt_r) and specific growth rates (SGR) were higher (P < 0.05) at lower dietary E: P ratios of 33.9 and 36.3 (Wt_r= 20.3–22.0 g; SGR = 1.25–1.35%/d) than at E:P ratios of 38.8 and 41.2 (Wt_r= 17.2‐17.7 g; SGR = 0.84–0.85%/d). Growth at 30 C (Wt_r= 21.5 g, SGR = 1.35%/d) was higher (P < 0.05) than at 25 C (Wt_r= 17.3 g; SGR = 0.82%/d). Feed consumption (FC) was higher (P < 0.05) at a dietary E: P ratio of 33.9 (1.57%/d) than at 36.3 (1.27%/d) or 38.8–41.2 (0.89–0.98%/d). Growth was highly correlated (P < 0.01) to E: P ratio and to feed consumption. Feed conversion ratio (FCR = 2.17–3.98), protein efficiency ratio (PER = 0.58–1.03) and apparent net protein retention (ANPR = 15.8–20.0%) were not significantly (P > 0.05) affected by dietary E: P ratio. Apparent net energy retention (ANER) was higher (P < 0.05) at E: P ratios of 33.9 and 36.3 (9.50–9.98%) than at E: P ratios of 38.8 and 41.2 (7.15–7.10%). Feed utilization parameters were significantly (P < 0.05) better at 30 C (FC = 1.36%/d; FCR = 2.6; PER = 0.88; ANER = 10.2%) than at 25 C (FC = 1.03%/d; FCR = 3.38; PER = 0.69; ANER = 6.72%), with the exception of ANPR (17.0–17.8%). Maximum growth and energy retention in juvenile mutton snapper using a diet containing 45% crude protein was obtained at dietary lipid levels of 6–9% and E: P ratios of 33.9–36.3 kJ/g protein. Studies which determine optimum protein levels and the effects of reducing E: P ratios below 33.9 kJ/g are needed to improve feed conversion and growth.     

Stocking Density and its Influence on Growth of Spotted Wolffish,Anarhichas minor,in Shallow Raceways

We compared growth properties of spotted wolffish with initial mean weight (± SE) 3.65 (± 0.15) kg reared in shallow raceways at three different densities (50, 70, and 90 kg/m², corresponding to approx. 170, 240, and 310 kg/m³) in a 447‐day‐long growth trial at ambient temperature (mean (± SD), 4.2 C ± 1.9). Growth in all three groups was comparable, but there was a trend toward higher growth at the highest density. Final mean weights (kg ± SE) were 4.90 (± 0.15), 4.80 (± 0.16), and 5.05 (± 0.11), at the 50, 70, and 90 kg/m² density, respectively. Initially, growth rates were higher at the 90 kg/m² density group compared to the two other densities, but overall growth rates were similar in all three groups. Feed conversion efficiency differed and was higher at the two highest densities compared to lowest density. The acid–base balance was influenced by the density treatment as there was a general trend toward higher partial pressure of CO₂ and HCO in the 90 kg/m² group. Calculated productivity increased almost linearly with increasing stocking density and was found to be 24, 42, and 66 g/m²/day at 50, 70, and 90 kg/m², respectively. The results show that the optimum density conditions for farming large spotted wolffish, both with respect to growth rate, feed conversion, and productivity are at densities equal to or higher than 90 kg/m².     

不同家系中华绒螯蟹幼蟹在室外和室内的生长

2015年6月上旬,将3个家系中华绒螯蟹大眼幼体分别饲养在面积为40m2(6.50m×6.15m)的稻田围隔中,每个围隔约2500尾。2015年7月中下旬,随机从中选取各3个家系的幼蟹,放入室内300L的养殖缸(30只/缸)中对比养殖。2015年8—10月连续测量了幼蟹的头胸甲宽、头胸甲长、体质量,用多重方差分析了环境、家系及生长阶段的性状参数。试验结果表明,养殖环境对A家系幼蟹生长性状的影响不显著(P0.05),对B家系则极显著(P0.01),对C家系,除了初始的生长性状影响不显著外(P0.05),其余均存在显著影响(P0.05),表明A家系具有一定的环境适应性。家系因素对幼蟹生长性状参数均存在显著影响(P0.05),表明遗传对于幼蟹的生长具有重要作用。相关分析表明,蟹种的头胸甲宽、头胸甲长在两种养殖环境中均呈极显著正相关(P0.01),相关系数分别为0.314、0.305;体质量呈不显著正相关(r=0.146,P0.05),表明以头胸甲宽、头胸甲长为选育指标得到的后代对两种养殖环境有一定的适应性。     

