Dietary lipids are animportant source of highly digestible energy and are the only source of essential fatty acids required by fish for normal growth, development and maintaining health.
Tilapia have been shown to require a dietary source of linoleic (n−6) series fatty acids.
Linolenic (n−3) series of fatty acids may also be dietary essential for tilapia, but the required levels have not been determined.
Tilapia do not tolerate as high a dietary lipid level as salmonids.
For juvenile O. aureus×O. niloticus, Chouand Shiau (1996) suggested that a level of 5% dietary lipid appeared to be sufficient to meet the minimum requirement of this tilapia hybrid, but a level of about 12% was needed for maximum growth.
However, a dietary lipid level in excess of 12% depressed growth and increased carcass lipid accumulation in juvenile O. aureus×O. niloticus hybrids.
High levels of dietary lipid, especially those rich in polyunsaturated fatty acids, increase the susceptibility of diets to autoxidation and tissue lipid peroxidation, which have been shown to be responsible for detrimental changes of the
fatty acid composition of tissues.
Tissue accumulation of oxidized breakdown products of lipid can have deleterious consequences for cell and organ functions, as well as depletion of tissue vitamin E concentrations.
The influence of dietary lipid on immune responses and disease resistance of fish has also been demonstrated.