[header] How to clean trout for cooking [title] Insert the tip of your knife into the exit hole. [step] Hold the trout by its dorsal edge and turn it over to expose the belly. You'll find the exit hole near the tail end of the fish just under the lower fins. 
Point the blade toward the head, then slide it in smoothly. [substeps] To dress a fish quickly and efficiently, it's important to use a sharp filleting knife that offers a little flexibility.