The Effects of Live and Artificial Diets on Feeding Performance of Cultured Winter Flounder,Pseudopleuronectes americanus,in the Wild: Survival,Feeding, Growth,and Nucleic Acid Analyses

This research, which is part of a larger study designed to assess the feasibility of winter flounder, Pseudopleuronectes americanus, stock enhancement in New Hampshire, identifies hatchery feeds that optimize feeding‐related performance of fish once released in the wild. Fish reared on post‐nauplii of brine shrimp, Artemia sp., white worms, Enchytraeus albidus, common burrower amphipods, Leptocheirus plumulosus, and formulated pellets were evaluated post‐release from in situ cages using survival, growth rate, feeding onset and incidence, stomach fullness, diet composition, and nucleic acid‐based condition as indicators of hatchery diet suitability. Amphipod‐reared fish had the highest mean stomach content index of all feed types, including wild fish. Wild and worm‐reared fish exhibited the most similar survival, overall stomach fullness, and diet composition profiles over time. Amphipod‐reared fish ranked highest in overall performance; however, if wild fish performance is viewed as the ideal for a stocked fish, worm‐reared fish performed optimally. This study describes hatchery feeding strategies that may ease the transition of flatfish released into the wild for stock enhancement.     

青蛤池塘冬季暂养技术

利用冬季闲置的虾池,将滩涂上养殖的青蛤集中到池内进行暂养,由于冬季水温较低,青蛤代谢作用缓慢,可实现高密度养殖。在春节前后青蛤售价较高时,破冰捞取青蛤,可获得较高的利润。     

Pond Production of Fingerling Walleye,Stizostedion vitreum,in the Northern Great Plains

The cultural practices used to produce fingerling walleye, Stizostedion vitreum, in drainable earthen ponds are described for a state fish hatchery in Nebraska and two federal hatcheries in North Dakota. The ponds were filled 1 to 7 days before D2-D4 (Dl=the day of hatch) walleye fry were stocked. At one hatchery, ponds were sometimes double-cropped, first for production of northern pike, Esoxlucius. The two federal hatcheries fertilized ponds with ground alfalfa hay or pellets, while the standard practice at the Nebraska hatchery was not to fertilize walleye ponds, because of concern that fertilization would result in weed problems and oxygen depletion. One hatchery seeded the ponds with rye grass in the fall. Two of the hatcheries regularly used herbicides to prevent the stranding of fingerlings during harvest and their mortality caused by entangment with net algae, Hydrodicton. When used, herbicide treatment was applied before ponds were filled (Aquazine^TM) or as needed during the culture interval (Aquazine^TM) or copper sulfate). Harvesting was done after 24 to 58 days; the extreme range represented variation among hatcheries; the variation among ponds at a given hatchery ranged from 4 to 10 days. Harvest occurred when fingerlings were 25 to 50 mm total length and weighed 1,500-5,440 fish/kg. Harvests ranged from 11,933 to 308,537 fingerlings/ha. Survival ranged from 3 to 104% of the estimated number of fry stocked.     

Litopenaeus vannamei (Boone) post-larval survival related to age, temperature, pH and ammonium concentration

Transport of post‐larvae shrimp used in aquaculture is an important element of successful cultivation because of the potential for stress during stocking procedures. To find optimum transport conditions, several bioassays were performed in the laboratory to evaluate survival of whiteleg shrimp Litopenaeus vannamei 5–30‐day‐old postlarvae under conditions similar to those encountered during transport from the hatchery to nursery and shrimp ponds. Postlarvae were exposed for 4 h to different temperatures and pH levels ammonia concentrations. Survival was significantly reduced after a 4 h exposure to pH 9 and was inversely related to temperature with or without 7 mg L^?1 of ammonia. The 15‐ and 20‐day‐old postlarvae had higher survival rates than other ages. The lowest survival occurred in alkali conditions (pH 9), with 7 mg L^?1ammonia at 30 and 32°C. To assure optimal survival of postlarvae during transfer from the hatchery to the nursery and shrimp ponds, we recommend temperatures below 28°C, pH no higher than 8, no ammonia and post‐larval age at least 15 days.     

