I'd say nothing smaller than 30,000 for a single arapaima. Anything less then that and you will see growth stunting and major heath issues only a few years into it If you want two or three, you can do it in 50,000. Horizontal space is more important than depth. But avoid something too shallow. At least 7" depth for them. They will use at least that much if they take a larger breather and diver down with it. I've seen it a lot. Also, in the wild, they spend a lot of time "laying" on the bottom to rest. That depth needs to be deeper than the swimming depth. They need the length to get into full stride while swimming. If they don't have that, muscles won't develop correctly. Improper muscle growth leads to spinal issues after about a year. That leads to an animal that can't swim properly, and therefor can't get to the surface to breathe as it should.
/QUOTE]............
Yeah, ok, well then, leave me nothing to add, LOL.
--EMI