Yeah, not sure 2 pairs would fit well in a 15. Also that many ottos, 15 gal not enough to support the algae they eat if you cant get them to eat other foods. Certainly not for 6-8.
I know this is late but I’d do a species only tank with the puffersAny ideas of what I could put in with the puffers then? I'd be happy with just them in the tank but I'm just wondering if there's some sort of bottom-dweller or detritus eater that could work.