Much of the criticism leveled at aquaculture (e.g., dependency on animal‐derived feedstuffs, nutrient‐laden effluent discharges, and increased organic contamination in edible products) can be traced to the feeds in use. Accordingly, finfish nutritionists are being challenged to formulate feeds that not only meet the nutritional requirements of livestock but also minimize production costs, limit environmental impacts, and enhance product quality. These challenges not only add considerable complexity to finfish nutrition but also afford opportunities to avoid some of the mistakes made by other industries in the past. From a review of the current status of finfish nutrition with respect to major nutrient classes, we comment on future opportunities and promising avenues of research. Alternative protein sources, specifically those derived from marine bycatch, plants, and microbes, are discussed, as well as methods to facilitate their implementation in finfish feeds. Dietary lipid, its role in fish bioenergetics and physiology, and quality of aquaculture products is reviewed with special emphasis on alternative lipid sources and finishing diets. Carbohydrates and fiber are discussed in terms of nutrient‐sparing, least‐cost diet formulation and digestive physiology. Micronutrients are reviewed in terms of current knowledge of requirements and, along with other dietary immunostimulants, are given further consideration in a review of nutriceuticals and application in finfish feeds. The status of nutritional research in new aquaculture species is also outlined. By integrating classical approaches with emerging technologies, dietary formulations, and species, finfish nutritionists may identify means to increase production efficiency and sustainability and provide for the continued success of aquaculture.

Aquaculture of yellow perch (Perca flavescens) has been increasing, yet there have been few nutritional studies and no evaluations of alternative protein sources in diets. Solventextracted, dehulled soybean meal (SBM) and expelledextruded soybean meal (exSBM) were fed to yellow perch to evaluate their effectiveness in replacing dietary fish meal (FM) in isonitrogenous practical feed formulations. Both soy ingredients were incorporated in graded amounts from 100 to 730 g kg )1 of the diet. Feed consumption, weight gain, feed efficiency (FE) and survival were significantly affected by type of soy ingredient, concentration and the interaction of the two main effects. Consumption was significantly lower in fish fed diets containing 400, 600 and 730 g kg )1 compared to fish fed diets containing lower concentrations. Weight gain was significantly lower in fish fed diets containing 600 g kg )1 and FE significantly lower in fish fed diets containing 500 g kg )1 compared to fish fed the control diet or lower concentrations of soy ingredients. Most fatty acid concentrations were affected by feeding exSBM compared to fish fed the control diet, but long chain fatty acids remained at relatively high concentrations. Based on feed consumption, weight gain and FE data, yellow perch are able to effectively utilize both soy ingredients in practical diets. A conservative recommendation of 300 g kg )1 diet appears appropriate for growout diets. KEY WORDS

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To facilitate economical culture of black pacu, Colossoma macropomum, and red pacu, Piaractus brachypomus, in the Amazon region of South America, we assessed locally available alternative energy sources for practical diets. We tested the effects of control diets (containing wheat products) versus diets with different Amazonian feedstuffs (yucca, Manihot sculenta, plantain, Musa paradisiaca, or pijuayo, Bactris gasipaes) on the performance of the pacus in three feeding trials. Black pacu (22.5 6 0.03 g; Trial 1) or red pacu (2.56 6 0.01 g; Trial 2) were fed diets containing 30% wheat bran (control) or cooked or uncooked yucca, plantain, or pijuayo for 12 wk. In Trial 3, larger black pacu (86.9 6 6.4 g) were grown to market size in 24 wk on similar diets. Weight gain, feed conversion, survival, alternative complement activity, and lysozyme were similar among diets. Hepatosomatic index, liver glycogen, and dry matter were affected by diet in Trials 1 and 2, but effects were not consistent among trials. In Trial 3, protein efficiency ratio was lower in fish fed the diet containing wheat middlings. However, relative to wheat bran or wheat middlings, all feedstuffs tested were effective energy sources for juvenile black pacu and red pacu.

We conducted a study to explore the effects of phosphatidylcholine (PC) in diets fed to juvenile Nile tilapia Tilapia nilotica (mean initial weight ϭ 12.4 g). The basal diet contained 32% crude protein supplied by casein and gelatin (10.1%) and a crystalline L-amino acid mixture (21.9%). The total sulfur amino acid concentration of the basal diet was 0.5%, the methionine: cysteine ratio was 94:6, the choline concentration was 0.3%, and the linoleic acid concentration was 1.1-3.3%. Graded levels of PC were added at the expense of lipid to the basal diet, resulting in seven dietary treatments (0, 0.25, 0.50, 0.75, 1.0, 1.5, and 2.0% of the dry diet). The graded additions of PC significantly affected the weight gain and feed efficiency of juvenile tilapia. The weight gain of fish fed 1.5% and 2.0% PC was significantly higher than that of fish fed lower concentrations, and the feed efficiency values were highest in fish fed 1.5% PC. While total liver lipid concentration and survival were not significantly affected by dietary PC, whole-body crude protein and lipid concentrations were significantly affected, although there were no clear trends in this regard. Therefore, based on weight gain and feed efficiency, we conclude that PC is a beneficial nutrient for tilapia and recommend that purified diets fed to juveniles include 1.5% PC.