Biochemical Composition of Pond Biota, Shrimp Ingesta, and Relative Growth of Penaeus vannamei in Earthen Ponds

Indigenous pond biota contribute to the nutrition of shrimp grown in semi-intensive and extensive earthen ponds. Penaeus vannomei ingesta was used to assess the nutritional contribution of pond biota and applied feed in model 225 m² nominally managed earthen ponds. Biochemical analyses were also performed on representative pond biota and pond environment samples. Average dry matter shrimp ingesta composition ( N = 64) was: available carbohydrate, 4.2%± 1.8%; lipid, 4.8%± 2.3%; available protein, 9.6%± l.0%; carbon, 9.6%± 1.0%; nitrogen, 5.9%± 2.9%. Ingesta carbon decreased from 27.0%± 3.9% on week 2 to 16.3%± 3.3% on week 8, and nitrogen content decreased from 9.5%± 4.3% to 3.6%± 0.8% during the same interval. The decrease of ingesta C:N ratio from weeks 2 to 8 may indicate changing nutritional requirements of the shrimp. Ingesta essential amino acids varied by less than 10% from short-neck clam protein. Except for several samples which were low in arginine, pond biota and environment samples contained amino acid profiles which were close to short-neck clam. Essential fatty acid composition of shrimp ingesta was highly variable. Ingesta 22:6 fatty acid was present in populations of shrimp from ponds experiencing the highest weekly growth rates. Ingesta 22:6 fatty acid was not present in measurable amounts in shrimp experiencing the lowest growth. The unsaturated fatty acids 20:5 and 22:6 were absent from some pond biota and environment samples and abundant in others. The applied diet contained no measurable 20:5 or 22:6. The management implications of shrimp ingesta biochemical analyses are that diets may be fed which nutritionally complement pond biota consumed by the shrimp.     

Effect of Genetic Algorithm Optimized Solar Tunnel Dryer on the Quality Attributes of Thin-Layer Dried Fish

ABSTRACT

Studies were undertaken to establish the performance of a genetic algorithm-optimized solar tunnel dryer in drying of fish by comparing quality attributes of fish dried in the optimized solar tunnel dryer with that dried in a nonoptimized solar tunnel dryer and in open sun. A two-way analysis of variance revealed a highly significant difference between moisture ratios for the fish dried under the optimized solar tunnel dryer and the other methods (F = 53.59, F_crit,1% = 4.09). In addition, thiobarbituric acid reactive substances showed that fish dried in the optimized dryer did not develop rancidity (2.30 µg MA/kg), that dried in nonoptimized dryer approached rancid values (5.3 µg MA/kg), while open sun dried fish was slightly rancid (7.95–8.45 µg MA/kg). Further, based on total volatile base nitrogen, fish under the three drying treatments did not develop significant putrefaction. Furthermore, it took 15, 22, and 28 h to dry fish to equilibrium moisture content of 0.12 kg/kg (dry basis), for the optimized and nonoptimized solar tunnel dryers and for the open sun drying, respectively. Thus, the optimized solar tunnel dryer is superior to both nonoptimized solar tunnel dryer and open sun drying in the drying of fish.     

Growout of Pacific White Shrimp, Litopenaeus vannamei, Stocked into Production Ponds at Three Different Ages

This study was designed to determine the production characteristics of the Pacific white shrimp, Litopenaeus vannamei, stocked into grow‐out ponds at three different sizes and ages. To meet this goal, three groups of postlarvae (PL) were obtained. The first group was placed in a nursery system for 21 d (N21), the second for 14 d (N14), and the third was stocked directly into ponds (DS). Shrimp from each nursery treatment (three tanks per treatment) were pooled and then subdivided for stocking into four replicate 0.1 ha ponds per treatment, another four ponds were stocked directly (DS) with PL₈. All 12 ponds were stocked on the same day at a density of approximately 35 PL/m², and cultured over a 16‐wk period and then drain harvested. After harvest, mean average weights (15.4, 16.9, and 14.9 g), survivals (63, 62, and 64%), FCRs (2.7, 2.5, and 2.7), and average yields (3592, 4005, and 3374 kg/ha) were determined for N21, N14, and DS, respectively. No significant (P > 0.05) differences were observed among treatments. Regardless of nursing time, nursed juveniles did not differ significantly in production characteristics from shrimp stocked directly from the hatchery.     

