Fish as feed inputs for aquaculture: practices, sustainability and implications

76 Fish as feed inputs for aquaculture – Practices, sustainability and implications

minimal salmonid culture in Asia (salmonid production in 2004 was limited to only 22

324, 11 869 and 3 502 tonnes for Japan, China and the Republic of Korea, respectively).

In essence, therefore, the direct use of fish oils in diets in Asian aquaculture amounts

to less than 20 percent of global production, even though Asia accounts for more than

85 percent of total global aquaculture production. However, taking into consideration

that the mariculture production of carnivorous finfish and shrimp is witnessing a

marked growth, this scenario is bound to change.

The fact that most Asian mariculture is dependent on the use of trash fish/low-

value fish entails a minimal demand on global fish oil supplies per se. However, with

the envisaged changes away from the direct use of trash fish/low-value fish in Asian

mariculture, the demand for fish oil in feeds used in this sector is likely to increase.

3.2 Basic feed types

The feed types used in Asian aquaculture are closely related to the intensity of

the culture practices and to the species cultured. It is commonly accepted that all

aquaculture practices can be categorized as extensive, semi-intensive or intensive.

From a feed input/utilization viewpoint, extensive culture practices will not use any

external feed input and the stock will obtain all its nutritional needs from the natural

foods produced within the system, while in semi-intensive systems, the stock will be

provided with supplementary feeds that are not nutritionally complete, and finally, in

intensive systems, the stock will depend entirely on external feed inputs that have to

be nutritionally complete. These practices are a continuum and it is, at times, difficult

to draw a line between intensive and semi-intensive aquaculture. At the lower end of

the spectrum, in semi-intensive aquaculture, feed inputs can be single ingredients (such

as rice bran) or simple mixes of feed ingredients. At the opposite end of the spectrum

will be a more or less nutritionally complete mixture of ingredients that are “cooked”

in some form and fed to the stock as a semi-moist dough (Figure 7), as a crude pellet

or even as a moist mixture. Farm-made feeds fall into this category.

In contrast is the feeding of whole, chopped or minced trash fish/low-value fish in

Asian aquaculture (Box 1). In some cases, low-value fish are prepared in the form of

fish meat and fed to high-value cultured species such as groupers. Trash fish/low-value

fish are used as the only food source for most cultured marine finfish species (such as

groupers, Epinephalidae), as well as mud crabs (Scylla spp.), lobsters (Panulirus spp.)

c. Fish feeding by placing feed

in containers that are hung in

the ponds

FIGURE 7

Sequence of photographs depicting farm-made feed practice on an integrated farm

in Myanmar (species cultured: catfishes)

b. Cooking utensils used to make

a dough consisting of poultry

waste and rice bran. Poultry

waste is generally obtained from

the poultry pens

a. Raw ingredient (rice bran)