Using this Field Guide
This electronic field guide to fishes is meant to be just that: a field guide. Take it with you in the field on class field trips, vacations, or if you are a professional biologist, take it with you every time you leave the office. It is meant to be your first resource for quickly identifying species, confirming characteristics on specimens you are unsure about, and a reference for current info on the status and distribution of fishes in Colorado. Check the website for updates periodically to maintain the most current information. For more detailed descriptions of species consult one of the many print guides to fishes (e.g., Woodling 1985, Page and Burr 1991, Baxter and Stone 1995).
If you think you know the species but want to confirm by seeing a picture and list of key characteristics, or you have a fish that you can place in a family, but you are unsure of its genus and species, select "list of families" and click on the appropriate family name. From there you can see a list of all the species in that family that are known to occur in Colorado, as well a dichotomous key to species. Each species link takes you to a list of distinguishing characteristics for that species, and in most cases a full color image of a live, adult specimen. The origin of the fish can be found in parentheses following the species name: (N) if the fish is native to Colorado, and (I) if it was introduced.
If you have a fish that is completely unknown to you, then select "key to families" and follow the dichotomous key to the determine the family. Then proceed as above to determine the species. To see a list of rare and endangered native fishes in Colorado select "rare fishes".
When you arrive at the species you think is correct, look for the "similar species" link. Flip back and forth among the similar species to confirm you identification.
Abbreviations
Several abbreviations are used to denote anatomical characters: