In a large zipper-topped plastic bag, combine bread crumbs and cheese.

In a pie pan or on a dinner plate, blend the mustard into the melted butter.

Dip the fish, one fillet at a time, into the butter mixture, coating all sides, then place each piece in the bag of crumbs; seal the bag and gently shake to coat.

Heat a large non-stick skillet over medium heat.

When hot, add the fish fillets and brown for 8 to 10 minutes per side, or until golden and fish flakes easily when tested with a fork (don’t let the pieces touch so they crisp nicely).