After thinking about this and doing a bit of reading then considering the amount of hybrids about. I am beginning to wonder if any perfect pure DNA specimen of any fish actually exist just thinking about Carp, Goldfish, Commons, Koi, Mirrors, see what I mean.
With
Cyprinus carpio (king carp) commons, leathers, mirrors and Koi they are the same species Eg they are all king carp. In the main it's man that has brought about the physical differences by selective breeding of "freaks" for the want of a better word.
If such crosses with either goldfish or crucians is achieved, they would be unlikely to attain the weight to produce a record fish, as both species are much smaller. Ergo, the prodigy of such parents would be restricted by the smaller parent.
It's why hybrid bream never reach the size of true bream of record size.
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Alan one of the reason why yes. But to you and I clipping a bit of fin off we know what we want, But to the general angling public I can see them hacking half a fin away to send as a sample
Got to be honest here, when I've taken
a scale off a roach you wouldn't even know it had been removed. It's unnoticeable in the scale patterning and I've had to look hard to find where I've taken it from. There's something about roach of all species and the ease in which they shed scales that's a bit mystifying. Whether that's a predator defense mechanism or not I'm not sure
Removing a scale is also the accepted norm for the EA when age profiling all species.
Take your point about sufficient species separation, but given the amount of research in DNA and genetics on fish (its sexy and where the money's going) I've never come across such a problem being raised in any of the literature I've read.