about a 7 gallon fish tank

So i have an extra tank. I was going to make it a small marine for my ostraciid i was going to get for my b-day as most grow extremely slow, but something stopped me. Should i make it a freshwater and and get some puffs or just any ideas would be helpful! Dont worry i would have another tank for my ostraciid.

I wouldn't go marine in a 7 gallon, the salt would fluctuate way too much.
Dwarf puffers are the only puffers that could work in that size tank, don't you already have them though?

Nah. I would just hook up the tank to my current exsisting one so salt problem solved. It woulod only be a temperary tank for a fish abuot 1 inch in size.

I think getting dwarvse would be the best idea.

I think i am going to use it as a holding tank for extra live rock. let it get seeded and what not.