Blenny changing colors

[E249]

I've had by lawnmower blenny for several months and have not had any problems with him. I've noticed that he change color a little, appering lighter and darker. Today he had a red stripe on the back part of his dorsal fin. I have never seen this before and a saw on another sight that it could be because he is scared or dieing, is this true? He is still acting normal, but I did introduce a sail fin tang to the tank today. I checked the nitrate and ammonia levels and they are normal. Should I be worried about him?

 

[E249]

P.S. I have fish only aquarium, I accidentaly posted in the wrong forum.

 

[Animal-Chin]

mine changes all the time. sometime hes almost black while others very lightly colored. i think its normal for a lawnmower to change color but i don't know about the red stripe...

 

[Schism]

My lawnmower blenny changes all the time from a white to a dark almost smoke back color. Ive often seen bits of red and blue spots that are noticeable under certain situations and lighting. Every time i look at him i see color change or something i didnt notice before.

The red is mostly in the large sail fin. Ive never heard anything about color being related to any problem, mine is fat and healthy.