浅水塘主养淡水白鲳罗非鱼试验

对0．44hm^2的浅水塘进行了主养淡水白鲳，罗非鱼试验,共投放鱼种17522尾，重量193kg，通过驯化喂养，投喂颗粒饲料4000kg，鱼产量2824．5kg，群体增重倍数13．6     

盐碱地池塘配置网箱养鱼试验

在盐碱地一个面积为2871m^2的鱼池中，配置4个网箱．分别放养罗非鱼、淡水白鲳和鲤，箱外放养鲢、草鱼和鲤。试验结果：罗非鱼箱(20m^2)出鱼525kg．平均单产26．3kg／m^2,淡水白鲳箱(12m^2)出鱼400kg,平均单产33.3kg／m^2,鲤鱼箱两个(各12m^2)分别出鱼488．5kg和522kg，平均单产为40．7kg／m^2和43．5kg／m^2。箱外出鲢516kg,草鱼130kg，鲤1125kg。总计全池出鱼3706．5kg，亩产鱼862kg，每亩纯盈利2173．85元。试验证明：池塘配置网箱养鱼．可同池主养几种鱼，起捕容易，管理方便。     

池塘主养淡水白鲳高产技术试验

池塘主养淡水白鲳混养鲤、鲢、罗非鱼，平均每亩净产１００７．ｇｋｇ，其中淡水白鲳占６０％，每亩纯益为６１５８．４６元。试验证明：放养３１ｇ／尾的白鲳鱼种，增重倍数远大于２５０ｇ／尾的鱼种；主养淡水白鲳池塘可混养鲢、鲶、乌鳢，但不宜混养罗非鱼。     

池塘淡水白鲳、罗非鱼混养技术

本文主要论述了淡水白鲳与罗非鱼混养技术.通过在面积8亩的池塘混养淡水白鲳、罗非鱼鱼种,搭配鲢鱼、鳙鱼、湘鲫,投喂鲤鱼全价配合颗粒饲料.设置1台3kw增氧机,饲养91天,结果共生产淡水白鲳3420.75kg,罗非鱼1704 kg,湘鲫500 kg,鲢鱼、鳙鱼1725 kg.平均每亩成本4567.5元,利润1882.99元,投入产出比为1:1.412.     

淡水白鲳、罗非鱼池塘混养技术

在面积8亩的池塘混养淡水白鲳、罗非鱼鱼种,搭配鲢、鳙、湘鲫,给淡水白鲳、罗非鱼投喂鲤鱼全价配合颗粒饲料,鲢、鳙、湘鲫不投饵。设置1台3kW增氧机,饲养91d,共生产淡水白鲳3420.75kg、罗非鱼1704kg、湘鲫500kg、鲢、鳙1725kg。每亩产量918.7kg,每亩成本4567.5元,每亩利润1882.99元,投入产出比为1∶1.412。     

池塘养淡水白鲳高产技术试验

池塘主养淡水白鲳混养鲤、鲢、罗非鱼，平均每亩净产１００７．９ｋｇ，其中淡水白鲳占６０％，第亩纯益为６１５８．４６元。试验证明：放养３１ｇ／尾的白鲳鱼种，增重倍数远大于２５０ｇ／尾的鱼种；主养淡水白鲳池塘可混养鲢、鲶、乌鳢，但不宜混养非鱼。     

池塘主养淡水白鲳高产技术

1995-1996年，我们利用配合饲料在0．73公顷池塘中主养淡水白鲳，经过140天养殖，平均每公顷净产鱼10792．2kg，其中淡水白鲳8287．2kg，平均体重为454．1克／尾；每公顷盈利105520．1元，投入产出比为1：2．05。     

淡水白鲳与奥尼罗非鱼池塘健康混养试验

2007年，松溪县水技站在岩洞鱼场0．4hm2的池塘，进行了淡水白鲳与奥尼罗非鱼混养试验，取得了不错的养殖效果。1材料与方法1．1鱼类介绍1．1．1淡水白鲳生活习性淡水白鲳栖息在中、下水层，具集群性，能耐0．48mg／L低氧；最适pH值6．2～7．5。16℃开始正常吃食，生长温度为21％～32％，最适生长温度为28℃～30℃。淡水白鲳不耐低温，夏花鱼种饲养水温必须保证17℃以上，水温12℃时，大部分成鱼失去平衡，低于8℃死亡。为杂食性鱼类，以蚕食方式摄食。仔鱼阶段摄食浮游生物为主，幼鱼也食有机碎屑和人工饲料。     

北方冬季利用温泉水养殖罗非鱼苗种高产模式

2009年2—6月,在辽宁省兴城市温水养殖场利用温泉水培育罗非鱼苗种高产模式试验。试验期间共培育出罗非鱼苗种4．5万kg,平均体重93．7g／尾,平均单产68116．5kg／hm^2。现将试验情况报告如下：     

