A small Indonesian fish is covered in black spots in anger

Males without black markings were attacked by both females, colorless males, and males with black markings. Females in the tanks were subjected to the same level of attack as males.

Overall, the team suggests that, given the attacks between all fish, it is likely that they are competing for resources rather than partners. Individuals with markings are the most aggressive. The reason for the latter may be to signal dominance and fighting ability, as well as a willingness to defend themselves.