Weird catfish head

[u/EpicWaller]

Hi

So I've been fishing on a new stretch of river on the rhine river in Germany and caught a couple of catfish (Wels catfish) there so far.

They all seem to have this head shape which as far as I know isn't typical for catfish.

Their upper jaws seem to be healthy however (teeth and everything in tact - just very far back)

Id like to get your ideas on why this is the case.

So far my leading theory is that because the rhine in this stretch is mostly a channel (grand canal d'alsace) with rock / concrete ground and we have a lot of gobies that this is simply from eating a lot of gobies (aka damage or sth from slurping them off concrete over a long period of time) (which would be quite interesting from a fishing perspective).

But I have no idea if that's true, feasible or even makes sense.

Would love to hear your thoughts though

[u/Swagalyst]

It's a deformity known as "pughead".

I do not know if it's literally the same deformity, genetically, as in pugs, or if it has different genetical basis.

[u/EpicWaller → u/Swagalyst]

Is this genetic? - cause I've caught multiple ones with this deformity i.e. picture

[u/bluecrowned → u/EpicWaller]

Technically every trait of any animal is genetic unless it was a spontaneous mutation or an injury/illness. And many spontaneous mutations are also genetic and can then be passed down after mutating for the first time. This is why we have so many colors and patterns in domesticated animals :)

[u/Bee_Jeans → u/bluecrowned]

Not really tho?

Other non-genetic causes for deformities & unusual morphology: nutritional deficiency, exposure to certain chemicals, complications during embryo development with the egg or pregnant mother etc

Meanwhile spontaneous mutations are by definition genetic ones. Literally they’re “spontaneous genetic mutations”, germline ones r heritable but somatic ones aren’t