The rapid growth of finfish and crustacean aquaculture has been due in part to the availability and on-farm provision of feed inputs within the major producing countries. If the aquaculture sector is to maintain its current average growth rate of 8 to 10 percent per year to 2025, the supply of nutrient and feed inputs will have to grow at a similar rate. While this may have been readily attainable when the industry was still in its infancy, this may not be the case in the future as the sector matures and grows into a major consumer and competitor for feed resources.

It is estimated that about 29 million tonnes of farmed fish and crustaceans (44.5 percent of the total global aquaculture production in 2007) is dependent upon the supply of external nutrient inputs provided in the form of fresh feed items, farm-made feeds or commercially manufactured feeds. Total industrial compound aquafeed production has increased over three-fold from 7.6 million tonnes in 1995 to 27.1 million tonnes in 2007, with production growing at an average rate of 11.1 percent per year. Aquafeed production is expected to continue growing at a similar rate to 70.9 million tonnes by 2020. Although current estimates for industrially produced aqua-feed production for the period 2007–2010 vary between 24.4 and 28.9 million tonnes, aquafeed volume represents only 4 percent of total global animal feed production of over 708 million tonnes in 2009. In contrast to compound aquaculture feeds, there is no comprehensive information on the global production of farm-made aquafeeds (estimated at between 18.7 and 30.7 million tonnes in 2006) and/or on the use of low-value trash fish or forage fish species as feed, with current estimates for China in 2008 ranging between 6 and 8 million tonnes.

Feed-fed aquaculture production and in particular, the production of higher trophic level finfish and crustaceans (shrimp, salmonids, marine finfish, eels, etc.) are largely dependent upon capture fisheries for their major dietary source of protein and lipid. For example, in 2007 the aquaculture sector is estimated to have consumed 3.84 million tonnes of fishmeal (68.4 percent of total global fishmeal production) and 0.82 million tonnes of fish oil (81.3 percent of global production for that year). However, despite the continued dependence of aquaculture production upon the use of fishmeal and fish oil, there is wide variation in fishmeal and fish oil usage between major producing countries for individual farmed species. This variation mainly reflects differences between countries concerning the selection and use of fishmeal and fish oil replacers from plant sources or the use of land animal proteins and fats within feeds for high trophic level fish species and crustaceans.

In total usage terms, it is expected that the use of fishmeal by the aquaculture sector will decline in the long term, decreasing from a high of 4.2 million tonnes in 2005 to 3.8 million tonnes in 2007 (or 14.2 percent of total aquafeeds), and expected to decrease further to 3.7 million tonnes by 2020 (or 5.2 percent of total aquafeeds). The reason for this is due to decreased fishmeal and fish oil supplies resulting from tighter quota setting and more controls on currently unregulated fishing, and the increased use of more cost-effective dietary fishmeal replacers. The use of fish oil by the aquaculture sector will probably remain at around the 2007 level (0.82 million tonnes or 3.0 percent of total feeds), and increased usage will shift from salmonids to marine finfish and crustaceans, due to the current absence of cost-effective alternative lipid sources rich in long-chain polyunsaturated fatty acids. Increasing volumes of fishmeal and fish oil are likely to come from fisheries by-products, extracted from both wild capture and farmed fish. Currently estimates have been made that around 25 percent of fishmeal production in 2008 came from by-products, and this will continue to grow as it becomes increasingly viable to process this material.

It is estimated that the total usage of terrestrial animal by-product meals and oils within compound aquafeeds ranges between 0.15 and 0.30 million tonnes or less than 1 percent of total global compound aquafeed production – clearly there is considerable room for increased usage. In addition to meat meal or to a lesser extent meat and bone meal, ingredients such as blood meal, poultry by-product meal and poultry oil have all been very effective in feeds for a number of aquatic species.

Soybean meal is currently the commonest source of plant proteins used in compound aquafeeds, with feeds for herbivorous and omnivorous fish species and crustaceans usually containing from 15 to 30 percent soybean meal, with a mean of 25 percent in 2008. In global usage terms and based on a total compound aquafeed production of 27.1 million tonnes in 2007, it is estimated that the aquaculture feed sector consumed about 6.8 million tonnes of soybean meal (25.1 percent of total compound aquafeeds by weight). Other plant proteins that are being increasingly used include corn products, pulses, oilseed meals) and protein from other cereal products.

Alternative lipid sources to fish oil are being used in greater amounts. Key alternatives include vegetable oils, preferably those with high omega-3 contents and poultry oil. The use of oil from farmed fish offal is also a potential omega-3 source for other farmed fish. The production of marine microalgae or bacteria with very high contents of highly unsaturated fatty acids is currently expensive for use in most aquaculture feeds but as production methods become more cost-efficient, the situation is likely to change.

Prices for food and feed ingredients have been increasing and are likely to continue to increase due to increasing demands from the increasing population, diversion of some grains for use in biofuels, increasing costs of production and transport, and changes in global trade. The focus on carbohydrate-rich fractions for production of biofuels may indeed provide an opportunity to use protein fractions for feed ingredients.

Although the current discussion about the use of marine products as aquafeed ingredients focuses on fishmeal and fish oil resources, the sustainability of the aquaculture sector is more likely to be linked with the sustained supply of terrestrial animal and plant proteins, oils and carbohydrate sources for aquafeeds, particularly so because a significant proportion of aquaculture production is of non-carnivorous species. Therefore, aquaculture producing countries should place more emphasis on maximising the use of locally available feed-grade ingredient sources and move away from the use of potentially food-grade feed resources.