Yeah you can feed Koi and pondfish some worms, and they're not expensive. In fact, superworms made my Koi very happy for a whole indoor winter. Anyway, here's the guy I get them from.

RE: Earthworms as food for fish - where to get them - how to feed
Hello Doc.
Thank you for linking our site.

We noticed a definite increase in brilliance of color - similar to that
realized by bird and dog/cat breeders who feed a beta-carotene supplemented food. The protein content of our worms is higher than that of a "wild" worm as we feed a 16% protein food.

We have had worms in the 8 oz. cups in which we sell the smaller quantities in our basement unrefrigerated for 15 weeks and they are in excellent condition. We recommend that people not refrigerate their worms.

We ship by USPS Priority Mail and orders are received within 3 days of shipment. The care of the worms is relatively easy and has been addressed by a page on our site entitled "earthworm Care and Feeding". It is linked from our Earthworm page.

Larger Koi can be fed either the European or Tropical Nightcrawlers. Small Koi can be fed Red Wigglers.

Hopefully this will answer your immediate questions, however if you have the time, e-mail me your phone number and the best time to reach you (including your time zone) and I'll give you a call.

Regards,

Carlton Smith
New York Worms
http://www.nyworms.com
carlton@nyworms.com

Carlton Smith - New York Worms