I'm in the process of buying an aquarium that comes with fish. It is a freshwater setup, mostly cichlids and silver dollars. There are two monos, one Argenteus and one Sebae. They are around 6" to 7" and look fantastic.The aquarium is large, 680 gallons, and well decorated with plants, boulders, and wood. The current owner said that basically, once a fish goes in the aquarium it is almost impossible to get it out. So, before putting the monos in, I want to make sure they will do fine long term (their life-span) in the freshwater setup.