Little and often is the best rule to follow when feeding koi. Koi will always take more than they could comfortably eat which can cause them to become unwell. Overfeeding will also lead to an increase in ammonia and nitrite which if unchecked could be fatal. Also, koi become bolder and tamer if they have worked up a bit of an appetite and will then hand feed.

It is best to feed koi a properly balanced commercial koi food which will have the right amount of nutrients, protein, fat, vitamins etc. In winter koi should not be fed if it is below 10 degrees C as the food may not be digested and go rancid in the koi's stomach. Wheatgerm food is the best food for winter as it is highly digestible and therefore less likely to cause problems. In the spring a higher protein food can be fed so the koi's body can repair itself and start to grow. In the summer, when it is more than 20 degrees C a high protein growth food can be used.

Certain foods can be fed to koi to enhance their colour. There are proprietary brands with various additives such as carotene or spirulina. Carotene affects the red pigmentation and if used at a high concentration will even turn the white to pink ! Spirulina is a type of algae also enhances the red but won't affect the white.

Koi also enjoy livefoods as treats. They will get some livefood from grubbing around in the pond but can also be given foods such as worms and prawns and even tadpoles. The red pigment in prawn shells is also a good colour enhancer. Another favourite of koi is lettuce, large koi will strip a whole lettuce bare. Brown bread is another good treat, but if fed too much can make them fat.