HOw do you massage a fish's tummy? I massage my sons, and i imagine its much different. Sketch (puffer) has a soft tummy, not hard or anything. and it is all softish... i dont want to rub off any of his slime coating so i didnt rub too much. He is gonna be hard to net next time! when he sees mee looking in the tank, he hides in the the caves. what do you do with a constipated fish? I cant dump laxitives in his tank... lol.