Do Fish Yawn?

scobeyra · Dec 31, 2018

I've seen it randomly from several different fish I've owned over the years. An anthia, a chromis, etc. Fish that were perfectly healthy I would see randomly (maybe once a month at most) do what I can only describe as a yawn.
Just curious if anyone has any thoughts or knowledge on whether they actually yawn like we do, or if it's something else?

andys · Dec 31, 2018

scobeyra said:
I've seen it randomly from several different fish I've owned over the years. An anthia, a chromis, etc. Fish that were perfectly healthy I would see randomly (maybe once a month at most) do what I can only describe as a yawn.
Just curious if anyone has any thoughts or knowledge on whether they actually yawn like we do, or if it's something else?

You bet

Jesterrace · Dec 31, 2018

Yup, Wrasses in particular are well known for yawning. Both my Melanurus and Blue Star Leopard Wrasse do it on a regular basis.

scobeyra · Dec 31, 2018

Interesting! Yeah my yellow coriss wrasse does it from time to time.
I always assumed yawning was a breathing related behavior, but if fish do it without lungs, makes me wonder if it's something else entirely.

saltyhog · Dec 31, 2018

It's not for the same reason that we "yawn". It's a form of aggressive display. In it's extreme form it looks like this.

scobeyra · Dec 31, 2018

saltyhog said:
It's not for the same reason that we "yawn". It's a form of aggressive display. In it's extreme form it looks like this.

Makes sense. I disagree that it's not for the same reason though, as I have some pretty aggressive yawns

Kmsutows · Dec 31, 2018

Also done for adjusting their jaw after large meals for example

mort · Dec 31, 2018

Fish also "yawn" just to stretch their mouths. You see this pretty frequently with predators. Their jaws are the most important part of their anatomy so they need to keep them in good condition.

saltyhog · Dec 31, 2018

scobeyra said:
Makes sense. I disagree that it's not for the same reason though, as I have some pretty aggressive yawns

LOL, I know what you mean.

I don't think the exact reason we yawn is known but it's involuntary. Theories that it increases O2 or decreases CO2 haven't panned out. Some think it may redistribute surfactant to keep lung expansion uniform.

4FordFamily · Dec 31, 2018

saltyhog said:
LOL, I know what you mean.

I don't think the exact reason we yawn is known but it's involuntary. Theories that it increases O2 or decreases CO2 haven't panned out. Some think it may redistribute surfactant to keep lung expansion uniform.

I believe the 02 because I’m one of the few people that yawns after a taxing set at the gym. It makes perfect sense if it provides more oxygen and triggers me to take a deeper breath (and it does).

And to the op, yes fish yawn for displays and to sctretch their mouths. It’s relatively common, but all of that has already been said

Jesterrace · Dec 31, 2018

I agree with the other non-aggressive related expressions as well. Although my Melanurus likes to periodically give my Leopard a hard time, I don't usually see it down when they are near each other. I see it when they are swimming around either after a meal or when they are on totally opposite ends of the tank when they are facing away from each other.

Maritimer · Dec 31, 2018

I've seen lots of fish yawn - in freshwater Corydoras catfish, you'd hardly notice - they just turn their eyes down for a second or so. It's particularly spectacular when an eight or nine foot sandtiger shark does it . . .

~Bruce