It is easy to miss the dp tank, you really have to ask. last time they were by the corydoras
full answer is 5 gallons for the first puffer and 3 gallons for each additional, but I really question this. This is for aggression purposes only, as far as I can tell.
After watching mine, and watching the males fight here is what I think. My opinion not fact.
you could keep 10 females in a 10 gallon with no problems ever
2 females and one male would be better than 1f and 1 m, less harassing of each female
if there is a female in the tank and there are more than 1 male then the weaker male will probably suffer. especially in a smaller tank
females ignore each other for the most part
immature puffers like to hang out together
mature males fight violently.
they don't have a territory that I can tell, it is all about having enough stuff in the tank for the weaker one to get away.
males will follow females all over the tank trying to put the moves on her.
well fed puffers seem less nippy towards one another.
20L My Other Tank: OEBT Shrimp
40B Inlaws Tank: 2 goldfish
75 Main Tank w/ sump: 5 Glossolepis pseudoincisus, 5 Melanotaenia boesemani, 10 Melanotaenia praecox, 5 Melanotaenia lacustris, some cories, a bn pleco and rainbow fish fry