Circle Hooks are self hooking no need to strike and a very high % rate of lipped hooked fish as apposed to J hooks which cause a lot more damage to fish lips and internally more gut hooked fish than Circle hooks. Primarily used for commercial long liners at sea, one big advantage was that they did not catch as many % of unwanted quarry like sea turtles and sharks only the fish they were after and the major thing was they were lipped hooked as apposed to gut hooked J hooks and unwanted quarry kills. Circle hooks are mainly barbed with the point turned in, some advantage the point don’t get blunted, they do come barbless now and in smaller sizes. Just wonder if you would use these for Carp Fishing or have used them.
I can’t really comment on the hooks as such because i would never use anything over a size 14 and barbless in my fishing, i pole fish so i need to keep things in the right size, as for the so called ”parrot mouth” and what causes it, well many say it is Barbless hooks, some say it is more like Barbed, then you get some saying it is Braided lines but others say it is low diameter lines, do we really know what causes these problems?…for a long time now i have thought it more to be the way some play the fish, cranking like mad instead of playing the Carp does it untold damage, remember one force pulling one way the other pulling the other way, what is going to go?…the line, no because we are told we need to use line that can hold up so it has to be the lips, this is the weaker point, just imagine having a hook in you’re mouth then running away only to have it stopped dead, what would happen, one thing is for sure you’re lip would be a mess and this is what happens to the fish, chunks are taken out of the mouths simply because they are not played in the right way, so the hook pulled, did it?..or did it rip through the lip because you played it all wrong, we have to look at this from all angles and this is my take on this matter.