A mouthbrooder, despite appearances, isn't someone with a habitual enbittered pout, but a sort of fish (or, occasionally, frog) which carries its eggs and young around in its mouth.
Cyphotilapia frontosa. Photo by Matthew Miller. (Can you see the babies?)
Mind you, as you can see, that can often be the same thing.
Word To Use Today: pout. No one is sure where this word comes from, but the Danish word pude means pillow.
There are some species where the fathers take on the mouthbrooding, but it's usually the mothers.