If you're asking the police to get involved in a private matter over people that willingly entered a tournament...where does it stop? What law was broken? They put weights in fish. If you enter a 50/50 do you know who is drawing the ticket? There could be swindling going on. You willingly gave your $. Nothing was stolen.
Its little things like this that gives the state and government implied power. It is a private tourney, deal with it accordingly. The last thing we need in this country is more laws, regulations, and government involvement. Its like crying to your parents as a child when your sibling steals a toy. The police would only get involved if it became violent. Man up and deal with it. No need for anything further.