Breathing gills

OK Guys, hear me out on this one. I have this idea of putting red neon, cold cathode or led lights in my gills. I know this has been done before, but here is where it gets different. I want my lights to fade on and off to give the impression of breathing. I know how to make this work. I'm just having a really hard time finding a single color LED or neon that will fade and fit behind the gills.

Any ideas?

Thanks in advance for any input.