Yellow croaker (Pseudosciaena crocea) growth in cages was evaluated from fingerling to sub-market size with extruded pellet and fresh fish rations in ASA feeding trials at Xiangshan, Ningbo and Nanji Island, Wenzhou. The extruded feed was a soymeal-based ration containing 43% crude protein and 12% fat and was fed in extruded, floating pellet form. Fresh fish was fed in chopped form. Yellow croaker fingerlings were stocked in 8.0-m3 cages at 200 fish per m3 in the Ningbo trial and 175 fish per m3 in the Wenzhou trial. In the Ningbo trial, yellow croaker grew from 3.2 g to 37.9 g in 103 days on the extruded feed, with an FRC of 1.69:1, and from 3.4 g to 44.0 g in 103 days on the fresh fish ration, with an FCR of 9.92:1. Net income and ROI were 27% and 82% higher, respectively, for fish fed the extruded feed than for fish fed the fresh fish ration in the Ningbo trial. In the Wenzhou trial, yellow croaker grew from 5.4 g to 23.4 g in 62 days on the extruded feed, with an FCR of 1.53:1, and from 5.6 g to 25.4 g in 62 days on the fresh fish ration, with an FCR of 4.98:1. Net income and ROI in the Wenzhou trial were nearly identical for the two feed treatments, but any increase in the cost of fresh fish above the RMB 1.0/kg rate that prevailed during the trial would favor the use of the extruded feed. Results of both trials demonstrated good growth performance, feed conversion and economic return with the soymeal-based extruded feed and ASA cage technology. The added benefits of quality consistency, less nutrient loading of the aquatic environment, ease in shipping and storing, and absence of potential pathogens make manufactured feed a better choice than fresh fish for feeding yellow croaker.

Red drum growth from advanced fry to 3-g fingerlings was compared using wild caught fresh fish and manufactured feed rations. Wild caught fresh fish was fed in a ground, paste form. Manufactured feeds were fed as No. 3 (1.1-1.5 mm) crumbles and 1.5-mm extruded pellets. Red drum fry were stocked in 2.25-m3 cages at a density of 2,500 fish per cage at 36 days post swim-up. Red drum fry grew from an average weight of 0.21 g to 3.24 g and 3.42 g, respectively, on the manufactured feeds and fresh fish paste in 24 days. Feed conversion ratios for the manufactured feeds and fresh fish paste were 1.43:1 and 5.17:1, respectively. Fish survival was 91.5% for fish fed the manufactured feeds, and 81.0% for fish fed the fresh fish paste. While growth was 5% better with the fresh fish paste, higher fish survival and better feed conversion with the manufactured feeds resulted in higher fish production and greater economic return. Results indicate that manufactured feeds can effectively replace fresh fish as the starter food for advanced red drum fry in cages.

The American Soybean Association (ASA), in cooperation with the China National Fisheries Extension Center (NEC) and the Guangxi Provincial Fisheries Extension Station, conducted cage feeding trials with red drum (Sciaenops ocellata), Japanese sea bass (Lateolabrax japonicus), and blackfin sea bream (Acanthopagrus sp.) at Longmen Town, Qingzhou City, Beihai in 2000. The objective of the trials was to demonstrate that sub-market size fish of each of the three test species could be weaned from a fresh fish diet to a soymeal-based, extruded feed and economically grown to market size on the extruded feed.

The American Soybean Association (ASA), in cooperation with the China National Fisheries Extension Center (NEC), the Guangdong Provincial Fisheries Extension Center, and the Long Gang Fisheries Research Institute coastal cage culture farm in Dong Shan Bay, conducted feeding trials with green grouper (Epinephelus awoara), red drum (Sciaenops ocellata) and pompano (Trachinotus ovatus) in 2000. The objective of the green grouper and pompano trials was to compare growth and economic performance of these species from fingerling to market size with a traditional fresh fish diet and a soymeal-based, extruded aquafeed. The objective of the red drum trial was to demonstrate that sub-market size red drum could be weaned from fresh fish to a soymeal-based manufactured feed and economically grown to market size on the manufactured feed.

