Feeding Koi and choosing Koi food may seem like a simple aspect of the hobby. But with so many Koi food products on the market, Koi food can have a direct impact on their health and growth. Gary Abram sets the record straight...

Easy Koi food mistakes
One very commonly mistaken belief is that Koi will be okay if they’re fed on carp foods. This is completely and totally wrong. Koi are now so removed from normal carp that their dietary requirements differ enormously. While many will argue that their Koi are fine on their chosen food, really ask yourself whether a Koi simply survives or whether it thrives – there is a big difference.

Protein potential
One of the most frequently asked questions with any potential food purchase is that of the protein level. Generally, the higher the protein level, the higher the recommended, and indeed necessary, feeding temperature needs to be.

However, some of the newer foods, while containing quite high protein levels, remain digestible at somewhat lower temperatures. The probiotic range of foods produced by Hikari in Japan, for example, have in this respect turned conventional thinking on its head. All the foods in the range, from the growth type to the winter version, all have similar protein levels.

The protein level of the different versions of this food are present for many reasons other than purely for growth. This has to be acknowledged as the feeding of conventional high-protein foods offered at water temperatures below that necessary for efficient digestion can be very detrimental to Koi.

How it works
Broadly speaking, popular belief is that higher protein foods are normally fed during the warmer months of the year to achieve growth, and lower protein wheatgerm foods are used during the cooler period, due to their ease of digestibility and their ability to maintain health.

Yet it is true to say that there is simply no point in giving a high-protein food in cooler water temperatures as it merely comes out as it went  in– Koi are unable to process it. This is usually evident from large amounts of solid fish waste in the pond and, far more sinister as it can go unnoticed, higher levels of liquid ammonia will be produced by Koi.

On the other hand, there is no problem with feeding Koi higher protein foods at higher temperatures as long as you monitor the usual water-quality parameters. It should also be noted that higher level protein means around 40% protein. Koi will not efficiently process higher levels than this even at higher water temperatures.

Top temperatures
Over the years it has been a popular rule of thumb that wheatgerm foods come into use below 15˚C, although many staple feeds can be used down to around 12.5˚C.

Nowadays though, most experienced hobbyists feed wheatgerm as a base food all-year round and add a percentage of other foods at different times of the year so as to tailor-make the diet of their choice for their Koi. On the subject of staple foods, some of these ‘general’ purpose foods have very broad temperature ranges, with some being used as all-year round foods, with a middle-of-the-road protein content.

Above 15˚C, the higher-protein foods can begin to be added to the lower-protein base food. Always consult the manufacturers’ directions with these higher protein foods, as some are not recommended to be fed below 20˚C. There will be good reasons for this advice from the manufacturers. As an example of manufacturers guidance, the brochure of one very famous manufacturer carries a warning not to be surprised by accelerated growth rates when feeding their wheatgerm food – now there’s a thing!

The amount of feed given obviously depends on the water temperature, but always remember the ‘little but often’ rule, and the fact that you cannot overfeed your Koi, only your pond filter system. Monitor your water quality regularly, especially during springtime, and indeed any period of transition from winter rations to summer feeding levels. As a guide, one-to-two feeds a day is adequate at lower temperatures such as 10˚C and below, so long as that temperature is stable. Do not be tempted to feed your Koi if the water temperature is likely to drop overnight or during especially cold weather. Do not feed at all below 8˚C.

Supplementary food
Many hobbyists use some of the food additive products that have become popular in recent years, and some of these can offer genuine health benefits if used regularly.

Paste foods are superb delivery agents for such additions, but pelleted foods can also be used. It is often just a matter of presoaking the pellets in a liquid made up of pond water and the chosen additive. This is not always as laborious as it seems as you may be able to make several days worth of food at a time. Another additive used by some keepers is montmorillonite clay, which can be added to food in order to help Koi assimilate the food more efficiently.

Special ingredients
All such ingredients take a long time to explore to find out just what benefits may be encountered by utilising them. Also, it has to be established that they have no undesirable side effects when used long-term. All of this research and development work takes time and also large resources of money. Facilities have to be established where such work can be carried out and many obstacles and stumbling blocks overcome. Developing a genuine Koi food is no easy task and what I hope that this article illustrates is that Koi foods are really not all the same. Hopefully some hobbyists will give just a little more time to consider exactly what they feed their most treasured pets.