I only buy very young fish, its easier to acclimate them to tank mates.
Red Devils are kinda like oscars and piranhas mixed, especially when they are under a year old sometimes 2 years old at most. They are messy, they eat alot and they prefer live food and can attack/kill a fish bigger then it. They are known to fight oscars as well.
Once my tank gets over its bacteria explosion ill post pics. keep in mind this is a kids tank, with dads help.