These are an available and popular fish. One could definitely keep a bunch in thereHmm for a tank that small, how about a few pea puffers? They are really cool little oddballs. I have one in my planted tank and he is full of character.
OP is 14, and with all due respect I don't think many teens (myself included) can keep up with the maintenance of fishes such as pipefish. I may be wrong, but as far as I know constant feeding of small live/frozen foods may be needed which is both expensive and sometimes difficult to maintain through things like exams. Just my opinion as a teenager.For me i would go Freshwater pipefish (Doryichthys martensii) , something a bit different
They can actually glide out of the water.