Banded killifish form group shoals. The conditions in which shoaling occurs, the individuals who comprise the shoal, and the size of the shoal are all highly variable. Shoaling can be understood through a cost and benefit analysis. The costs and benefits of group membership are influenced by food availability and predatory risk. Bigger groups allow for better predatory protection, but are not as conducive to foraging because the food will be distributed amongst all of the group members. For smaller groups, there is not as effective predatory protection, but in regards to foraging each individual will have access to more food.