Chalceus is described to be active, schooling fish that live in high oxygen, fast moving water in their natural habitat. But in the confined space of a fish tank, they are inactive and don't school, but can dart at explosive speed when startled. I've observed macrolepidotus in a million gallon public aquarium, and they cruise solo on the water surface at steady slow pace with no interaction with one another. My macrolepidotus maxed out at 10 inch, stay mostly motionless at one place, and never show aggression nor predatory behavior towards small fish. My yellow fin had the same demeanor but grew bulkier and would likely reach 12 inch if he were still alive. Yellow fin and macrolepidotusare are two different species, and most aggressive behavior reported on macrolepidotus may not necessarily be applicable to yellow fin.
