I agree with bracekeeper, take care of the water conditions first and then treat for the problem, preferably in a hospital tank.
A good rule of thumb is not to treat in main tank!
I agree with bracekeeper, take care of the water conditions first and then treat for the problem, preferably in a hospital tank.
You have way too many fish in a 30g, especially messy fish such as puffers. One valentini requires a 25g tank just for it (gets to 4 in. in size). The porcupine and the star/stripes get to 18 in. each (require 120-180g min tank size). Also puffers have a tendency to be aggressive to each other- sometimes across species. I am not familiar with keeping clowns or damsels- from what I heard they don't get as big as the porcupine (the larger puffers may eventually eat them-almost all puffers are aggressive to some extent-just because a article states that such a species is more docile, don't assume your fish will be-every puffer has a different personality). Damsels I heard can be aggressive- that can lead to more problems. The ich could easily be from the stress of so many non-compatible fish in such close quarters. Get a bigger or more tanks and separate some of the fish. For more info on puffers check
http://www.thepufferforum.com/forum/ug.php/v/PufferPedia/