Thanks for posting the pics and the updates and such.
I think a lot of these systems (aquaria, paludaria, riparia, etc.) can be pretty forgiving/flexible, so long as you aren't too specific in your demands/goals.
You have a pretty good volume of water, and with the center island like that, you could even make it into something of a stream biotope, by putting some circulation pumps to get the water flowing around the island (if there were some high-current fish you wanted)
It looks big enough that you should be able to put most types of fish in it, plus it's a lot easier to control the water conditions then the air/land conditions (more so with an open build)
I just liked butterfly fish cause it was fun to feed them when I found a bug in the house