IME, tiger barbs and clown loaches are exelent together. Unless you get a group of hoodlum barbs.:devil:
I like you.
Ave, sometimes you have to try things out for yourself. Tiger barbs are known to be nasty if not in a decent sized school. What I've read is 8min, but, that's something you have to try and see how many it takes for your tiger barbs to not be aggressive.
What's the footprint on a 125? Should be big enough for a looong time, but you may need to upgrade later. Keep in mind, captive clowns rarely meet their adult size of 12"... my guess is because we can't effectively replicate the fast flowing streams they come from, so captive clowns get fat rather than slender.
HTH somewhat