My yellow clown goby has been in the bottom corner of the tank all morning, barely moving. He's breathing, although quite fast, and he seems to be having a bit of trouble doing so.
He also has some torn fins, which seem to heal and then get torn again daily, for the past week or so.
I tried target feeding and some food dropped right by him but he didn't even move.
I've checked all my levels, and everything is good (0 ammonia, 0 nitrite, negligible nitrates, pH 8.1, SG
Everything else in the tank seems fine - shrimp, crabs, feather duster etc.
What can I do to help him?