The natural diets of most fish are rich in protein, so prepared rations must also have a high protein content, usually between 25-40 per cent. Fats are the most concentrated energy source of the nutrient groups. In addition to supplying energy, fats serve as storage reserves, insulation for the body, cushioning for vital organs, lubrication and transporters of fat-soluble vitamins. Fish feeds most commonly contain 5-17 per cent fat.
The natural diet of most fish is low in carbohydrates; therefore, the maximum level of digestible carbohydrates in fish diets should not exceed 20 per cent. Because wheat and other whole grains are carbohydrate sources, the (sometimes suggested) feeding of corn or boiled wheat is not recommended.
Vitamins and minerals are compounds that are required in very small quantities to regulate certain biochemical or enzymatic reactions in the body. Quality fish feeds will have these trace ingredient requirements listed.
Because of the particular dietary needs of fish, the use of other pet foods is not recommended. For example, lower protein levels and higher carbohydrate or fibre levels in most dog foods make them unsuitable for proper fish growth or maintaining good water quality.
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Oh and all of you guys jumping on AFG - it is Hans' job around these parts to keep us on our toes with crazy ideas. So take a chill pill.