Proteins are the major organic material in fish tissue. Protein makes up about 65 – 75% of the total dry weight tissue.
Fish consume protein to obtain amino acids.
There are 22 amino acids. 8 are considered essential amino acids. These essential amino acids cannot be synthesized in the body and have to be taken in from a food source. The other amino acids can be synthesized but are not always synthesized and also need to be taken in from a food source.
There are a number of other amino acids but I doubt if it is as many as Marius mentioned.
Protein sources in fish and animal feeds. There are many protein sources that nutritionists call on to make a food. Most feeds are a combination of several protein sources. For example protein sources in a feed may be chicken meal, fish meal, gluten, plant protein sources, soya meal. (Chicken meal is usually found in cat and dog food with a sprinkling of fish meal). The nutritionist juggles these various protein sources around until he or she get to the desired amino acid profile for the animal they are formulating for.
Chicken meal in koi food is not a good ingredient. This has to do with the oils found in chicken meal as opposed to the oils found in fish meals.
So if cat food has herring meal – sure – but we do not know the percentage. It could be 1 or 2%. A perhaps just a smidgen ........
Herring meal is used in fish foods but why is herring meal not so common in koi foods – cost and availability. If all your protein was sourced from herring meal only then your final cost of your pellets would be much higher than now.
Poor quality fish meals are available and they have anything up to 55 and perhaps 60% protein. (Fish meal is sold on the world market according to percentage of protein and the way it is prepared). Better quality fish meals have around 65% protein. Herring meal has 78% protein. The price jump between 55% protein fish meal and 65% protein fish meal is substantial so the price jump to 78% protein is massive.
It has been a great concern to nutritionists in recent years is that the equality of fish meal is varying greatly in quality and price in recent years. Supply has also become quite erratic. This is due to overfishing of the natural resources in the ocean. The price of anchovy fish meal rose more than three fold in price between 2005 and 2009. Krill meal is more than double the price of a good quality fish meal. I am not sure of the price of herring meal but it will be much higher than your good quality fish meals.
If you want to buy a bag of herring meal you can do so. But be prepared for a divorce! It smells – well like fish meal. You need to keep it away from moisture and light. It will last a long time dependin gon teh number of fish you have and probably go rotten before you have used the bag up. Further you need to mix it in with a lot of other things as the fish meal will break apart as soon as it hits the water.
The protein in the meal will be nitrogen in the pond water and this will add greatly to the load on your filter system just as any uneaten food will. The fish meal sitting in various places in the system may build up to the point of poisoning your collection (This has happened to the founder of the Koi Society – Terry Sole many years ago).
Shark organs may contain great amounts of nutritious substances – but vast quantities of raw materials are needed to supply the pet food industry around the world. You would have to fish every single shark out of the sea to supply perhaps one months supply of protein for the pet food market let alone for human consumption. (And that’s a real flyer of a guess).
Some interesting facts: There are some 2,000,000 ponds in the UK. 10% of the estimated 80,000,000 households in the USA have ornamental fish – that’s 8,000,000 households with fish! 14% of all households in Holland have fish. Germany has more ponds than the UK.
Hope this helps.