Chase Cominski and Jake Runyan -- both locals -- were apparently caught stuffing their walleye with weights and other debris ... with things coming to a head on Friday as their fish were being weighed, and then cut open to expose the truth on Lake Erie.

As you can see, tourney officials started pulling out these little metal balls from the insides of the fish that Cominski and Runyan had up for consideration -- some are saying they're made of lead, but in any case ... they seem to have been jammed in for extra poundage.

There are also slices of what some claim are fish fillets -- in other words, these guys are alleged to have cut pieces of other fish and stuffed them inside as well, clandestinely.

Some outlets are reporting that these two fellas were actually the frontrunners of this tournament -- dubbed the Lake Erie Walleye Trail in Cleveland's Gordon Park -- but that obviously came to a screeching halt when everyone caught wind of what had happened.

You can hear the utter outrage from people on the ground ... they were screaming at these guys, demanding answers and even threatening to call the police. Runyan was asked on camera if he had anything to say for himself -- but he stayed silent and just looked on.

There are reports of the fisherman going on to win other contests in and around the area -- and now, all of the accolades (and prize money) they've racked up are coming into question.

The official event page on FB had a harsh statement, calling out these gentlemen as straight-up cheaters. They write, "Disgusted guys and gals, I’m sorry for letting you down for so long and I’m glad I caught cheating taking place in YOUR LEWT at the same time."