I have one figure eight puffer fish in a slightly brackish tank along with 2 Otto's and 2 Siamese algae eaters. A few days ago my puffer stoped swimming around but then a few days later he started again, but now he has stopped eating. I've been feeding him freeze dried krill. When he stopped eating I tried to feed him some peas in case it was indigestion but he won't eat them. Then I tried feeding him frozen shrimp but that didn't work either. He appears to be fine other than that, his fins are a little torn, but thats it. Also he recently started swimming in a weird way, with his body almost vertical. Instead of him swimming Parallel to the ground like he used to he now swims at a 70 degree or so angle to the ground. My water parameters are fine. Should I start putting anti-bacterial medicine in the tank?