Aquaculture is more than a science in its infancy; it is now recognized as a viable and profitable enterprise worldwide. As aquaculture technology has evolved, the push toward higher yields and faster growth has involved the enhancement or replacement of natural foods with prepared diets. In many aquaculture operations today, feed accounts for more than one-half the variable operating cost. Therefore, knowledge on nutrition and practical feeding of fish is essential to successful aquaculture.
To expand the knowledge on nutrition and feeding of fish, the Subcommittee on Fish Nutrition of the Committee on Animal Nutrition, under the auspices of the National Research Council, has examined the literature and current practices of aquaculture and prepared the latest recommendations on fish nutrition. It presents in this report a broad analysis of the nutrient requirements of various species, appropriate diet formulations and preparation, and feeding practices.
The subcommittee believes that the nutrient requirements derived for several fish species have served adequately as a basis for formulating productive and cost-effective diets for most commercial species. As more information becomes available, the requirements of various species and for specific productive functions will be refined.
Generally, nutrient requirements do not vary greatly among fish species. Any exceptions can often be identified with warm-water or cold-water, finfish or crustacean, carnivorous or omnivorous, and marine or freshwater fish. Therefore, the subcommittee recommends when nutrient requirements are not available that a prudent analogy be allowed to suffice.
Feed contaminants, from both human and natural sources, can dramatically affect the health, growth, and reproduction of fish. Because antinutrients and adventitious toxins are being given closer scrutiny in feedstuffs, the subcommittee believes that a greater awareness of their effects on fish is needed by nutritionists and the aquaculture industry. Solutions to problems, which vary depending on the contaminant, include development of alternative, contaminant-free feeds; alteration of feeding practices; and improvement of feed storage conditions.
Feeding fish in their aqueous environment involves considerations beyond those for feeding land animals. These aspects include the nutrient contribution of natural aquatic organisms in pond culture, the effects of feeding and diet composition on dissolved oxygen and other water quality factors, and the loss of nutrients if feed is not consumed immediately. Fish feeds require processing methods that provide special physical properties to facilitate feeding in water, and variation in feeding behavior requires special feeding regimens for various species. The effects of diet composition and feeding practice on the quality of the effluent from the culture system is also an important consideration.
The subcommittee has updated the nutrient composition of feed ingredients based on information provided by the feed composition data base of the National Agricultural Library of the U.S. Department of Agriculture. A comprehensive presentation of the fatty acid composition of various lipid sources has been included.
The nutrient requirements presented in this report were determined primarily with small fish and represent concentrations affecting maximum growth rate. Fish size, metabolic function, management, and environmental factors have slight to profound effects on nutrient requirements for optimum performance. Thus, these data represent approximations, and the subcommittee recommends that they be used with discretion. The requirement data do not include additional allowances for processing and storage losses, bioavailability of nutrients in feed ingredients, or economic considerations.
Aquaculture as a science and an industry will continue to grow. With increasing consumer demand and declining yields from natural waters, the aquaculture industry will
need to respond with an increasing supply of fish and fish products. These latest findings by the Subcommittee on Fish Nutrition, coupled with future research on nutrition and behavior, will provide the knowledge and techniques necessary to advance the science of aquaculture, ensuring its growth and success as an industry.