A feeding trial was conducted at the Tai Xing Fish Stock Farm in Tai Xing, Jiangsu Province, to demonstrate the fry to fingerling growth performance of wuchang bream using the ASA 80:20 production model and ASA soymeal-based fry and fingerling feeds. Fish were stocked in three, 2.0- mu ponds at densities of 5,000 wuchang bream and 800 silver carp fry per mu. Wuchang bream grew from 0.2 g to an average weight of 43.8 g per fish in 117 days of feeding. Gross production averaged 189.1 kg/mu for wuchang bream and 60.5 kg/mu for silver carp. Average survival rates for wuchang bream and silver carp were 86.4% and 96.4%, respectively. Wuchang bream FCR for the combination of ASA fry and fingerling feeds was 1.36:1. Net economic return for the three trial ponds averaged RMB 392.61/mu per mu. ROI averaged 18%. Results of the feeding demonstration showed that wuchang bream fed well on extruded, floating feed, and exhibited good growth performance, FCR, survival and economic return with the ASA soymeal-based feeds and 80:20 production technology.

Yellow croaker growth from the advanced fry to fingerling stages was compared using fresh fish and manufactured feed rations. Fresh fish was fed in a ground, paste form. A manufactured starter feed was fed in No. 2 crumble form. Croaker fry were cultured in 2.25-m3 cages at a density of 2,500 fish per cage. Yellow croaker fry grew from an average weight of 0.67 g to 3.4 g and 3.2 g, respectively, on the fresh fish paste and manufactured feed in 45 days. Croaker had difficulty ingesting the crumble feed because of the small particle size. Observations suggest an optimal feeding regime of two weeks on crumble feeds, followed by extruded pellets beginning at fish size 0.7 g.

Channel catfish (Ictalurus punctatus) growth in 1-m3 cages was evaluated with three extruded feed rations with varying soybean meal and fishmeal inclusion rates. One ration was formulated as an all- plant protein diet with dehulled soybean meal as the primary protein source. The second ration was formulated with dehulled soybean meal as the primary protein source, but with 5% fishmeal. The third ration was formulated with fishmeal as the primary protein source. All three rations were designed to be nutritionally the same, with 32% protein and 6% fat. Channel catfish stocked at 400 fish per m3 grew from 69g to 467 g, 500 g and 532 g, respectively, on the all-plant protein soy-based, soy-based with 5% fishmeal, and fishmeal-based rations. Growth was significantly different (P<0.05) among the three rations. FCR for the soy-based, soy-based with 5% fishmeal, and fishmeal-based rations was 1.45:1, 1.34:1 and 1.25:1, respectively. Net production for the soy-based, soy-based with 5% fishmeal, and fishmeal-based rations averaged 157 kg/m3, 171 kg/m3 and 183kg/m3, respectively. Survival averaged 99% for all feed treatments. Net economic return at the prevailing market price of RMB 21/kg was RMB 2147/m3, RMB 2373/m3 and RMB 2570/m3, respectively, for the all-plant protein soy-based, soy-based with 5% fishmeal, and fishmeal-based feed rations. Return to investment averaged 124%, 134% and 139% for the soy-based, soy-based with 5% fishmeal, and fishmeal-based ration treatments, respectively. Net economic return and return to investment were significantly different (P<0.05) among the three feed treatments.

Three fingerling sizes of crucian carp were grown to market size in ponds using the ASA 80:20 production model and a soy-based diet. Fish were Fengzhen crucian x Xingguo red common carp bred in 1998 at the Tai Xing Fish Stock Farm in Jiangsu Province. Fish were stocked at 1000 crucian carp per mu together with 60 silver carp per mu. Fingerlings of sizes 63 g and 44 g grew respectively to 411 g and 383 g in 212 days of feeding. Fingerlings of size 32 g grew to 363 g in 214 days of feeding. The 63-g fingerlings reached a market size of 250 g in 150 days, while the 44-g and 32-g fish reached 250 g in 158 and 165 days, respectively. Stocking fingerlings of different sizes may be a good management strategy for fish farmers interested in extending the marketing season for crucian carp. Feeding for 212 to and 214 days yielded 363-g to 411-g fish having high market value because of their large size. FCR with the ASA all-plant protein, soy-based diet averaged 1.50 to 1.61. Use of this diet in the extruded, floating form allowed the Tai Xing farm manager to closely monitor fish feeding performance and fish health and prevented over-feeding of fish and wasting of feed.

