Mud? That seems really odd. I’ve eaten a lotta trout and never had one taste of mud.
It’s gotta be due to their living environment. All the ones I had were taken out of snow melt lakes and streams on the East flank of the Sierra Nevada, so sub-40F waters above 7,000ft elevation, and they were ALL excellent eating; not the vaguest hint of anything bitter or foul.
A light coat of corn meal inside and out with a hint of salt and then into the frying pan... I’m makin myself hungry, here... LOL!
Trouts not my favorite but clean them , scale them with a copper pad, wash them, place lemon pepper and butter in the body cavity, wrap in tin foil and cook over a charcoal grill on medium heat. That’s pretty good. Your way is good to. High mountain stream brookies that way with eggs, biscuits and hash browns in elk camp is not bad either. Elk loin butterfly cuts for breakfast the second day fried is not bad either. We head to camp already at near 5000 feet above sea level in the Rockies. Cold clear water is the key. We cuss snow sometimes but depend on it every year. Regards