Stocking a 500 Gallon Monster Tank

Question
Hi Will :)

The tank is a 500 gallon with dimensions 8 x 3 x 3. (That's actually 546 gallons to be exact.) The current stock list looks like this:

1 x Silver Arowana
1 x Flagtail Prochilodus
4 x Rotkeil Severum
4 x Hericthys Bocourti
1 x Giant Gold Gourami
3 x Tinfoil Barbs
1 x Oxydoras Niger

I really want to add a giant "eel" species, and narrowed it down to either a Tire Track or a Fire eel. But I've been told that Fire eels are extremely picky eaters and that they're pretty slow-growers too (which wouldn't work in this tank, the aro would make a snack out of it...) and as for Tire Tracks, I've heard from several people that they're usually never seen! :( What do you think?

If you think I should forgo the eel idea completely, do you think an oscar could hold its own in this tank?

Thanks!
-Myra

Answer
Hi,
is 8X3X3 in meters or feet? thats only 200 gallons if those are feet.

Your stocking list would work if it is for sure 500 gallons. An eel would be fine. My silver arowana lives peacefully with a school of neon tetras but that's pretty unusual. An oscar would most likely work too.

Have fun!