Effects of food thermal treatment on growth, absorption, and assimilation efficiency of juvenile cuttlefish, Sepia officinalis

The diet of frozen grass shrimp (P. varians) was compared to similar grass shrimp that had suffered either boiling, drying at 60°C, or freeze-drying by lyophilization at −40°C. In experiment 1, cuttlefish fed the frozen shrimp were significantly larger (P < 0.05) at the end of 10 days and at the end of the experiment, compared with those fed the boiled or dried shrimp. Growth rates were also higher for cuttlefish fed the frozen shrimp, compared with the remaining two. Growth rates were also higher for cuttlefish fed the frozen shrimp, compared with the remaining two. In experiment 2, there were no differences in weight (P > 0.05) between cuttlefish fed the frozen or the freeze-dried shrimp, whereas cuttlefish fed the dried shrimp were smaller at the end of the experiment. Growth rates of cuttlefish fed the dried shrimp were lower, compared with those for cuttlefish fed the frozen and freeze-dried shrimp, with no significant differences (P > 0.05) between them. Cuttlefish fed freeze-dried and frozen shrimp showed a higher trypsin activity compared to animals fed boiled and dry (60°C) shrimp. A higher proportion of absorbed energy was channelled into biomass production in animals fed frozen and freeze-dried shrimp (56% and 43%, respectively) than for animals fed oven-dried (60°C) or boiled shrimp. The heat treatment suffered by the shrimp, either dry or wet, negatively affected diet quality, probably due to denaturation, and loss (by boiling) of proteins and amino acids. Additionally, the heating processes may have oxidized the lipids to a large extent, contributing to the loss of the polar lipids (polyunsaturated fatty acids), which are essential for cephalopods as for other organisms. Freeze-drying by lyophilization (negative temperatures) did not affect the nutritional quality of the shrimp.     

Seasonal Trends in Flavor Quality of Channel Catfish,Ictalurus punctatus,from Commercial Ponds in Mississippi

Seasonal trends in types and intensities of fish flavors were determined for channel catfish, Ictalurus punctatus, from 10 ponds located on a commercial farm in west-central Mississippi. Fish were sampled bimonthly from July-September, 1990 and monthly from October, 1990-July, 1991. Sensory evaluation indicated that, on a yearly basis, 19% of ponds could be considered on- flavor. Off-flavors were strongest from July through September when 76% of ponds had fish tainted by 2-methylisoborneol (MIB). In nine ponds, the onset of MIB off-flavor episodes could be correlated with the presence of an MIB-producing cyanobacterium Oscillatoria chalybea. In seven ponds, fish lost the MIB off-flavor within 3 to 8 weeks after the fist date in September that 0. chalybea was noticed to be absent from the water. In June, 0. chalybea reappeared and caused MIB off-flavors in eight ponds. During the winter and spring, ponds were affected by woody (22%) and decay (25%) offflavors. The most prevalent algal species-Raphidiopsis brookii, 0. aaardhii. and Microcystis aeruginosa-were not associated with off flavor problems. On average, MIB off-flavor episodes lasted for 115 days (range: 27-344), and seven ponds were considered free of off-flavors for an average of 74 days (range: 14-140) in October, November, and December.     

Predation on wild and hatchery salmon by non‐native brown trout (Salmo trutta) in the Trinity River,California

Non‐native predators may interfere with conservation efforts for native species. For example, fisheries managers have recently become concerned that non‐native brown trout may impede efforts to restore native salmon and trout in California's Trinity River. However, the extent of brown trout predation on these species is unknown. We quantified brown trout predation on wild and hatchery‐produced salmon and trout in the Trinity River in 2015. We first estimated the total biomass of prey consumed annually by brown trout using a bioenergetics model and measurements of brown trout growth and abundance over a 64‐km study reach. Then, we used stable isotope analysis and gastric lavage to allocate total consumption to specific prey taxa. Although hatchery‐produced fish are primarily released in the spring, hatchery fish accounted for most of the annual consumption by large, piscivorous brown trout (>40 cm long). In all, the 1579 (95% CI 1,279–1,878) brown trout >20 cm long in the study reach ate 5,930 kg (95% CI 3,800–8,805 kg) of hatchery fish in 2015. Brown trout predation on hatchery fish was ca. 7% of the total biomass released from the hatchery. Brown trout only ate 924 kg (95% CI 60–3,526 kg) of wild fish in 2015, but this was potentially a large proportion of wild salmon production because wild fish were relatively small. As large brown trout rely heavily on hatchery‐produced fish, modifying hatchery practices to minimise predation may enhance survival of hatchery fish and potentially reduce the abundance of predatory brown trout.     

