I've had a few Rays over the years that seem to get gas bubbles and would get enlarged like this from time to time and it would go away within a day or two. They were always larger adults. He's only about 10 months old or so. He's not really breathing very hard pretty sure he's still eating, he's never been crazy about food in general just eats at will, think there's any room for concern. He doesn't float like this all the time, he just floats his butt up and then falls back down.