I think i remember seeing somewhere one MFK that when rays are breathing heavily that it could possibly be gill flukes. I have had this ongoing now for several months that my henlei pair have been breathing heavily and i cant seem to figure out the actual reason. I first thought it was because my tanks KH ended up on the floor for a period of time while i was unable to care for it but i don't think it was really that. My water is right in check. My female is the one that breaths the hardest. She is at about a 15" disc and is plump on the rear end. She always has a bit of sunken head that stays no matter how fat she gets. She eats very well and is very active. Id appreciate any input on this. Thanks.