Productivity benefits of selectively breeding Black Tiger shrimp (Penaeus monodon) in Australia

Advances in the domestication and selective breeding of Australian Black Tiger shrimp, Penaeus monodon, opens the opportunity for world producers to reconsider the benefits of farming this species. Just over a decade ago this species was the world's most farmed shrimp species, however, difficulty in its domestication, in part, led to the widespread establishment of Penaeus vannamei (Pacific White shrimp) as the most farmed shrimp species in the world. This study empirically evaluates the productivity benefits of commercially domesticating P. monodon against production from wild broodstock of the same species. The evaluation compared the relative production from commercial ponds stocked with the progeny of wild P. monodon broodstock and ponds stocked with the progeny of domesticated stocks. The production data were from 164 ponds of domesticated stocks and 30 ponds of wild stocks, collected over 4 years (2009–2013) from two separate farm sites of the same Australian shrimp farming company. The wild stocks were sourced from the east coast of Australia. The results suggested that the productivity of the selectively bred stocks was 39% greater compared with production from wild stocks given equivalent amounts of feed and other inputs. Furthermore, productivity was additionally enhanced depending on the choice of feeds and whether stocking took place in September rather than later in the year (i.e. in early spring rather than late spring/early summer in the Southern hemisphere). This suggests that there is significant potential to further enhance the productivity of P. monodon farms via integrating advances in domestication, feeds and management practices.     

Effects of Organic and Chemical Fertilizers and Biological Control of Problem Organisms on Production of Fingerling Striped Bass,Morone saxatilis

Sixteen 0.04-ha ponds were fertilized with similar amounts of nitrogen (N) and available phosphorus (P) provided by either alfalfa meal, urea and phosphoric acid, or a combination where half of the P was provided by phosphoric acid and half by alfalfa meal. Half of the ponds fertilized with the combition of nutrients were stocked with adult male common carp, Cyprim carpio, at an average biomass of 168 kg/ha to provide biological control of rooted aquatic plants and clam shrimp, Cyzicus morsie. All ponds were stocked with 25,000 larval striped bass, Morone saxatilis, at an age of D4 (Dl is the day of hatch). Median harvest density and survival were about 100,000ha and 16%. Number harvested was directly related to numbers sampled with a light and dip net at D5 and D8. Low survival was probably related to high afternoon water temperatures (25-26°C) and relatively low morning dissolved oxygen (4.6-6.5 mg/L) when larvae were D5. Stocking larvae at an age prior to swim bladder inflation resulted in an inflation success of 99%. Dynamics of average net photosynthesis, chlorophylla concentrations, and densities of crustacean zooplankton, as well as mean number, biomass, and length of fingerlings harvested were similar in all treatments, regardless of whether the source of P was organic, inorganic, or the combination. Growth rate of larvae from DS to D8 was considered satisfactory (≥0.4 mm/day) with average densities of crustacean zooplankton of 10-20/L. The average growth rate of larvae from D8 to D40 was negatively related to number harvested. A weekly fertilization rate of available P from 28-38 µg/L resulted in satisfactory average growth rate (0.83 mm/day) of decreasing numbers of larvae at increasing ages: D8-D19-150.000ha. D19-D25-125.000/ha, and D25-D40-73,000/ha The presence of adult common carp provided several benefits: effective control of Chara and filamentous algae; a lower average percentage of fingerlings stranded in vegetation when ponds were drained (0.4% vs 10.1%); lower pH; effective control of clam shrimp.     

Yield to Anglers of Spring and Autumn Stocked, Hatchery Reared and Wild, Brown Trout (Salmo trutta L.)

Tagging experiments are described where hatchery over-yearlings and similar sized wild brown trout were spring-stocked in two small angling lakes. This was followed in the autumn with a stocking of hatchery fingerlings and wild fish. The spring-stocked hatchery fish gave the best return to anglers of 9.3% over the first two seasons, while the autumn-stocked hatchery fish apparently suffered heavy over-winter mortality — giving a return of only 1.3% over a comparable time period. Wild fish gave low return rates of 2.9 and 2.0% from spring and autumn stockings respectively, although netting exercises indicated that these survived longer in the lake than hatchery fish. Analysis of the methods of capture indicated that hatchery fish were more liable to be caught by bait fishing whereas fly fishing was the most successful for wild fish. Estimates were made of the relative cost effectiveness of the various types of fish in terms of returns to the angler.     

