Watch the Barbs, kept in large schools they normally keep themselves but there is always a chance other fish could get the odd find nip, especially a betta male with all his fancy finnage
Paradise fish can be very aggressive, I would pass up on those, we keep rather a few of them, inside and out, I find they are far more active and aggressive in warmer conditions.
And Golden Algae Eaters can be a real pain in the butt when they are older.. very territorial, so just keep that in mind
JMO