Feed particle size requirements for crucian carp of 2-cm to 7-cm total length were determined in a joint study by ASA and the Zhejiang Freshwater Fisheries Research Institute in Huzhou, China. Results were used to formulate feed size recommendations for fish farmers producing crucian carp using feed-based production technologies. Crumble feeds of size 0.5-mm and 1.0-mm are recommended for fry of 2-cm and 3-cm total length, respectively. Crucian carp fry can be weaned to a 1.5-mm extruded pellet at 5-cm total length.

Grass carp were grown from fry to fingerlings on two feed regimes using the ASA 80:20 production model and soy-based feeds. Grass carp grew from 0.3 g to 83 g when fed a 36% protein, soy-based diet for the entire production season. Grass carp grew from 0.3 g to 78 g when fed a 36% protein, soy-based diet to size 25 g, followed by feeding with a 32% protein, soy-based diet thereafter. Growth was significantly different with the two feed regimes. FCR for the 36% protein feed regime was 1.12:1 for the 121-day feeding period. FCR for the combination feed regime was 1.19:1. No economic benefit was obtained by reducing the protein content of the feed once grass carp reached 25g in weight. The reduction in feed cost obtained with the combination feed regime was offset by the better growth performance of fish receiving the 36% protein feed for the duration of the production season.

Two fingerling sizes of grass carp were grown to market size in ponds using the ASA 80:20 production model and a soy-based diet. Fish were stocked at 600 grass carp per mu together with 100 silver carp per mu. Fingerlings of sizes 70 g and 100 g grew respectively to 797 g and 827 g in 178 days of feeding. Net production for the three, 100-g fingerling ponds averaged 438 kg/mu of grass carp and 113 kg/mu of silver carp. Net production for the three, 70-g fingerling ponds averaged 429 kg/mu of grass carp and 108 kg/mu of silver carp. The 100-g fingerlings reached a target market size of 750 g in 156 days, while the 70-g fingerlings reached 750 g in 165 days. FCR with the ASA all- plant protein, soy-based diet was 1.22 for the 70-g fingerlings and 1.19 for the 100-g fingerlings. Use of this diet in the extruded, floating form allowed the Xu Xing Zhang farm manager to closely monitor fish feeding performance and fish health and prevented over-feeding of fish and wasting of feed. Net economic return and return on investment were RMB 804/mu and 24% for the 70-g fingerling treatment, and RMB 449/mu and 11.7% for the 100-g fingerling treatment.

Japanese Sea Bass (Lateolabrax japonicus) growth in cages was evaluated with two ioscaloric and isonitrogenous feed rations formulated to contain 43% protein and 12% fat. One ration was formulated predominantly with fishmeal, while the other ration contained 40% dehulled soybean meal. Fish were stocked in 8.0-m3 cages at 350 fish per m3 and fed for 153 days. Sea bass grew from 3 g to 297g with the soy-based ration, and from 3 g to 289 g with the fishmeal-based ration. There was no significant difference in fish growth (P>0.05) with the two feeds. FCR averaged 1.53:1 and 1.55:1 for the soy-based and fishmeal-based rations, respectively. Survival averaged 50% for all cages and treatments. This was the first phase of a two-phase trial. Fish will be grown to a >500 g market size during the year 2000 phase two component of the trial.

