Balanced Koi & Fish Food for Healthy Ponds

Page Summary:  The perfect koi pond as seen from the Kois perspective is a murky water pond and not as we strive to achieve which is a pond where the pondwater is crystal clear in appearance. It might come as no surprise to learn then that koi are actually reared in what are known as mud ponds... large open ponds with a distinctly muddy colouration but which are rich in minerals or micro nutrients favoured by the koi. Koi breeding which takes place in these ponds (known as Mud Ponds) results in successful breeding and a micro environmemt whre tiny koi can flourish.


Koi nutrition, as opposed to practical, scientific fish keeping aspects like filtration, is a widely debated subject. Unfortunately, many koi keepers are not in a position to question fishfood manufacturers and so-called experts concerning koi nutrition. The outcome is that we are forced to blindly accept the information that we are given.

In an attempt to aid your understanding of koi health and nutrition, this article will look at the key components of a balanced diet. There’s no reason why you shouldn’t be able to examine the ingredients and quantities label on the fish food you purchase and understand the relevance of the information displayed.

How Much is Too Much?

It’s important that you realise how your pond environment differs from the ‘natural’ environment in which you would usually find koi.

In the clay ponds of a koi farm, koi can forage for food all day long at their leisure to satisfy their energy and nutritional needs. In our crystal clear garden fishponds, however, our koi depend on us to give them a healthy, balanced diet.

A balanced diet consists of food from the range of nutrient groups in sufficient quantities.

Just like if we were to overindulge in fast foods, we would encounter health problems – our koi need to be fed a diet that is not deficient in certain nutrients, otherwise their health will suffer.

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The Main Nutrient Groups Proteins

Vitally important for the growth of your fish, protein is also one of the determining factors in the price of koi food. Furthermore, protein plays a significant role in the repair of damaged tissue and the making of eggs and sperm. There are twenty-four amino acids which make up proteins, and koi need ten of these amino acids to be included in their diet, as the rest they are able to manufacture themselves.

Sources of these ten essential amino acids are fishmeal, wheat germ and poultry meal. Young koi that are growing will require more protein, making up approximately 35% or their diet. Older koi, on the other hand, will require less protein which will have to be adjusted according to their seasonal metabolic requirements.


Koi require carbohydrates in large quantities as this food group is their primary source of energy. Carbohydrates and complex sugars like starch are found in vegetables, which are also a source of fibre that aids the movement of food through the gut. Artificial fishfood compared to a natural fish diet will contain less fibre in order to reduce the amount of waste entering the pond.

Ensuring the correct quantities of carbohydrates is important. Insufficient carbohydrates will cause fish to use protein to meet their energy needs, which will be more costly in the long run. It will also cause decreased growth rate and an increased secretion of ammonia. Excessive carbohydrate intake, however, will lead to overweight fish.


Another source of energy for your koi, lipids are also responsible for the development of cell membranes and for transporting fat-soluble vitamins. Less than ten percent of a koi’s diet should be made up of lipids which can be found in fish oil or vegetable oils. Trout pellets, however, are very oily and are discouraged as a primary source of nourishment. Just as in a human diet, it is recommended that you feed your koi unsaturated fats as opposed to the unhealthier option of saturated fats.


Vitamins are required in minuscule amounts, but they remain indispensable for optimum growth and the healthy functioning of koi. Many vitamins are very unstable and can become less potent and effective over time. In this regard, it is always good to check up on expiry dates and to use within the specified time-frame.

Of all the vitamins, vitamin C is one that is deserving of special attention as it is responsible for combating disease and the repair of injured tissue. Koi won’t obtain vitamin C naturally in your garden fishpond, so it is important that it is included in their diet. Vitamin C is also unstable and likely to deteriorate during the manufacturing of fishfood, and you should therefore check that vitamin C is included in a stabilised form in any food that you buy.


Like vitamins, minerals are also needed in trace quantities. They function by supporting metabolic functions and the health of tissue, which in the case of fish is their skin, scales and bones. The primary source of minerals in fish food is ash, but koi are also able to obtain many of the minerals that they require from the pond water.

Healthy Food for Healthy Fish

Whether we’re talking about our own health or the health of our treasured koi, there is no denying the fact that diet plays a fundamental role in good bodily function. Our fish are dependent on us for their nutritional requirements as they are unable to get everything that they need from their environment.

What can you do? Make sure that the food you are feeding your koi contains everything that they need to for optimum health. You can do this by checking the labels of fish food for nutrient and vitamin quantity declarations and for expiry dates. Another aspect to look out for is whether the food contains a pleasing balance of animal and vegetable ingredients.


Dont stress over pond pH and Testing Koi Pond pH

Interpet Koi Pond Test Kit

I will make a few very important points here which should be taken very seriously by anyone contemplating measuring pH in a koi pond and then TAKING ACTION based upon the measured result from testing the koi ponds water. If you test do it reliably... Interpet lead this pond water testing field of the koi keeping hobby

  1. pH of koi pond water will vary depending on time of day measurement is taken and especially if plants are in the pond. This means if you take a pH at 9am it will not be the same as a pH taken at 6pm. This single piece of information therefore must never be the information relied upon to make fundamental decisions
  2. pH is notoriously difficult to measure even in a laboratory with sophisticated instruments let alone in a koipond or fish pond using a piece of litmus type paper or a vial with coloured scales on it.
  3. If you must measure pond pH and this is a great part of the hobby then take the pond pH at the same time every day and plot the result on a graph. So now what youre looking for is not a single pondwater result but rather a pH trend in the pond water that you can use to sensibly consider a pH strategy.
  4. Very high pH in a koi pond is a serious threat to the well being of koi when levels reach about 9.5 because at this pH level ammonia which is a natural metabolic product of the koi and its existence becomes extremely poisonous
  5. It would be extremely rare for a koi pond to reach dangerous pH levels but could well occur in koi ponds with serious algae problems

Articles about koi and fish pond care in winter

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Koi pond heating using gas electric in UK temperature control

Bringing fish and pond and water out of winter into spring

Koi goldfish pond covers over winter. How to look after pondfish

Over-wintering koi goldfish hibernation cold freezing water ice

Koi pond heating using gas electric in UK temperature control

Should I heat my new koi pond this winter. What temperature?

Temperature swings. Koi Goldfish Feeding & water temperature

To Feed or not to feed your pond fish or koi or goldfish

How Do I care For My Garden Fish Pond In Cold Winter

Frozen Koi Ponds & Fish Ponds. Ponds Freeze in Winter. Pond Care in Freezing Winter Weather

Interpet Koi Pond Test KitWhat the Does pH of Koi Pond Water Mean? Should I measure Pond pH