In my experience, they eat like pigs, so they poop a lot. They are a bit nervous, especially when small. When they get up to 5" or 6" they are not as shy. They also do better in a group. Not too bad as far as bio load. Their poop is rather small, even on grown fish. I have 6 adults in with my silver aro. Larger ones make pretty good dither fish because of their shape and speed. I use to have them in with pbass. Their flash drove the pbass nuts! They never caught one though.
I moved five big $ from a large African tank were they could hold their own, but just looked wrong, to a their own tank in the basement. They freaked. they would bounce off the glass when I had band practice or when you would just walk by. I ended up giving them up for their own good. Nice fish, liked to eat and poop even more.