Check valve in upper mandibular?

[bulldogg7]

Hey Pam, sorry, oddball question. I'm guilty of stalking my fish. I've noticed a flap of skin just behind the upper lip. Malawis, if it makes a difference. This flap is almost invisible when the fish inhales. But when they push the water through the gill it comes down and seals the mouth off, kinda like a check valve. I've posted this question on my usual forum, googled on the moon even, can't find any info particular to cichlid, closest I came was goldfish. Just wondering if maybe you know what this "flap" is.

[Pam Chin]

Hi Bulldog!

hmmmm you have got me, I am not sure which flap of skin you are talking about!!!! And which species are you observing this on??

Cichlid Power!
Pam