Theres on 5.5-6in upside down/ sailfin catfish in there. He keeps to himself mostly, upside down under driftwood. Only really comes out for feedings otherwise very mellow. Two black skirt tetras flying around the tank but they dont go anywhere near the puffer unless there's food in the tank. Its a little weird that she was fine after acclimation, and for 5 days after. Tons of personality and buzzing all over, and then all of a sudden this issue. Id think if she was stressed from the shipping the affects would have been immediately noticeable first day.