| Type | A | B | C | D | E | F |
| Cannot be with | B, C | A ,C, E | A, B, D, E | C, F | B, C, F | D, E |
So if each vertex represents one of the types of fish and each edge connects vertices that are not compatible, what does each color on the graph represent? How does the chromatic number help you to solve this problem?
Make a list of the number of tanks that are needed and the kinds of fish that will be kept in each one.