I think it is just a type of stress stripe of some form....on of my boys gets it, too! And it's only when he flares....and it goes away as soon as he chills out. Noticed it the first time he flared....it's just common for him!The red are just when he flares/on his gills/beard whatever you wanna call it. He has red for the fins also. I dont get how it could be ammonia poisoning, I keep his bowl really clean... He's really active also, big bubbler for nest.