answer:It’s not really so much as how many fish you have (especially when talking about only three) but what each fish needs Surgeonfish and Tangs generally are recommended a minimum of 75 gallon tank for an adult Three Striped Damsels are recommended 10–15 gallon for one Clownfish are recommended anywhere between 10–30 at least but universally it seems to be stated that the larger the better for these jokers. So looking at this, you’re looking at a minimum of a 75 gallon tank. I think some more fish to keep them company isn’t to bad of an idea