In researching this topic, there are two evident paths that emerge. One is like obligatory folklore offered up for bodies of water that are not influenced by tides/waves. Discussions of moonsets, reproduction, and gravity all come into view without any meaningful scientific data.
If the fish are near coastal shorelines, then an air of certainty, of a causal connection, is offered up by fishermen, especially when discussing speckled trout. There the fishermen write with certainty that a few days before and after the full phase of the moon offer excellent fishing.
I can only offer up a personal experience of an excellent outing in B.C. While loitering out on a lake east of Merritt, B.C., my son and I casually made our way back toward the take out under full moon light. The slow pace was prompted by the stunning beauty of the full moon. And, as we slowly kicked trailing our flies the fishing picked up to a crazy pitch that was, well memorable. I recall trying to capture my son fighting an epic trout with the camera. I was shooting into bright moonlight off of the lake’s surface trying to get his silhouette. The fishing was adrenaline producing. We probably were violating the local reg’s, I am not sure. But, I have never forgotten, nor has my son, that amazing half hour or so of amazing fishing under a moonrise. So, coincidence or a connection?
So, the full moon phase is upon us. Perhaps some will benefit from that time of the month. Oh, and an aside…I dare you to fully read the study on the Moon and the Trout in the attached treatise (here)