If you’re searching “What Do Koi Fish Eat?” you are either starting a new pond or taking over a pond. This guide is meant to help you understand what they eat and how you can develop a successful and well balanced diet for your prized Koi.
Goldfish and koi (carp) are considered non-aggressive omnivores. They will eat just about anything that won’t eat it first such as algae, worms, snails, insects, plants, etc. This is because they get their nutrition from various food sources, and it isn’t surprising that Koi and goldfish in the wild will rarely have nutrition related issues. Their natural environment has a lot of food sources to meet their dietary needs for growth, reproduction, and developmental maintenance.
A Micro Ecosystem
It is in respect that the regular ornamental pond fish will fail to reproduce nature. The fish load of these ponds or the weight of fish when related to the volume of water is 100% greater than in the wild. It is the diversity and quantity of the aquatic flora and fauna in these ponds, especially a koi pond, that is limited and never balanced with the fish population except where the pond is devoted to plants instead of fish. The average hobbyist can’t expect fish in an ornamental pond to be able to satisfy their needs with pond food alone.
Koi Pond Keeping
This is where pond-keeping comes into play. As a pond-keeper, you are standing in for mother nature to provide the basic diet for animals through daily feeding. It is vital that the daily ration of food will meet the nutritional needs in both ingredients and quantity. At the same time, proper nutrition and diet depends on how your fish feed themselves. The correct feeding process is very important for goldfish and koi.
Although, it is easy to list what may be considered the best foods for your fish, and how they need to be fed, but that advice would have little effect without giving you the background about this process. There are so many alternatives and options out there, and there is more coming.
Cost Of Koi Food
Not to mention, your finances are important too. Food costs can really increase over time, and you may end up spending more than needed to provide for their diets. That is why this article starts with looking at the basic needs of the goldfish and koi. It will also look into the physiological characteristics of digestion and ingestion that are part of the feeding process of goldfish and koi, which will affect the food and feeding. With this information, you can then get suggestions on feeding.
Nutrition and Diet
The basic requirements for goldfish and koi are not much different from other fish. They need protein for growth, maintenance and development. Fats such as lipids are the major energy source. Vitamins and minerals are essential for their metabolic performance. Read more below for details on Koi fish food.
The dietary proteins will provide essential amino acids that fish need by can’t synthesize. The natural diet for fish is rich in proteins. So as a pond-keeper, you have to make sure that protein requirements are met. Failure to do this is obvious. A deficiency in just one amino acid can stop growth, and then the fish will begin to waste away.
Feeding Factors & Variables
There are many factors that will influence protein needs for goldfish and koi. Age is important, as a young fish needs more protein than older fish due to the fact that growth demands amino acids than maintenance of the fish body.
Water temperatures will affect protein requirements. When the temperatures are below 60 degrees Fahrenheit the growth will be slow and protein demands are lower. Protein makes up about 25% of all fish in cooler waters.
The feeding rate will also affect the need for protein. If the food quantity is less than the fish’s appetite, then higher protein will be needed. If the food has a lot of starch or fiber, net protein intake will be reduced. Again a high protein content will be needed.
The content of amino acids and the ability to digest other proteins and sources of protein will vary. So the exact protein source is vital. Fish meal and soybean meal do provide easy to digest proteins while animal meats and corn meal have a lot of hard to digest proteins.
Dietary fat will be the main source of energy for a fish. In the wild, the lipid percentage in the diet varies between 10% to 40% dry weight. Energy requirements depend on the activity level of the fish and in general koi are more active in the wild than in a pond. So 5% to 10% of the diet for goldfish and koi needs to be fatty acids.
Linolenic Acids & Oils
Koi in particular need linolenic and fatty acids. Fish oils such as cod liver oil will be the best sources of essential fatty acids which make up about 25% of the fatty acids but only 2.5% are linoleic acids. In contrast, vegetable oils are low in fatty acids but high in linoleic acids. A proper diet for goldfish and koi need to contain about 1% of both types of oil. Linseed oil is a good source which provides both types of fatty acids.
Vitamins, in small quantities, are great for fish health. For instance, thiamin deficienciescan be confused with insecticide poisoning, which cause body curvatures, instability, equilibrium loss, and eventually death. Biotin deficiencies can look like a parasite infection which causes blue slime, convulsions, poor growth and skin lesions.
Koi can synthesize some vitamins like B12 which reduces the need for dietary foods, but many vitamins need to come through its diet. Minerals are also a big part of fish health. They help to form tissue and basic metabolic functions especially osmotic balance between water and the fluids in a fish’s body. Osmotic diffusion helps fish to satisfy their mineral needs if the water contains minerals such as iodine, potassium, phosphorus, calcium, sodium, sulfate, carbonate, and chloride can be gained from diffusion. But zinc, iron, magnesium and copper need to come from their diet.
Koi & Carbohydrates
Carbohydrates are not an important part of the diet for goldfish and koi. Most ornamental fish suffer from diets that are rich in carbs. Liver enlargements, heart and kidney failure, severe liver degeneration, and excessive glycogen deposits on the liver can be caused from overfeeding of carbs. A safe practice is to make sure that the carb consumption is below 10% daily.
Fish also do not need fiber. When fiber is more than 10% daily, food evacuation from the digestive system is sped up. This reduces the absorption of nutrients in the intestinal tract.
Goldfish and koi evolution has seen that the proper running digestive systems need dietary more in the long run. A single food diet is fine where the fish are removed early in life, but ornamental fish need natural lifespans which need various foods.
There isn’t a single food type, no matter how nutritious is right for a long term diet for goldfish or koi. There aren’t any manufacturers of premium food that would claim that their products need to be the only thing in your fish’s diet. So you need to make the effort to give your fish a varied diet which doesn’t mean switching from flakes to pellets but various types of food like insects, vegetables and more.
It is important to think in terms of a supplemental and base diet for fish. The base diet gives the needed proteins, fats, and vitamins while the supplementary diet gives additional minerals and vitamins plus fats proteins, and variety.