Koi

Bonnie's Plants - Koi & Pond Specialists
While this is mainly a commercial site where you can purchase koi and pond plants, they also have a lot of useful information on keeping and feeding koi.

Nishikigoi - Koi Indentification and Information
This website has a lot of information about koi. One of the most interesting aspects of this website is their pages on koi identification. They have many koi varieties with photos by variety type (e.g., Shusui, Bekko, Doitsu, and others).

Koi and Pond Guides
Build a fish or Koi pond. Create a tranquil space right in your own backyard. This website shows you how to build a koi pond step by step. It also gives you tips and information to keep your pond and fish healthy and thriving.

Koi Pond Kits
Buyers information on koi pond filters and pond kits.