Not are if this applies but I had a small lawnmower blenny that didn't eat and eventually croaked, I now have a larger LMB that I've had for more than 2months and he would eat the algea off my LR
and would also eat krill that I threw in for my clowns and azure damsels, he was getting fat. I mean big ol' belly, but I recently rearranged my LR
and he's been very shy and lost his appetite for the krill, I think? But I just think it depends on the fish. He is still alive but is not as big as he once was. Best of luck!