A common mistake anglers around the world make is to use the wrong hook. In North America this means using a treble hook to fish for carp. They are cruel to the fish as foul hooking is common causing scarring and other injuries. More important is the fact that treble hooks are very large and will spook wary fish. Treble hooks have narrow gapes and their geometry is such that a good hookup is not always assured.
Most trebles are of dubious quality and they have a tendency to snag on weeds, etc.
The best size range is from 10 to 2, depending on what you are trying to achieve with your rigs. Baits Carp will eat anything. I have reports of carp eating live shad on trot lines, crawfish, hot dogs, worms, corn, maggots, spam and breakfast food. Links to other Carp Sites Books on Carp Fishing .