饲料中添加3种不同投入品对筏式浅海网箱刺参(Apostichopus japonicus)养殖生长的影响

以刺参的存活率、增重率、特定生长率和肠道蛋白酶、淀粉酶、纤维素酶及肠道组织结构变化为评价指标,通过42 d的养殖实验,研究了在基础饲料(空白组)中添加20%生物胶为粘合剂制备粘性饲料(粘性饲料对照组),通过添加浒苔干粉(浒苔组)、微生态制剂(微生态制剂组)、中草药(中草药组) 3种投入品对浅海筏式网箱养殖刺参生理及生长的影响。结果显示,在散失率方面,粘性饲料比空白组饲料散失率降低33.42%,添加浒苔干粉、微生态制剂、中草药对饲料散失率的影响差异不显著(P>0.05);在生长方面,中草药组的增重率和特定生长率均为最高,分别达到(41.50±1.39)%和(0.82±0.02)%/d,显著高于其他4个实验组;在存活率方面,微生态制剂组和中草药组的存活率显著高于空白组和粘性饲料对照组。其中,中草药组存活率最高,达到(94.03±2.28)%;在消化酶活性方面,浒苔组、微生态制剂组和中草药组的淀粉酶活性分别在第10、20、30天达到峰值,峰值分别为(1.70±0.05)、(1.60±0.04)、(1.77±0.04) U/mg prot;粘性饲料对照组的蛋白酶活性波动最大,其活性在第10天达到峰值为(1.78±0.09) U/mg prot;空白组、粘性饲料对照组和浒苔组的纤维素酶活性均呈现先升高后降低的趋势,在实验周期内中草药组的纤维素酶活性表现为持续上升,而微生态制剂组刺参的纤维素酶活性表现出先下降后上升的趋势,最低值为(0.14±0.01) μg/g·min;肠道组织结构方面,粘性饲料对照组的肠道黏膜上皮层厚度显著增加(P<0.05),浒苔组的肌肉层厚度显著增加(P<0.05),中草药组和微生态制剂组刺参肠道组织结构完整,上皮细胞分泌旺盛。研究表明,通过添加生物胶所制作的粘性饲料可显著降低饲料散失率,添加微生态制剂和中草药可显著提高网箱养殖刺参的成活率,并显著提高刺参个体的消化酶活力和增重率,添加浒苔对刺参生长影响不显著。     

Effect of Temperature on Growth and Survival in Cultured Early Juvenile Pot‐bellied Seahorses,Hippocampus abdominalis

In Tasmania, Australia, commercial seahorse culture takes place in tank systems in which approximately 75% of the water is exchanged daily from the Tamar River estuary. As such, some water conditions such as temperature fluctuate on a daily and seasonal basis. The aim of this study was to examine the effect on growth, condition, survival of, and Artemia ingestion by, early juvenile seahorses, Hippocampus abdominalis, cultured for 6 wk at temperatures within the species' natural range (8–24 C) and above it (26 C). Seahorses cultured at 20 C were longer and heavier than those at 17 C, although not significantly different to 23 C. There were no differences in survival or Artemia ingestion of juveniles cultured at 17, 20, and 23 C. At 26 C, 100% mortality was reached on Day 15. This study demonstrates that H. abdominalis can be reared in captivity at a range of 17–23 C in early life stages without compromising growth and survival.     

Effect of Dietary Phosphorus Levels on Growth, Body Composition, Muscle and Bone Mineral Concentrations for Orange-Spotted Grouper Epinephelus coioides Reared in Floating Cages

A feeding experiment was conducted in floating cages (1.5 ± 1.0 ± 2.0 m) to determine the requirement of dietary phosphorus by juvenile orange-spotted grouper Epinephelus coicodes . Five isonitrogenous (approximately 54% CP) fishmeal-casein-based diets that contained 0.68, 0.77, 0.86, 1.02 and 1.21% total phosphorus from ingredients and supplemental monocalcium phosphate (MCP: 0, 0.75,1.51,2.26,3.02%) were fed to the fish previously fed a basal diet (0.68% total phosphorus) for 2 wk. Fish were fed in triplicate cages with one of the diets twice daily to satiation. After 8 wk of feeding, survival ranged from 70.0% to 81.7% with no significant difference among dietary treatments. The relative weight gain, specific growth rate, muscle lipid, ash, calcium, iron, zinc and phosphorus, bone ash, phosphorus, iron, and zinc were significantly affected by dietary phosphorus level. There were no significant effects of increasing total dietary phosphorus on hepatosomatic index, viscerasomatic index, condition factor, muscle moisture and protein, muscle magnesium, and manganese; and bone calcium, magnesium and manganese. Based on relative weight gain, specific growth rate and bone phosphorus, a dietary level of 0.86% total phosphorus is recommended for juvenile grouper growing in floating cages.     