淡水白鲳养殖技术

淡水白鲳，学名为短盖巨脂鲤，隶属脂鲤目，脂鲤科，巨脂鲤属。原产于南美洲亚马逊河，为热带鱼类，正常生长温度为21～32℃．最适温度为25～30℃。此鱼与罗非鱼一样不能在自然水温条件下越冬。2003年5月中旬．我县从湘南引进8cm左右的鲳鱼苗3000尾，在同欢水库渔场的0．33hm^2鱼池试养，养殖3个月，尾重达到0．5kg以上，最大个体0．75kg，被钓、购一空，市场前景较好。     

Comparison of stocking time and density on Gulf Killifish growth in freshwater ponds

The Gulf Killifish (Fundulus grandis) is a popular baitfish and a candidate for commercial‐scale production. For inland production, ponds may need to be stocked at different times and densities to meet market demands. Therefore, in Experiment 1, juveniles were stocked into freshwater ponds at a density of 25,000 fish/ha, with two cohorts (mean total length (TL) = 3.92; 3.52 cm) stocked 1 month apart and evaluated for 12 weeks. Cohort 1 had a lower overall survival (40%) than cohort 2 (79%); with no difference between mean final TL (8.46; 8.00 cm); reaching a market size of 6 cm in 22 days and 32 days respectively. In Experiment 2, juveniles (mean TL = 3.16; 3.23 cm) were stocked into freshwater ponds at two densities (25,000 fish/ha and 50,000 fish/ha). Mean final TL was greater in the lower stocking density (8.68 cm) than the higher stocking density (8.20 cm); with no differences in survival between treatments (75; 72%) respectively. Lower stocking and higher stocking densities reached a market size of 6 cm in 29 and 31 days respectively. These results suggest that multiple cohorts can be stocked and grown to market size in one season at a stocking density of 50,000 fish/ha.     

ENERGY CONVERSION EFFICIENCY IN THREE ECOLOGICAL TYPES OF POND IN THE PEARL RIVER DELTA IN CHINA

本文研究了珠江三角洲三种不同生态类型池塘的能量转换效率。三种不同类型的池塘分别是：１）静水塘，面积０．２４７ｈａ，试验期间不换水，也没有其它增氧设施；２）加水塘，面积０．１９３ｈａ，每天加水２，７００－３，０００Ｍ３／ｈａ；３）微流水塘，面积０．１９３ｈａ，每天由潮汐自然进水３０，２５５－４２，４８０Ｍ３／ｈａ。另外，加水塘和微流水塘各配一台３千瓦的叶轮式增氧机，在鱼浮头时使用。结果表明增加池塘的换水量可以增加鱼产量，提高池塘的能量转换效率。还表明换水量大的池塘其生物能占的比例较大，而光合能占的比例则较小。为提高池塘的能量转换效率和鱼产量，必须增加“直食性”鱼类的放养量、减少“滤食性”鱼类的放养量。     

Growth, Survival, Yield, and Size Distributions of Freshwater Prawn Macrobrachium rosenbergii and Tilapia Oreochromis niloticus in Polyculture and Monoculture Systems in Puerto Rico

Abstract.— Tilapia and freshwater prawn production in Puerto Rico for monoculture and polyculture systems were compared. The experiment consisted of three treatments with three replicates each. The stocking rates for the prawn monoculture, fish monoculture and polyculture treatments were respectively: 7 prawns/m², 1 tilapia/M², and 7 prawns with 1 tilapia/ m². The mean stocking size for tilapia and prawn were respectively, 7–8 g and 1–1.3 g. After 145 d of culture, yields and mean weight of tilapia in monoculture and polyculture system were not significantly different. Total yields were 2,942 and 2,769 kg/ha, respectively. Mean weights were 348 g in monoculture and 331 g in polyculture. Yields and mean weight of prawns in monoculture and polyculture were significantly different. Total yields were 1,367 and 951 kg/ha, respectively. Mean weights were 55 g in monoculture and 31 g in polyculture. Total yield in polyculture was 3,720 kg/ha showing an increase over the production separately obtained in prawn and fish monoculture.     

