Unless breeding this species is surprisingly peaceful and will not predate on fishes larger than a few millimetres in length.
Suitable tankmates are far too numerous to list but include most peaceful species enjoying similar environmental conditions.
For those wishing to attempt a biotope-style community see ‘Habitat’ for a list of some sympatric fishes.
Best avoided are aggressive or territorial substrate-dwelling species, or those requiring harder water.
Some aquarists keep Geophagus spp. alongside freshwater stingrays of the genus Potamotrygon which in many cases has proven successful but in some has resulted in them disappearing at night (!).
G. dicrozoster is gregarious and tends to exist in loose aggregations unless spawning, with juveniles in particular displaying strong grouping instincts.
A group of 5-8 individuals should be the minimum purchase and these will form a noticeable dominance hierarchy.
When maintained in smaller numbers weaker specimens can become the target of excessive antagonism by dominant individuals or the group may fail to settle and behave nervously.