I've noticed that when my botai loaches yawn sometimes immediately after they will extend their sub ocular spines. That is the only time I ever see them, kinda scary looking. Looks like a yawn followed by a stretch, very similar to what alot of mammals do.
I see my Aro yawn way big right before he eats crickets...
Seems like if it is alive and kickin' he warms up the old trap, sneeks up on it, pauses and then SnaP!
Does a pleco too phat to stick to the glass count?
This dood rubs the bottom with that belly
All my cichlids from jags, dovii, gold motas, red tiger motas, jd, africans, midas, rd, all yawn. They seems to yawn like we humans do, when bored or feeling nappy.
It has nothing to do with nitrites/nitrates.