When I was looking for rays did a ton of research. That doesn't look normal and from what I've seen online it looks to be more of a defect than stress.
You say it's eating fine and all sorts so most likely if anything he's very little stressed.
The biggest concern is him eating but that's normal so I would just keep water clean and keep an eye out.
You say it's eating fine and all sorts so most likely if anything he's very little stressed.
The biggest concern is him eating but that's normal so I would just keep water clean and keep an eye out.