Costs of Winter Feeding of Channel‐blue (♀ Ictalurus punctatus × ♂ Ictalurus furcatus) Hybrid Catfish

Previous research has shown that winter feeding is beneficial in preventing weight loss and maintaining catfish health. Although several studies suggest the importance of winter feeding of channel catfish, Ictalurus punctatus, less is known about optimal winter feeding strategies for channel‐blue hybrid catfish (♀ Ictalurus punctatus × ♂ Ictalurus furcatus). Three winter feeding treatments (unfed, fed daily, and fed based on temperature‐threshold feeding) were each assigned randomly to four replicate 0.10‐ha earthen ponds. All ponds were stocked with large channel‐blue hybrid catfish (0.96 ± 0.40 kg) at the rate of 3409 kg/ha and fed using a slow‐sink 28% protein pelleted feed. The two feeding treatments showed significantly greater mean weight at harvest, gross yield, and growth rates than the unfed fish after the 113‐d winter trial. Partial budget analysis indicated that additional costs incurred from the additional feed, fuel, and labor costs over the winter in fed treatments offset the additional revenue from daily winter feeding. However, in the temperature‐threshold feeding treatment, additional costs were similar to additional revenues when 10‐yr average prices were used. Results were sensitive to feed prices and spring catfish prices with positive net benefits from winter feeding at fish prices above $1.58/kg and feed prices below $0.286/kg.     

Evaluation of full-fat and defatted maggot meals in the feeding of clariid catfish Clarias gariepinus fingerlings

The nutritional implication of processed maggot meals, hydrolysed, defatted, full‐fat, sun‐dried and oven‐dried, in the diets of Clarias gariepinus fingerlings were evaluated. The nutrient density, proximate composition, gross energy and mineral constituents of the maggot meals were determined. Five isonitrogenous and isocaloric diets were formulated to provide 40% crude protein in which fish meal in the reference diet was completely replaced by any of the following processed maggot meals: oven‐dried full‐fat (ODM), sun‐dried full‐fat (SDM), defatted oven‐dried (DODM) and defatted sun‐dried (DSDM) maggot meals respectively. Fish were fed ad libitum in triplicate treatments for 56 days in glass tanks. Biological evaluations of the fish were based on growth performance and nutrient utilization indices. The result of the nutrient composition analysis showed that processing methods of defattening and drying influenced the nutrient density of maggot meal, with crude protein content ranging between 43.30% and 46.70% for full‐fat sun‐dried and hydrolysed/defatted oven‐dried maggot meals respectively. The result showed that growth performance and nutrient utilization of fish fed DODM and DSDM dietary inclusions were not significantly different and similar to fish fed the fish meal‐based diet. However, fish fed the diet containing SDM exhibited lower daily weight gain, protein efficiency ratio and specific growth. Generally, fish performed better when fed diets containing defatted maggot meals than full‐fat maggot meal, and compared favourably with fish fed the fish meal‐based diet.     

The effectiveness of a commercial microbial product in poorly prepared tiger shrimp, Penaeus monodon (Fabricius), ponds

The efficacy of a commercial microbial product was tested in commercial tiger shrimp, Penaeus monodon (Fabricius), ponds for one culture period in Kuala Selangor, Malaysia. Four ponds with replicates for treatment and control were used. The pond bottom was dried but the organic sludge was not removed as normally practised in pond preparation. The ponds were stocked with 15 post‐larvae at the rate of 31.m^?2. Physical, chemical and biological parameters of the pond were analysed every 2 weeks during the culture period. Water quality parameters remained within the optimum range for shrimp culture except for ammonia‐nitrogen being significantly higher in control ponds and silica in treated ponds. Benthic organisms were not found in any of the ponds. The average counts of different bacteria were not significantly higher in treated ponds than control. Because of poor health, the shrimp were harvested earlier (72 days) than the usual 120 days. An average of 875.60 ± 67.00 kg shrimp ha^?1 was obtained in treated ponds with a feed conversion ratio (FCR) of 1.57 ± 0.10 and survival rate of 42.35 ± 5.37% compared with 719.50 ± 130.94 kg shrimp ha^?1, 2.99 ± 0.70 and 21.25 ± 3.26%, respectively, in control ponds. Neither the microbial product nor the frequent water exchange was effective in overcoming the problems caused by the poor pond bottom.     