Effect of salinity on the rearing performance of juvenile golden pompano Trachinotus ovatus (Linnaeus 1758)

Effect of rearing salinity on the performance of juvenile golden pompano Trachinotus ovatus (Linnaeus 1758) was studied under a laboratory condition. Fish growth, survival, RNA/DNA ratio, pepsin activity, α‐amylase activity and FCR were used as evaluation criteria. The growth and RNA/DNA ratio were significantly affected by the rearing salinity. High growth rate and RNA/DNA ratio were observed when fish were reared at the salinity of 34‰. The pepsin activity of fish was not significantly affected by the rearing salinity. However, the α‐amylase activity of fish was significantly affected by the rearing salinity. The α‐amylase activity of fish reared at the salinity of 10‰ was significantly lower than fish cultured at the salinity of 34‰. Rearing salinity can significantly affect the FCR of juvenile golden pompano. The FCR of fish cultured at the salinity of 10‰ was 5‐times higher than the FCR of fish reared at 34‰. Results from the present study indicate that juvenile golden pompano can be reared above 26‰ without affecting fish performance, and the salinity of 10‰ may be too low to rear juvenile golden pompano as fish growth, RNA/DNA ratio and α‐amylase activity were reduced.     

The culture, zooplankton dynamics and predator-prey interactions of Chesapeake Bay striped bass, Morone saxatilis (Walbaum), in estuarine ponds

Abstract. Four 0.05-ha research ponds were filled with brackish water (12 ppt) for the purpose of evaluating zooplankion dynamics and predator-prey interactions. Three of the ponds were stocked with Chesapeake striped bass, Morone saxatilis (Walbaum). All ponds were fertilized to stimulate zooplankton blooms using a protocol that has been successful in freshwater systems. Zooplankton was dominated by four major groups: rotifers, copepod nauplii, Eurytemora adults and Eurytemora copepedites with rotifers and the nauplii being the most abundant organisms found. Rotifer populations peaked 15-20 days after filling while the copepods peaked 17-22 days after filling. Fish production was very similar to that found in freshwater ponds with an average yield of 84.4 kg/ha (2.0 kg/ha/day) for phase 1 fish (=45mm). Food selectivity indices indicated striped bass avoided both rotifers and copepod nauplii and preferred adult and copepedite Eurytemora as a food item. However, due to various problems associated with sampling, these selectivity results should be considered with caution. The findings of this study reveal fertilization regimes used successfully in freshwater production systems can be applied in an estuarine environment.     

The Effect of Varying Biomass of Carryover Fish in Multiple‐batch Catfish,Ictalurus punctatus,Pond Production

The presence of carryover (fish >350 g stocked the previous year but not yet market size) channel catfish, Ictalurus punctatus, in multiple‐batch production ponds has been shown to affect overall production performance and costs. However, little attention has been paid to effects of varying biomasses of carryover fish in ponds. Twelve 0.1‐ha earthen ponds were stocked March 20, 2007, with 15,000 catfish fingerlings per ha (mean weight 31 g), and carryover fish at either 726, 1460, or 2187 kg/ha (mean weight 408 g, range 204–703 g) to compare the effect of three different biomasses of carryover catfish on the production performance of understocked fingerlings. Gross and net yields increased with increasing biomass of carryover fish. Growth and mean weight at harvest of fingerlings were significantly greater at the lowest biomass of carryover fish (<1460 kg/ha), but there was no difference between the medium and high carryover density treatments. Net returns were highest with the highest biomass of carryover fish, but fell by $688/ha in Year 2 because of slower growth of fingerlings in Year 1.     

Beef tallow is suitable as a primary lipid source in juvenile Florida pompano feeds

It is assumed that Florida pompano have dietary EPA (20:5n‐3) and DHA (22:6n‐3) requirements. However, it is unclear whether both are equally important in meeting demand for n‐3 long‐chain polyunsaturated fatty acids (LC‐PUFAs) or whether the requirement(s) can be influenced by other fatty acids. Accordingly, we assessed production performance and tissue composition of juvenile Florida pompano (41.0 ± 0.5 g) fed diets containing fish oil; beef tallow; or beef tallow partially or fully supplemented with EPA, DHA or both. After 8 weeks, no signs of fatty acid deficiency were observed. Although fish performance did not vary significantly among the dietary treatments, fish fed the DHA‐supplemented feeds exhibited numerically superior growth than those fed the other diets. Fillets of fish fed the beef tallow‐based diets contained reduced levels of n‐3 fatty acids and LC‐PUFAs and elevated levels of MUFAs and n‐6 fatty acids, although dietary supplementation with EPA and/or DHA attenuated these effects somewhat. Our results suggest that beef tallow is suitable as a primary lipid source in Florida pompano feeds and n‐3 LC‐PUFA requirements may be met by as little as 4 g/kg EPA and 4 g/kg DHA. However, there may be value in supplementing tallow‐based diets with DHA to enhance tissue levels and possibly growth.     

