Common Groups & Species

There are more than 11,500 known species of freshwater fish. Learning about even the most popular types may seem overwhelming, but content in this chapter will help, combined with time on the sales floor and talking with your supervisor and experienced coworkers.

Body shape, markings, fin structure and coloration are important indicators to distinguish between groups of related fish and identify specific species. This module includes information to help you identify the most common species sold in pet stores, and also provides important details about water quality, water temperature, diet requirements and other useful information.

Each species listing includes a Maintenance Rating to help you determine whether a particular fish is a good fit for each customer’s experience level and aquarium set up. Ratings are based on the following scale of 1 to 5, with fish rated 1 or 2 best for beginning hobbyists:

1. Peaceful, mixed community, small adult size (under 4”); average water conditions, beginning hobbyist species.
2. Peaceful to moderately aggressive, mixed community, medium to large adult size (over 4”); average water conditions, beginning hobbyist species.
3. Moderately aggressive, mixed community, average water conditions, intermediate to advanced hobbyist species.
4. Aggressive, special community or single species, advanced hobbyist species.
5. Special concern or requirements.