Then quit. Or stop trying to sell your stuff on a public forum. While I agree it is B.S. to ape someone elses paint jobs, it is an inevitable fact of life when you post on a public forum with millions of users. I am a member of several groups on Farcebook and honestly, from what I have seen, the cream rises to the top as far a what sells and for how much on the auction pages. If people are truly copying your patterns and they are truly unique, you are free to use the "implied copyright" part of the law and hire a lawyer to send out cease and desit letters to everyone.
Personally, if I notice someone posting a bait that was obviously inspired by my pattern, I take as a compliment and move on. The so-called "custom tackle" business has never been much of one, and the number of folks actually making a living at it is small, very small. So my advice is, paint for the joy of it, sell some if you can, and don't be all butt hurt. After all, I am sure that you, like everyone, started of copying someone else's work until you gained the skills and confidence necessary to become creative and produce your own.