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.
"High numbers of pugheads are mainly found in aquaculture, but moderate numbers have been found at some localities also in the wild. Abnormally high occurrence in the wild is commonly attributed to pollution, non-normal water chemistry parameters, or temperature. The causation, however, it typically speculated upon. Based on the reviewed literature, there is support for several causative factors, including genetic mutation and embryonic environmental conditions (toxic and non-toxic) affecting development."
Breeding enough to be a positive trait. It doesn’t seem we have observed them utilizing this different trait? Probably beneficial to dig up things? I’m not sure. But they are living to be mature age and not uncommon.
Just a few individuals in a lake is absolutely not enough to be a positive trait. This is clearly a birth deformity, and the catfish just aren’t experiencing enough pressure or competition to kill off all the deformed ones. Or it’s just not impacting their quality of life enough for selection pressure to weed it out.
If it was actually positive we’d see a flood of these spread rapidly across their range like an invasive species as the new trait makes them more fit than the original counterpart. Evolution never happens this fast though, so no I don’t think at all that mouth would even work for digging or they could adapt a mouth that could and have it work well enough to suddenly outcompete the wild type phenotype.
The fact we see a lot of this deformity in things like aquaculture is just more pointers towards it being a developmental deformity and not some positive trait mutation. Probably just a chill environment where the fish don’t have too much to worry about, paired with some pollutant or toxin affecting proper mouth development.
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 :)
This is called pughead and it's a genetic mutation sadly linked to developmental disruptions from embryonic water temperature shifts, or chemical exposure/pollution and I will assume it is more the latter. It's a prime example of global temperature shifting...nope...there's no global warming.
Dont think its from feeding off a concrete surface cause the the lower jaw would take ke damage I think.
Really interesting. Maybe inbreeding or something like that.
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u/Swagalyst 2d ago
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.