My Valentini puffer has been in QT for about 3 weeks and I've noticed what looks like tiny bubbles stuck to the underside of his belly. He seems fine, eats well, and doesn't appear to be affected. I really have no idea what it is and I'm not sure if I should be concerned. Any advice would be appreciated. Thanks!

Here's a picture, but it's really hard to see

Here's a picture, but it's really hard to see