Overview

Live food is the ultimate in nutrition but even there you must present your fish with a variety.

  Koi and other pond fish, will relish a variety of live foods, including snails (crush the shell beforehand), earthworms and shrimp. Live foods have the added advantage of leaving very few particles of undigested food behind, unlike prepared foods which can be 35-50% binders and other indigestible matter.

What to Feed

  Earthworms can be fed to the fish all year round, if you can't or wont dig them out of your garden, bait shops will be happy to sell you some and, like shrimp and snails, are high in protein and soon become a favorite treat - a sure way to gain the affection of your koi. Tadpoles from frogs not Toads, are another great treat in spring and summer.

 June Beetles captured in a scent trap bag is an excellent food for larger fish, don't worry about the chitin layer it will pass through. Oh and wet the beetles before pouring them into the pond, the first time I used them they all flew away before they hit the water duh.

  Insects that are knocked down by this apparatus are still alive and stir the fish's natural hunting instincts. Bug Zappers fry the bugs and my fish never developed a taste for them. When using this make sure you are connected to a GFCI circuit since it must be suspended over your pond.

  Silkworm pupae high in fat , imported from Japan, are an excellent source of protein, but should be fed sparingly. Feed these pupae only as an occasional treat, however, as they have be shown to cause a diabetes-like disease in koi.    Chironomid larva and mosquito larva are a popular diet for small fish, though not easily available. 

  Daphnia ('water fleas'), plentiful in earthen ponds, are one of the first foods for koi fry, but tend to be too small for adult koi. Maggots are not recommended as they can carry harmful bacteria from the decaying flesh. 

  Algae while considered a pest is also a good live food but rarely do you have to supplement it in your pond as is multiplies rapidly.

  Do not rely on live foods to form the staple diet for koi however, but offer them as a supplement to the regular diet. If koi are fed on these tidbits alone, there is a risk that nutritional diseases will set in as the result of a lack of vitamins or amino acids.

Other Foods and Treats

  Koi and pond fish will accept many foods thrown to them in their pond, but many of these are of little or no nutritional value and may even harm the fish. Brown bread is acceptable, but white bread made with bleached flour contains a mild form of bleach, which does the koi no good at all. Do not offer beans, or corn, since koi are unable to digest the hard outer casing of these foods. Koi will take lettuce leaves and may also eat duckweed and other plants around their pond with the exception of string algae aka blanket weed, which is too coarse and too well attached for them to pull off the sides of the pond. Oranges, Grapefruits, and Watermelons are a treat akin to candy for Koi, but with little balanced nutritional value, should only be fed only once a week as a treat.

Conclusion

  While Koi and Pond fish will accept almost every type of edible substance, the sad fact is that quite a few are of little or no nutritional value and some may even harm your fish. Live food and a balanced diet is necessary for their optimum health and growth.