Fish oil is an ingredient sourced from the same small bony fish or fish trimmings as fishmeal. The fish are pressed down to release the fish oil, the fish are then further processed into fishmeal using cooking and drying techniques.
Fish oil is a source of energy, but most importantly it provides the only source of long-chain omega-3 fatty acids, which are essential for fish and human health. Like humans, most fish cannot synthesis long-chain omega-3 fatty acids in the body, so they must be sourced from their food (e.g. in the case of cultured fish, omega-3’s come from the inclusion of fish oil from small bony fish or fish trimmings in feed).
Fishmeal is a high protein ingredient that is made from small bony fish or fish trimmings that are not commonly used for human consumption. It is used in feeds as a source of protein.
These ingredients are sourced internationally from countries such as Peru, Chile, Ecuador, and SE Asian countries and imported to Australia.
Vitamins and minerals
Vitamins and minerals are added to the feeds to ensure that the fish obtain all the nutrients they require. These are the same vitamins and minerals as those used in supplements for humans.
Vegetable protein and oil ingredients
Vegetable ingredients such as wheat gluten, lupin meal and soya protein concentrate are used in feeds as a source of protein. Fish feeds are designed to achieve a balanced amino acid profile, and hence a mix of vegetable proteins are used.
The inclusion of wheat and faba bean are sources of carbohydrate. Carbohydrate in the form of starch is broken down into sugars and is used for energy, which has limited nutritional value for a carnivorous fish species. Instead carbohydrate is required in the manufacturing of the feed to help bind the pellet together making it stable and less likely to fall apart when it goes into the water before it is eaten. It is also required for pellet durability to avoid any breakage or dust occurring when the feed is delivered through a mechanical feeding system to the fish, reducing the amount of smaller feed particles entering the water and decreasing the opportunity for nutrient discharge from the feed into the water before the fish can eat it.
Land-animal protein and oil ingredients
Land-animal ingredients used at Skretting Australia are sourced only from Australia and only from suppliers who are certified by the Australian Renders Association (ARA) and are AQIS export accredited. They are also subject to our own supplier approval program and regular audits by Skretting representatives. The animals used are reared for human consumption; therefore subject to strict quality and food safety controls.
Land-animal protein ingredients are a high quality source of protein, for example poultry meal has a very similar amino acid profile to that of fishmeal, making it a suitable replacement of fishmeal in fish feed for carnivorous animals such as salmon and trout.
Astaxanthin is a naturally occurring carotenoid that wild salmon extract from crustaceans that they feed on. This carotenoid is then laid down in the muscle tissue and transported to eggs during the breeding cycle of large salmonids. Salmon cannot synthesise astaxanthin so in aquaculture, nature-identical astaxanthin is added to the feed.
Table 1. Alternate Sources of Protein that are Being Evaluated or have Potential as Partial or Whole Replacement for Fish Meal in Aquaculture Diets
|Soy meal||Poultry byproducts||Insect larvae|
|Rapeseed meal||Feather meal||Single cell protein|
|Sunflower meal||Shrimp and crab meal||Grasses|
|Oat groats||Blood flour||Leaf protein|
|Cottonseed meal||Fish silage||Vegetable silage|
|Wheat middlings||Meat meal||Zooplankton (krill, etc.)|
Protein (range), %
Table 2 Some Compounds Occurring in Feedstuffs that are Known and/or Suspected of Causing Physiological Abnormalities or Otherwise Impairing the Growth of Fish
|Glycosides||Grass and leaves|
|Phytates||All plant foods tuffs|
|Mycotoxins (aflatoxin)||Cereal-based meals not naturally occurring but produced by microorganisms|
|Cyclopropenoid fatty acids||Cottonseed oil and meal|
|Trypsin inhibitors||Soy and rapeseed meal|
|Mimosine||Leaves (Leucaena leucocephala)|
|Oxidized and polymerized lipids||Fish meal; poultry byproducts, krill meal|
|Histamine and putrescine||Fish meal, primarily tuna|