Stocking issues

Hawkian

Depending on the other fish you're considering for your 30g, I'd say tiger barbs should be kept in groups of 5+. I have 7 of them and if I could redo my tank over I'd probably get more barbs and less of the other fish I have. I can tell you for a fact that a group of 7 barbs is much less aggressive than a smaller number as they disperse their aggression among themselves instead of on other fish.