When feeding koi there are two trains of thought, one is to feed the food dry and another is to presoak the food before feeding.

Q:

I noticed that goldfish and Koi foods use difference supplements; some of the food supplements are soybean meal and other use corn meal, is there anything wrong with using these supplements?

A:

There has been a considerable amount of research done on soybean meal since 1951 in fish diets. In fish foods, soybeans have been the most promising of all plant proteins for use as a substitute for premium fishmeal (fishmeal is still the most recommended). Soybean meal is regularly used in professional foods such as catfish foods, trout foods, and other pelleted fish foods, but it has restrictions. Because of the presence of several antimetabolites, the most common are trypsin inhibitors: Trypsin inhibitors from soybeans have a crystalline globular protein that has a molecular weight of 21,500.

Because of the trypsin inhibitors, it has been shown to hinder the growth rates of rainbow trout, channel catfish, cyprinid, and other species of fish. It is recognized to produce pancreatic hypertrophy in some farm animals as pigs, calves, and even some household pets such as dogs and Guinea Pigs. There is also evidence that supports the mechanism by which soybean meal reduces growth rate is a lot more complicated than just a simple interference with the digestion of proteins.

Experiments have showed that with cyprinid that conclusively: Soybean meal contains a 10 to15 percent less available energy and lysine than is required for the wellbeing of the animals. The research also concluded that fishmeal contains some unknown growth factors that are missing in soybean meal. It was determine that when working with cyprinid fry, by increasing the soybean meal content of their diets resulted in growth depression. Also that the replacement of fishmeal by soybean meal on an isonitrogenous basis resulted in significantly reduced growth and feeding efficiency in some channel catfish (Ictalurus). Supplementation to the soybean meal with lipid extracts, non-lipid residue, added fraction of menhaden meal or the purified amino acid methionine, cysteine, or lysine did not improve the growth significantly.

Supplementing the soybean meal with the mentioned additives is an expensive way of improving any fish food source. If any sort of soybean diet is to be used for fish, it is important to supplement it with calcium phosphate (CaHPO4 used in pharmaceutical preparations and animal feeds) because of the almost nonexistent levels of this mineral in soybeans and the action of phytin found in soybeans, which binds these nutrients and makes them unavailable.

The use of soybeans as a major source of proteins is superfluous. According to the research, looking for proteins somewhere else is highly recommended. The use of cornmeal is another food additive not recommended for cyprinid, because the fish really cannot digest it very readily and/or not at all. Which create more fish waste to clog filters and decompose in the pond before the bacteria can utilize it as food. However, here is an interesting fact about some Japanese foods like the Hikari Staple Spirulina and Wheat Germ foods; they all contain soybean meal. Then some other foods they make do not contain any soybean meal in their ingredients. Unfortunately, they are not the only manufacture that uses soybean products in their fish foods. For what they charge for these foods, you would not expect in the least soybean meal and corn meal to be an additive.

When feeding koi there are two trains of thought, one is to feed the food dry and another is to presoak the food before feeding.  When presoaking fish foods before it is consumed it will leach some of its nutrients in solution especially vitamins and will then decrease its nutritional value which is no different than when you eat a breakfast cereal with milk. Think of it this way: When the cereal sits in the bowl it begins to lose some of if viscosity and that in turn starts breaking down the cereals sugars and proteins in the milk solution.  When you’re done with the cereal you have this slurry of sweet tasting leftover milk that all children love to drink. This is exactly what happens to presoaked fish food! You feed your Koi this soft food that is easier to consume for the Koi but in turn throw away some very important nutrients and vitamins with the discarded water. Therefore, you’re best off just throwing the food directly into the pond water because when fish food gets wet it already starts the leaching process of its nutrients and vitamins.

  Avitaminosis which is a deficiency of one or more essential vitamins which I did my thesis on can be the outcome of presoaking fish foods before feeding.  Even the lack of vitamin C or its deficiency can cause a fish to go humpback.  It’s not whether the Koi food is dry or presoaked because 1-gram of food is still 1-gram no matter if it’s wet or dry, but the digestibility and the formula of that food that affects the quantity and type of waste the Koi produces not the latter. A Koi’s metabolism is how well it will digest food and at 70º F and above is best, and because Koi do not have a stomach, smaller quantities more frequently is best for better nutritional absorption of foods and promoting good growth. However, indigestible and poorly formulated foods will not be efficiently digested by your Koi and will lead to a higher accumulation of solids and dissolved wastes in solution.

The key word here is metabolism and how healthy your Koi are and water quality parameter must be excellent which then will raise their metabolism and that equals better digestion in the intestines and nutrient absorption with less waste.

 Not all Hikari Koi food is treated equal and some do have soybean meal and cornmeal additives in their ingredients. Just beware of what you’re buying and experimenting with different foods may possibly be your only option.

Photo taken from Internet.

Description of Humpback fish:

The backs of fish becomes contorted AKA: Humpback with the lack of vitamin C. You take a perfectly normal fish and eliminate vitamin C from its diet and in a few months their backs will become humped looking like Quasimodo. Looking very similar to the Red rainbowfish (Glossolepis incisu) back.

Years ago a company showed a Clown Fish (Ocellaris Clownfish) Black, Orange, and White in color on the front of their Marine salt bags. But the clown fishes solid white band lines outlined in black were broken up into smaller segments. They (the company selling the salt) acutely thought they had a new hybrid Ocellaris Clownfish. But what was found out latter was improper feeding Avitaminosis and their salt was not as good as they thought. These clowns should have been culled immediately because of their poor quality. No pun intended! 

Red rainbowfish (Glossolepis incisu) back. 

Read my comment below on why I use Purina Game Fish Chow and not overly priced Koi foods!