I want to start off this post by saying the following:
I have had 2 clownfish in my tank since Mid April, a Firefish goby since mid May, and a lawmmower blenny since about 2-3 weeks ago. Once I added the blenny, about a week later one of my clownfish started breathing rapidly, but the blenny was fine. I decided to do a last resort and dipped the clown in freshwater for 5mins, which I now believe that it helped due to gill flukes since I saw little specks in the water. The clownfish has since been healthy and eating fine. However, now my blenny has been breathing rapidly since yesterday, so I finally opted to treat the whole tank with PraziPro. Once I treated the tank, within 6 hours the blenny was again grazin and looking normal. However, this morning it was being lethargic, rapidly breathing, not grazing, and had a big white spot on one side of its bod (picture attached). I dipped it in freshwater for 4mins, and now I think its going to die.
That being said, my question is this. What could be causing the discoloration on the blenny, and for it to be changing in the way that it is acting so rapidly?
I have had 2 clownfish in my tank since Mid April, a Firefish goby since mid May, and a lawmmower blenny since about 2-3 weeks ago. Once I added the blenny, about a week later one of my clownfish started breathing rapidly, but the blenny was fine. I decided to do a last resort and dipped the clown in freshwater for 5mins, which I now believe that it helped due to gill flukes since I saw little specks in the water. The clownfish has since been healthy and eating fine. However, now my blenny has been breathing rapidly since yesterday, so I finally opted to treat the whole tank with PraziPro. Once I treated the tank, within 6 hours the blenny was again grazin and looking normal. However, this morning it was being lethargic, rapidly breathing, not grazing, and had a big white spot on one side of its bod (picture attached). I dipped it in freshwater for 4mins, and now I think its going to die.
That being said, my question is this. What could be causing the discoloration on the blenny, and for it to be changing in the way that it is acting so rapidly?

, but here are some pics of both sides of the fish.