Even after eating the same food for 11 yrs? They've been healthy since day 1, until now. They were just little babies when I got them, I fed them other frozen food at first. I didn't know brine shrimp wasn't great.Thanks for the information.
I'm not a fan of pellets and brine shrimp.
Brine shrimp is mostly water. Surprisingly medium-low in nutritional value.
Pellets contain wheat binders. Marine fish don't use much in the way of wheat/wheat products.
So, my best guess is that this is a nutritional issue.