Midas Blenny in distress

[LMG1974]

Good morning. I need a little help and advise. This morning I found my Midas Blenny sitting in the sand, it’s colors very dark, like when they are stressed. Has moved a little but in the same general area. I’ve had him for roughly 6 weeks maybe a little less. Always very active, hungry to the point of gluttony and colors very bright. Today looks and behaving like he did the day I took him out of the bag after being shipped to me.
Tried feeding. Completely ignored food. He looked at it but just let the pellets drift past. Tried target feeding a little reef frenzy with Mysis, completely ignored, and that’s his favorite. Usually when I come to the tank with the food container, he’s at the top corner begging for food and grabs right out of the pipette.
Gave a good inspection, no external visible signs of anything. No Ich, velvet, bloating, lesions, breathing normal, nothing I can see. No other fish are or have been bothering him. They all look fine and normal.
Just did a water test with Red Sea and Salifert.
Temp: 78.8
Salinity: 1.024
Ph: 8.2
Ammonia: 0
NO2 : 0
NO3: 2
PO4: 0
Ca: 420
Mg: 1320
All: 8
I’m at a loss here. I don’t know if he’s seriously stressed by something, dying, sick.
Any help or insight would be greatly appreciated.

 

[LMG1974]

I just tried to get a picture, but he relocated himself again and is still on the sand in the back opening of a cave. I can only see his head if I shine a flashlight in there.

Only other thing I can think of is I added a sea cucumber a few weeks ago. It’s one of the Caribbean sand eating ones that are suppose to be relatively safe. It never cleaned the sand but worked it’s way up the rocks and went into a hole in the top back of the rocks. The hole is right next to the one the Midas Blenny sleeps in. Is it possible it released something during the night that harmed him? If it did, will he be okay?
All other fish and coral are fine. The holes are right by the overflow, so toxins may have gone right out and not gotten to anything else.