Pompano (Trachinotus ovatus) growth in cages was evaluated with fishmeal and soybean meal based feed rations. Two ioscaloric and isonitrogenous feed rations were formulated to contain 43% protein and 12% fat. One ration was formulated predominantly with fishmeal, while the other ration contained 40% dehulled soybean meal. Fish were stocked in 1.5-m3 cages at 400 fish per m3 and fed for 150 days. Pompano grew from 2.7 g to 222 g with the soy-based ration, and from 2.7 g to 218 g with the fishmeal-based ration. There was no significant difference in fish growth (P>0.05) with the two feeds. FCR averaged 2.13:1 and 2.23:1 for the soy-based and fishmeal-based rations, respectively. Survival averaged 72% for all cages and treatments. Net economic return was 12% higher and return to investment was 10% greater with the soy-based ration. Production of pompano in cages with manufactured feeds was demonstrated to be both technically and economically feasible. Replacement of fishmeal with dehulled, high protein soybean meal resulted in no reduction in fish growth and a significant cost savings for feed.

A feeding demonstration was conducted in Harbin in 1999 to demonstrate the advantages of ASA’s 80:20 pond technology and soy-based diets for producing bigmouth buffalo fingerlings. Bigmouth buffalo fry with an average weight of 0.5 g were stocked in two 7-mu ponds in Harbin in May and fed soy-based feeds for 106 days between June and September. The fry grew from 0.5 g to 60 g during this period, with an average FCR of 0.93:1. Net production averaged 244 kg/mu of bigmouth buffalo fingerlings and 62 kg/mu of silver carp fingerlings. Average survival for bigmouth buffalo was 83%. Net economic return was RMB 4,108/mu, with a 114% return to investment. The trial successfully demonstrated the value of the 80:20 technology and both the production and economic advantages of soy-based aquafeeds.

Hybrid wuchang bream (Megalobrama hoffmanni) were grown to market size in ponds using the ASA 80:20 production model and an extruded, soy-based feed. Hybrid wuchang bream grew from 64g to 508 g in 184 days at a stocking density of 800 fish per mu. Net production in three, approximately 5-mu ponds averaged 293 kg/mu of wuchang bream and 71 kg/mu of silver carp. FCR with the ASA soy-based feed was 1.97:1. Net economic return was RMB 634/mu, with a 16.1% return to investment.

A 10-day feeding demonstration was conducted at Rao Ping, Guangdong Province, to determine if coastal aquaculture species could be weaned from a fresh fish diet to extruded, manufactured feeds. Sea bass weighing 55 g and 110 g, red drum weighing 150 g, and juvenile snapper sea bream 5-6 cm in length were tested in the demonstration. All species and all sizes of fish were successfully weaned to extruded feed pellets. Sea bass readily consumed extruded pellets on the second day of the weaning process. Snapper sea bream of size 5-6 cm consumed extruded pellets on the first day pellets were presented. Red drum was the most difficult of the species tested to wean to extruded pellets.

The American Soybean Association (ASA), in cooperation with the China National Fisheries Extension Center (NEC) and its affiliate provincial agencies, has conducted a series of feeding trials with tilapia in ponds and cages over the past five years. These trials have been conducted on commercial fish farms throughout China, and have tested a variety of feeds and feed formula variations to determine the technical and economic feasibility of culturing tilapia in feed-based pond (80:20 technology) and cage (LVHD technology) production systems with soybean-based aquafeeds. These efforts were continued in 1997 with a feeding trial in Guangzhou that evaluated hybrid tilapia growth performance from fry to market size on soybean-based fingerling and grow-out diets.

The American Soybean Association (ASA), in cooperation with the China National Fisheries Extension Center (NEC) and its affiliate provincial agencies, has conducted a series of production trials with native and imported fish species since 1991 to demonstrate and evaluate the technical and economic feasibility of feed-based fish culture in China. Tilapia have been one of the key imported species evaluated for both pond and cage production in China. ASA continued its evaluation of tilapia in 1997 with a feeding trial that examined the production performance of red tilapia in LVHD cages with soybean meal-based feeds.

Fourteen pond trials were conducted in 1995 and 1996 to assess the fingerling to market growth of crucian carp, pacu, tilapia and wuchang carp (bream) with a variety of aquafeed formulations. The objective of the trials was to test and demonstrate the technical and economic feasibility of production of these species in 80:20 culture systems with feeds formulated primarily from plant proteins. An all-plant protein diet (‘J’) was tested against similar diets (‘H’ and ‘K’) containing primarily plant protein and 5% fish meal.

