Let's talk housing: Think very, very big. I suggest no less than 30,000 gallons for an adult and 50,000 gallons for two or three. Swimming area is the key when designing a pool. Depth doesn't have to be much more than about 6 feet. I wouldn't got any narrower than about 10 feet across at any point in the pool. Corners are bad, so all edges should be rounded. Even round the side walls to the bottom. Doing that will also aide in keeping water moving as well. Substrtate should be a natural color, and fairly dark. Brown tones work best. I like to use a mix of small gravel as well as larger fist-sized stones (I'll get into why in a post about breeding.) Tank decor can be basic, but there needs to be something. I've found arapaima to be territorial during certain seasons, so having objects (like logs and boulders) aide in creating a comfortable area for the fish to live. Lighting should be from above. It's been my experience that arapaima do not like underwater lights at all. The pool should have both light and dark areas during the day. Edges fo the pool should be high. These guys are amazing jumpers, and you should consider that one might jump out of the water.
