The fathead minnow needs at least 10 gallons due to its size and activity level. The male has a somewhat rounded head, especially when in mating condition, hence the name. A color morph of the the fathead minnow is known as the Rosy Red Minnow.
Fathead minnows like to have a cave or plant to use as their home base, and once they feel secure you will see them patrolling the tank. They can be kept in groups, although they may fight a little over favored den areas in the tank.