Pond Bottom Management at Commercial Shrimp Farms in Chantaburi Province,Thailand

Most shrimp farmers in Chantaburi Province, Thailand, use water jets to dislodge sediment from empty pond bottoms, and wastewater is held for sedimentation before discharge into natural waters. Other pond bottom management practices used by a few farmers are sediment excavation, leave sediment but till entire pond bottom, and no mechanical treatment. All four methods of pond bottom treatment are followed by sun drying for 30 d. Soil organic carbon concentration in ponds following dry‐out seldom exceeded 2%. Although shrimp production in 24 ponds supplied by the same source of water was negatively correlated with increasing soil organic carbon concentration (r = ?0.582), this observation does not confirm a causative relationship. Moreover, in trials conducted at Burapha University, Chantaburi Campus, bottom soil organic matter concentration following dry‐out differed little irrespective of treatment method. Lower soil moisture concentration revealed that dry‐out was more complete with sediment removal than without, but better dry‐out resulted in lower soil pH. Removal of sediment by excavation or flushing is expensive, and natural dry‐out combined with liming and occasional sediment removal should be investigated as a less expensive and more environment‐friendly alternative to removing sediment after each crop.     

Identification of hatchery-reared and naturally produced Atlantic salmon, Salmo salar L., juveniles based on examination of otoliths

. Atlantic salmon, Salmo salar L., parr and smolts from three Norwegian rivers were examined with respect to whether or not they had been released from a hatchery. The hatchery background was known for some released fish and could be ascertained for others from their aberrant body morphology and eroded fins. Fish released after one winter in a hatchery had opaque otoliths like the fish examined from two hatcheries. Naturally produced fish showed a distinct, seasonal growth pattern in the otoliths, alternating between opaque summer zones and hyaline winter zones. Fish released as fry showed an otolith pattern similar to that of naturally produced fish. A test revealed little discrepancy between two independent otolith readings even though the test reading was conducted without any information about the fish accompanying the otoliths. The results suggest that examination of otoliths may help distinguish between juveniles that are hatchery-reared and juveniles that are naturally produced in the river, provided that the hatchery-reared fish have a 1-year history in the hatchery prior to release.     

Impact of farm management on expression of early mortality syndrome/acute hepatopancreatic necrosis disease (EMS/AHPND) on penaeid shrimp farms in Thailand

Asian shrimp farming industry has experienced massive production losses due to a disease caused by toxins of Vibrio bacteria, known as early mortality syndrome/acute hepatopancreatic necrosis disease (EMS/AHPND) for the last 5 years. The disease can cause up to 100% cumulative pond mortality within a week. The objective of this study was to identify factors associated with AHPND occurrence on shrimp farms. A case–control study was carried out on shrimp farms in four provinces of Thailand. Factors related to farm characteristics, farm management, pond and water preparation, feed management, post‐larvae (PL) shrimp and stock management were evaluated. Multivariable logistic regression analysis identified factors affecting AHPND occurrence at the pond level. Chlorine treatment, reservoir availability, use of predator fish in the water preparation, culture of multiple shrimp species in one farm and increased PL stocking density contributed to an increased risk of AHPND infection, while delayed first day of feeding, polyculture and water ageing were likely to promote outbreak protection. Additionally, the source of PL was found to be associated with AHPND occurrence in shrimp ponds, which requires further study at the hatchery level. Identification of these factors will facilitate the development of effective control strategies for AHPND on shrimp farms.     

Pond production of Pacific white shrimp,Litopenaeus vannamei,fed grain distillers dried yeast

The objective of this study was to demonstrate the feasibility of four diets formulated to contain increasing levels (0, 50, 100 and 150 g kg^?1 of diet) of grain distillers dried yeast (GDDY) in production diets for Litopenaeus vannamei, reared in outdoor tanks or production ponds. The production pond trial was carried out in 16, 0.1‐ha ponds using four replicates per diet. Juvenile shrimp (38.1 ± 4.26 mg, initial weight) were stocked at 30 shrimp m^?2 for a 16‐week period. The same four diets and a commercial reference diet were offered to shrimp maintained in outdoor tanks over a 12‐week period. A total of 20 tanks were stocked with juvenile shrimp (3.05 ± 0.22 g, initial weight) obtained from production ponds at a density of 30 shrimp per tank (40 shrimp m^?2). At the conclusion of these trials, mean final weight ranged from 19.77 to 23.05 g, yield ranged between 4760 and 5606 kg ha^?1, survival ranged from 69.6% to 89.4%, and feed conversion ratio (FCR) was between 1.02 and 1.23. Shrimp reared in the outdoor tanks confirmed the results of the pond trial. Mean final weight ranged between 18.12 and 18.97 g, survival ranged from 93.3% to 98.3%, and FCR was between 1.25 and 1.29. In both trials, there were no significant differences regarding mean final weight, FCR and survival among dietary treatments. Based on this study, GDDY up to 150 g kg^?1 of diet can be used in L. vannamei commercial feed formulation.