Do fish yawn?

[AdamHorton]

I've noticed my fish doing something that looks just like yawning, but from what I know about humans yawning and how it regulates the pressure near their ears, I can't quite apply that to fish.

Are fish yawning, or are they doing something else when it looks like that?

 

[melosu58]

I have seen that also but I cant give you an answer as I really dont know. Sure looks like it though.

 

[Deep Seven]

Depends on the fish. Some species of fish are filter feeders and flush extra water through their mouths to collect food, and that will look a lot like yawning. Water flow into the mouth and out through the gills is how most fish breath, so if they need extra oxygen they can flush extra water through their gills. This can allow them to "breath harder" without swimming faster. Fish consume more oxygen while digesting food, so this behavior could be more prevalent after feeding.

If the yawning is rapid, more like gasping, then they're probably having trouble breathing, either low oxygen, or something preventing the fish gills from working properly, ie.: high ammonia.


Edit:

from what I know about humans yawning and how it regulates the pressure near their ears

Just some fun facts. I've heard yawning also cools the head a little bit from the evaporation in the mouth, and the slightly cooler temperature helps you think clearer. Also a good yawn helps replenish oxygen in the blood and that also helps you think clearer. When you see someone else yawn, your body/subconcious recognizes it, and stimulates a yawn so that you can also perform better at whatever activity you're engaged.

 

[AdamHorton]

I notice it a lot in my Bangai Cardinals, damsels, and in some danios I have in my FW tank too. It's usually just one time and it doesn't seem like gasping. I'll try and see if it's more prevalent after feeding, but I usually feed my fish right before bed time so I'll probably never know.

Sounds like it serves similar effects to human yawning, just in different ways. Very interesting info. +Rep for you

 

[thincat]

I think it's a sign of aggression. Me Bad!!! look how big my mouth is.LOL

 

[Innovator]

Thincat, you are on the right track "Yawning" cues often depend on the current activity of a particular fish, but commonly represent a display of a fishes dominance territorially and/or in performance for a mate. In terms of increased oxygen, it is also theorized that "yawning" would reduce oxygenation so I think both sides of that fence are, well...on the fence. I personally believe that there are respiratory and digestive reasoning, often seeing fish "yawn" under stressful circumstances and after a large meal. Another variable would be the stretching of their jaw muscles, taking into consideration that food intake is a primary function utilizing just their jaws alone in order to consume food without chewing.

 

[Crepe]

African cichlids do the same thing.

 

[Kurt_Nelson]

Funny... before I read very far, the thought going through my head was, "I wonder if he's talking about Bangaii's..." Yup, you were.

I've noticed the same thing with my Bangaii, and from what I've seen and read, I think like thincat and Innovator mentioned, it's a type of "bluff" - it's showing you who is top dog. My Bangaii will do it, often accompanied with that clicking/thumping noise they make. Hard to describe, but I'm guessing you've heard it since you have Bangaiis.

 

[AdamHorton]

I actually haven't heard the noise you're talking about. Maybe I should look (or listen) a little closer...

The one that I remember seeing was a male, and he was part of the pair that usually mate (in fact he's holding eggs right now). I don't know which of the mated pair really wears the pants, but I thought to myself that he could be stretching his jaw, so that makes sense.

As far as the damsels go, a display of intimidation would certainly go along with what I've seen.

 

[rush]

My antheas would do the same thing. It looks like they are yawning, but in fact they are just getting more oxygen, normally after they eat.

 

[atte]

I've never seen my Banggai do it but my chromis "yawns" quite often. I'll have to pay closer attention next time.

 

[mudraker]

My adult JDs do it too. It's really impressive and a little scarry looking.

 

[Greenmaster]

I know that Banggai Cardinal's are mouth brooders that might have something to do with the Banggai doing it.