The regulations say regarding snagging "Snagging of unprotected nongame fish species is permitted". Would "dip netting" be able to be classified as permitted for these types of fish? I have noticed that someone has illegally placed Coy/carp into places where they should not be and would like to help eliminate the fish from the area they are not supposed to be through "snagging" them per se with a net (not hooking them first)
Reading your question, I can tell your intentions are good, but, Idaho rules spell-out a specific exemption for "snagging nongame fish." Because use of a dip net for taking of nongame fish is not mentioned in the rules, it is not a legal method of take.
Contact the Manager in the region of the state that you live. They may have other "tools" or ways to deal with nongame fish that would help our fish management programs.