Lawnmower hunger strike

[Aqua Splendor]

Hello, I bought this fish 1-2 months ago and he is getting skinner over time, I'm completely desperate with him I don't know what else to do:
- I try 8 different type of source
- I switch him to another tank that have more algea


He swim fine but, I feel when I look his stomach he will die in the next couple weeks

What can I do to open his appetite?
Thank you

 

[Waters]

I assume you have tried other foods such as frozen mysis or pellets? I have had lawnmower blennies that didn't eat algae at all.

 

[Aqua Splendor]

I assume you have tried other foods such as frozen mysis or pellets? I have had lawnmower blennies that didn't eat algae at all.

Yes that why I put the photo with the pellet and frozen food next to him

I also have this for medication:

 

[Aqua Splendor]

Update: I think the KanaPlex worked, his behavior and hunger is much better and is not that flat anymore!