In the aquarium the marble headstander is generally a peaceful inhabitant despite its (extremely distant) relation to the pirahna. They are completely docile as juveniles both towards other fish and members of their own species. Once older keep either a single headstander or a group of seven or more in a tank as they tend to fight amongst themselves in smaller groups. They are still generally peaceful towards other fish.
Keep marble headstanders in a rocky, heavily planted aquarium with many cracks and crevices for them to explore. Note: if there is not enough vegetation in its diet, it will devour aquarium plants. On the other hand you can use this to your advantage if you want to set up a "self-sustaining aquarium.