Ok, that's what I thought - I didn't realize they got past one inch...
I'm not sure what the filtering speed is exactly, but its got a pretty good current...that's why I wasn't going to put a betta in it - a male would have to struggle too much against the current.
how about a dwarf puffer then? some are freshwater and some are brackish so be careful abotu which ones you get but they'd be cute in a little hex tank