Effects of Diffused Aeration and Stocking Density on Growth, Feed Conversion, and Production of Florida Red Tilapia in Cages

The effects of four levels of diffused aeration (0, 6, 12, and 24 hours/day) and two stocking densities (400 and 600 fish/m³) on the culture performance of caged Florida red tilapia were evaluated in 1 m³ cages in a 2 ha watershed pond on St. Croix, U.S. Virgin Islands. Fish obtained a nutritionally-complete (36% protein), floating feed from demand feeders for 143 to 146 days. Diffused aeration had no significant ( P > 0.05) effect on fish growth, survival, feed conversion, and production in cages. Combined across all levels of diffused aeration, fish stocked at 400/cage had a greater growth rate (2.21 vs. 1.97 g/day), larger final body weight (370 vs. 335 g), and a lower feed conversion ratio (1.69 vs. 1.80) than fish stocked at 600/cage ( P < 0.05). The final biomass of fish stocked at the higher density (181 kg/m³) was greater than at the lower density (140 kg/m³). The enhancement of water exchange rates by diffused aeration did not increase tilapia growth rate or production in cages.     

The potential of pet‐grade poultry by‐product meal to replace fish meal in the diet of the juvenile spotted rose snapper Lutjanus guttatus (Steindachner, 1869)

A 12‐week feeding trial was conducted to examine the replacement of fish meal with pet‐grade poultry by‐product meal (PBM‐PG) in the spotted rose snapper Lutjanus guttatus diet. Five experimental diets were formulated to contain graded levels of PBM‐PG at proportion of 250, 500, 75 or 900 g kg^?1. The control diet contained sardine fish meal as the main protein source. Four groups of 15 randomly assigned L. guttatus juveniles were fed to satiation 3 times day^?1. Except for the fish fed the PBM‐PG90 diet, the growth performance, survival and feed utilization efficiency of the experimental fish were not significantly lower than those of the control fish. The dietary level of PBM‐PG did significantly affect the haematological characteristics (P < 0.05). The dietary dry matter and protein apparent digestibility coefficients (ADCs) decreased with increasing dietary PBM‐PG. High values for lipid ADCs were observed in all diets, with significant differences among the dietary treatments. The fish whole‐body protein, moisture, lipid and ash contents were not affected by the inclusion of dietary PBM. These results indicate that high‐quality terrestrial PBM can successfully replace more than half of the marine fish meal protein in the L. guttatus diet.     

Effect of Stocking Density on the Growth and Survival of Spotted Sand Bass Paralabrax maculatofasciatus Larvae in a Closed Recirculating System

Abstract.— The effect on growth and survival of the initial stocking density (50, 100, 150, and 200 larvae/ L) in larval rearing of spotted sand bass was evaluated over 30 d in a closed recirculating system. Larvae were fed with rotifers, copepods, nauplii and adult Artemia , and spotted sand bass yolk-sac larvae. Water quality was monitored daily. The notochordal or standard length of sampled larvae was measured by image analysis. Specific growth rates at each density were compared by covariance analysis. Survival was estimated from day 15 to the end of the experiment, when a resistance test was used to evaluate the juvenile quality among densities. At the end of the experiment, mean standard length of larvae at lower densities was significantly larger ( P < 0.05) than at higher densities. Higher specific growth rates were found at lower densities. Significantly higher survival ( P < 0.05) was recorded for the lowest density, but the highest number of harvested fish was obtained with the highest densities (150 and 200 larvae/L). The lowest density also showed the significantly ( P < 0.05) higher survival after using a resistance test. We conclude the highest density can be used in larval rearing of spotted sand bass. However, better survival, growth, and seed quality are obtained at the lowest density. To recommend an optimal density for this specie, it is necessary to improve the water quality in the culture system and to make a cost-benefit study.     

Effect of Dietary Antarctic Krill Meal on Growth Performance,Muscle Proximate Composition,and Antioxidative Capacity of Juvenile Spotted Halibut,Verasper variegatus

A 7‐wk feeding trial was conducted to evaluate the effects of dietary Antarctic krill meal (AKM) on the growth performance, proximate composition of muscles, and antioxidative capacity of juvenile spotted halibut. Six diets were formulated to contain about 50% protein and 8% lipid. A control diet (R0) without AKM and the other five diets with 8.1, 16.2, 24.3, 32.4, and 42.5% AKM supplementation (R10–50) to replace 10, 20, 30, 40, and 50% fishmeal protein were used to feed to juvenile spotted halibut. The juveniles were fed with each diet using three replicates and cultivated in the indoor culture system. Results showed that the specific growth rate, feed intake, and protein efficiency ratio in the R30 and R40 groups were significantly higher than that in other groups (P < 0.05). Survival rate in the R50 group was significantly lower compared with the R0 group and the other four AKM supplementation groups. Moreover, the rising AKM levels in diets had significant effects on the chemical composition of juvenile spotted halibut, showing significantly decreased contents of crude protein, but increased lipid and ash contents (P < 0.05). The total superoxide dismutase activity and catalase activity of serum and liver in AKM groups were significantly higher than those in the control group (P < 0.05). In contrast, the contents of malondialdehyde in serum and liver were significantly lower compared with the control group. These findings illustrate that a moderate AKM level in diets can significantly improve the growth performance, feed utilization, and antioxidative capacity in juvenile spotted halibut, which support the finding that AKM may be used as a good protein source for halibut in the aquafeed industry.