The all-plant protein ‘J’ diet produced as good or better growth than the ‘H’ diet containing fish meal with crucian carp. Crucian carp of approximately 50 g grew to an average of 227 g in six trials. The production target of 250 g was reached in only two trials. Float and sink forms of the test diets produced inconsistent results. Observations indicate crucian carp are not aggressive feeders and may require training at the fry to fingerling stage to readily adapt to floating feeds. Economic return with crucian carp was highly variable.

Pacu reached the production target of >400 g in two trials conducted and with all three diets tested (‘H’, ‘J’ and ‘K’). There was no difference in pacu growth among the test diets, or among floating and sinking forms of the ‘H’ diet. Feed conversion ratios of 1.2-1.6 indicated rapid and economical growth of pacu on all diets.

Nile tilapia growth was best on the ‘K’ diet, although tilapia grew rapidly on both the ‘J’ and ‘K’ diets tested in one trial in 1995. Average daily growth rates were 8.3% and 9.7% of body weight, respectively, with 31-g fingerlings growing to 355-410 g in 126 days. A 1996 trial stocked fingerlings of 6 g that were unable to attain market size by the end of the production season. There was no growth difference of fingerlings with the ‘J’ and ‘H’ feeds.

Bream growth was also better on the ‘K’ diet, with only minor variations in growth among the ‘H’ and ‘J’ diets in three trials. Floating feeds produced better growth than sinking feeds with bream. Average bream growth, feed conversion ratio and economic return with the three diets was 356 g, 1.8 and Y3255/mu.

Twenty-three cage trials were conducted in 1995 and 1996 to assess fry-fingerling and fingerling-market production potential of Nile tilapia, common carp, crucian carp, wuchang carp (bream), and channel catfish in low-volume high-density (LVHD) cages. The objective of the trials was to test and demonstrate the technical and economic feasibility of production of these species in LVHD cage culture systems with feeds formulated primarily from plant proteins. An all-plant protein diet was tested against similar diets containing 5-10% fish meal.

The all-plant protein ‘J’ diet produced as good or better growth than the ‘H’ and ‘K’ diets containing 5% fish meal in 6 of 8 comparison trials with nile tilapia, 5 of 7 trials with common carp, and all trials with crucian carp and bream. Nile tilapia averaged daily weight gains of 5.4% and 3.1% per day for 50 g and >96 g fingerlings, respectively. Average net income was Y335/m3 ($40.55/m3) for all Nile tilapia trials reporting economic data. Highest net income was Y562/m3 ($68.04/m3) with the ‘J’ floating feed. Nile tilapia fry to fingerling production inLVHD cages was technically and economically feasible, with average net economic returns of Y360/m3 ($43.58/m3).

Common carp did not demonstrate a requirement for fishmeal in formulated feeds. Fish in seven cage trials gained an average of 2.6% of body weight per day on all diets tested. Best comparative growth performance was with the ‘H’ and ‘J’ feeds. The ‘H’ feed produced 7-13% better growth than the ‘K’ feed in two comparison trials. There were no differences in growthwith the ‘K’ and ‘S’ feeds in one comparative trial. Stocking density had no effect on common carp growth. Fish at 400-500/m3 grew at an average rate of 2.65% of body weight per day, while fish at 270-300/m3 grew at an average rate of 2.5% of body weight per day.

Crucian carp fingerlings of 20-26 g did not attain a target market size of 250 g in two cage production trials. Maximum growth with 26-g fingerlings was 177 g with the ‘J’ feed. Stocking of larger fingerlings is indicated to reach market size by the end of the production season. Average FCR of 2.45 was high and indicates a need to modify feed formulations for crucian carp in cages.

Bream did not demonstrate a requirement for fishmeal in one LVHD trial conducted. Floating forms of the ‘H’ and ‘J’ feeds produced 6.7% better growth than the sinking forms of the feedsat the 330/m3 density tested. Fingerling stocking size of 35 g was too small to produce market size fish in this trial.