USE OF MANURE IN FISH FARMING - REVIEW

The use of manure in aquaculture, as practised for centuries in the Far East, is compared with the use of ordinary feedstuffs. Maximum yields per unit area are higher with high-protein feeds than with manure, but are obtained at a greater cost. When manure is a regular input in aquaculture, problems of manure disposal are largely avoided and integrating aquaculture with animal husbandry appears to result in the most rational manure utilisation. In the Chinese system of growing fish on manure a number of different fishes are grown together. Profits per unit area and time are higher with the use of feedstuffs when fish are relatively expensive, but when fish are cheap higher profits are obtained with manure. This has led to fish being the cheapest source of animal protein in large parts of the Far East. When manure is applied to fish ponds, best results are obtained with frequent applications. Incorporating manures into high-protein feeds appears to lead to a reduction in growth rates and does not, as a rule, reduce feed costs per unit weight of fish produced. The food web, leading from the manure applied to the fish-flesh produced, is discussed in terms of direct feeding, source of minerals for autotrophic production and source of organic matter for heterotrophic production. © 1979.