Effect of weaning time on the performance of Trachinotus ovatus (Linnaeus 1758) larvae

Effect of weaning time on the larval performance of golden pompano Trachinotus ovatus was studied in the experimental condition. The same weaning regime started on four different days of posthatch (DPH): 13 DPH (W13), 16 DPH (W16), 19 DPH (W19) and 22 DPH (W22), respectively. Growth, survival, RNA/DNA ratios and mid‐gut cell height of fish were assessed in each weaning regime over time. Growth and survival rates of fish larvae weaned in the W19 and W22 regimes were significantly higher than those in the W13 and W16 regimes. No significant differences were found either between W19 and W22, or between W13 and W16 treatments. Fish showed a decrease in the RNA/DNA ratio in W13, but a trend of increase in W16, W19 and W22. Weaning time significantly affected the mid‐gut cell height in larval golden pompano. On 24 DPH, the mid‐gut cell height of fish in the W13 and W16 treatments was significantly thinner than those in the W19 and W22 treatments. Based on fish growth, survival, RNA/DNA ratio and mid‐gut cell height, weaning can be started on 13 DPH in golden pompano larvae, but we recommend that the best weaning window be 16–22 DPH. These results are supported by histological and nutritional evidence and would guide the weaning process for golden pompano larvae, and offer a useful approach to explore the weaning protocol in larval fish rearing.     

Growth, Survival, and Body Composition of Cage-Cultured Nile Tilapia Oreochromis niloticus Fed Pelleted and Unpelleted Distillers Grains with Solubles in Polyculture with Freshwater Prawn Macrobrachium rosenbergii

Abstract.— A 12‐wk feeding trial was conducted in cages with juvenile Nile tilapia Oreochromis niloticus to evaluate distillers grains with solubles (DDGS) as a direct feed, the effects of pelleting on its utilization, and the compatibility of caged tilapia and prawns in polyculture. Nine 1.0‐m³ cages were stocked with 200 juvenile (26 ± 0.9 g) tilapia. Cages were suspended in a 0.2‐ha pond stocked with juvenile freshwater prawns Macrobrachium rosenbergii at 40,000/ha. Three replicate cages were randomly assigned to each dietary treatment. In one dietary treatment DDGS was fed as an unpelleted loose grain ration (26% protein). In a second dietary treatment fish were fed DDGS that had been steam‐pelleted (23% protein). Fish in a third dietary treatment were fed a commercial catfish diet (31% protein) for comparison. After 12 wk, individual weight, individual length, and specific growth rate were significantly higher (P < 0.05) and feed conversion ratio was significantly lower (P < 0.05) for fish fed the commercial catfish diet than for fish fed either unpelleted or pelleted DDGS. Specific growth rate was significantly higher (P < 0.05) for fish fed pelleted DDGS than for fish fed unpelleted DDGS. Survival did not differ significantly (P > 0.05) among treatments (>95%). Although growth was increased in fish fed the commercial diet, their cost of production (<0.66/kg gain) was significantly higher (P < 0.05) than in fish fed unpelleted and pelleted DDGS (<0.26/ kg gain and <0.37/kg gain, respectively). The costs of gain in fish fed unpelleted DDGS was significantly lower (P < 0.05) than in fish fed the pelleted DDGS. Prawn production was 1,449 kg/ha and addition of tilapia in polyculture increased total pond productivity approximately 81 %. These data suggest that DDGS provides economical growth in tilapia when fed as a direct feed and that polyculture of tilapia may improve overall pond efficiency in freshwater prawn production ponds, even at temperate latitudes.     

Evaluation of a Low‐head Recirculating Aquaculture System Used for Rearing Florida Pompano to Market Size

A low‐head recirculating aquaculture system (RAS) for the production of Florida pompano, Trachinotus carolinus, from juvenile to market size was evaluated. The 32.4‐m³ RAS consisted of three dual‐drain, 3‐m diameter culture tanks of 7.8‐m³ volume each, two 0.71‐m³ moving bed bioreactors filled with media (67% fill with K1 Kaldness media) for biofiltration, two degassing towers for CO₂ removal and aeration, a drum filter with a 40‐µm screen for solids removal, and a 1‐hp low‐head propeller pump for water circulation. Supplemental oxygenation was provided in each tank by ultrafine ceramic diffusers and system salinity was maintained at 7.0 g/L. Juvenile pompano (0.043 kg mean weight) were stocked into each of the three tanks at an initial density of 1.7 kg/m³ (300 fish/tank). After 306 d of culture, the mean weight of the fish harvested from each tank ranged from 0.589 to 0.655 kg with survival ranging from 57.7 to 81.7%. During the culture period, the average water use per kilogram of fish was 3.26 or 1.82 m³ per fish harvested. Energy consumption per kilogram of fish was 47.2 or 22.4 kwh per fish harvested. The mean volumetric total ammonia nitrogen (TAN) removal rate of the bioreactors was 127.6 ± 58.3 g TAN removed/m³ media‐d with an average of 33.0% removal per pass. Results of this evaluation suggest that system modifications are warranted to enhance production to commercial levels (>60 kg/m³).