Bicolor Blenny weird behavior

I have had my blenny for a long time (over a year), and he has always been happy and eating well. He has two spots in my tank that he normally likes to hang out in, both holes in the live rock. However, this morning I noticed he started hanging out on the sand under a under the overhang of one of the rocks. He also is showing signs of stress that don't seem to be going away (white lines perpendicular to his body). He gets these white stripes occasionally when the lights go on and off, or when I put my face up to where he is hiding, but they usually go away in a short amount of time. I have had a decent number of fish die recently, but they were all newer, and I'm wondering if this is more than just the typical stress he shows with the lights. He seems to be eating fine, but just isn't as lively as normal.

I tested my water levels, and the nitrates were between 20 and 40ppm, the ammonia was roughly .5ppm, and the salinity was 1.028 (normally I keep it at 1.026).

Is he going to be okay?

TLDR:
- prolonged white "stress stripes"
- spending time in a completely different area of the tank than usual
- Was rubbing up on the sand earlier today
- seemingly eating fine

 

That ammonia isn't helping at all, typically it should always be at 0. Did you add all the fish at once that recently died? A couple things to consider is your biofiltration couldn't handle the bioload causing die off with ammonia still lingering. That can cause excess stress to your blenny which can in turn cause other ailments to arise like ich. For now I would watch what you feed until your biological filtration catches up and theres no more ammonia in the water.

 

I added them over a period of 6-8 weeks, and it was 4 that died in the tank (cleaned up by cleanup crew) and 2 more that died while in quarantine. It was just this past week (same day as original post) that I noticed the ammonia high. When I took the levels the week before that, the ammonia was totally fine. I just set up a mangrove refugium as well as a hanging basket refugium with chaeto, red dragon, and another type of red hair like algae. I also added some more live rock to my sump (dead corals and such). I'm hoping that will help with the bioload. I have also been stocking with corals, does that increase the bioload too? I guess it makes sense that it would as anything that eats has to produce waste.

My blenny is now in quarantine as of yesterday. He didn't eat when I fed the tank, so to be safe I pulled him and he's still doing okay in quarantine. Thank you for the reply!