I did some impulse buying tonight. I purchased 2 very small puffers. The are a 1/2" long. The tank was labeled "Freshwater Puffers". I think I screwed up. I am placing them in my 30 gallon tank and my nephews are taking the guppies. Should I add salt to this tank to make it brackish? If so how much? I have some instant ocean on hand and can add salt if needed. What's the salinity I should shoot for however? Could you also give me any info on them that you can. The guy at the store told me they are eating tubifex worms, black worms, and baby brine shrimp? Should I feed them something else? What should the temp be??? Any help would be greatly appreciated.