Bill's Guide

Fish the Solunar Cyle

Solunar Theory shows that the sun and moon influence how fish feed. Master their celestial movements to help you catch more!

by Bill Bernhardt

Most avid anglers are well aware that the best time to go fishing is when fish are feeding and that tends to be at both sunrise and sunset due to lower ambient light levels. However, there are also two other periods during the day when fishing can dramatically improve and those times coincide with both the rising and setting of the Moon.

In fact, fish are most active during the 45 minute period preceding and following these four events. By choosing to be on the water at times when the sunrise and sunset, along with the moonrise and moonset, coincide with either new or full moon phases, you will find that your odds of catching fish dramatically improve!

The Theory

The idea that the position of the Sun along with the phase and position of the Moon can drastically affect the quality of the fishing is commonly known as Solunar Theory and, while many fishermen disparage this theory, scientific experimentation has proven that there is significant evidence to support it. Therefore, below you will find a detailed explanation of Solunar Theory so that you too can drastically improve your catch rate when planning your fishing excursions.

But first, a bit of history.

The Origin of the Theory

In 1926, a gentleman named John Alden Knight, who was an avid fishermen living in Florida at the time, noted that there were days when the fishing seemed to be significantly better than it was on other days as well as at certain times on certain days. This observation lead him to wonder what the cause of this disparity was and thus, he also began to observe weather factors as well as other environmental parameters in an attempt to determine the cause so that he could accurately predict on which days fishing would be most productive.

He began to discuss both his intent and his observations with his neighbors who were also avid fishermen as well as with commercial fishermen. These discussions set him on a course to develop his new “Solunar Theory,”named from the root words "Sol" which refers to the Sun and, "Lunar" which refers to the Moon; thus the name "Solunar." 

Because Knight was a naturalist, he approached the problem scientifically. He compiled a list of 33 factors which, according to the folklore he had obtained from older fishermen in his locale, either influenced or controlled the day-to-day behavior of both freshwater and saltwater fish. Then he began a systematic exploration of each factor.

Knight determined that out of the original 33 factors, only three (Sun, Moon, and Tides) seemed to have any real merit. However, he also reasoned that because the cycle of the Sun was the same each day and yet, the observed periods of peak fish activity seemed to occur at different times during the day and/or night, that neither the ambient light from the Sun nor the Moon could account for the observed peaks in fish behavior. Furthermore, there could obviously be no tidal movement in creeks or streams and thus, he also reasoned that tides could not possibly have any effect on freshwater fish living upriver well above the influence of the daily tidal flow.

Yet, the folklore that he had collected was firmly based upon observations made by his fellow fishermen over an extensive period of years and thus, he felt that it must have at least some merit which led him to wonder if perhaps if it was the movement of these celestial bodies that was affecting fish behavior instead? Therefore, when conducting his initial research, Knight only took in to account the times of moonrise and moonset but, his research revealed that there were two additional peaks in fish activity that occurred in between moonrise and moonset. Therefore, he classified the two more evident periods as "major" periods and two less evident periods as "minor" periods.  

Ultimately, based on both his observations and his research, in 1936 Knight created and published a set of "Solunar Tables" that enabled anglers to accurately calculate these peak periods of fish activity by taking into account the geographic location (East or West) of a base point (Time Zone), and then adjusting for Daylight Savings Time when appropriate. Therefore, because the Moon seems to be the controlling body due to its close proximity to the Earth, using Knight's Solunar Tables, a fisherman can determine when the Moon is directly underfoot or overhead at their particular location. Thus, it should be noted that fish are most active during periods when there is a full Moon or a new Moon and they are least active when there is a quarter Moon and a three quarter Moon due to the fact that the Moon and the Sun's gravitational forces are strongest when in line directly above or directly below a given location.

Solunar Peaks

Peak Times

Therefore, according to Solunar Theory, whenever one of the aforementioned Major or Minor periods falls within 30 minutes to one hour of sunrise or sunset, you can expect a significant increase in fish feeding activity. Also, whenever you have a moonrise or a moonset during that same period, the fish’s feeding activity will be even more furious. Finally, whenever, these periods occur during either a new Moon or a full Moon, you can expect the greatest amount of feeding activity of the entire season.

Peak Days

Fortunately, thanks to modern astrophysics as well as the work done by John Knight, we now know that both the Sun and the Moon are the two major sources of celestial influence that affect our daily lives. Therefore, the closer to your location that either of these two celestial bodies are at any given time, the stronger their gravitational force is. In addition, we also we know that because the Moon is closer to the Earth than the Sun is, the day the full moon appears is the day of strongest influence during the course of each month.

Peak Months

During a full Moon, the Sun and the Moon are positioned nearly opposite of each other in their orbits with the Earth in the center and very few minutes pass without one or the other being in our skies overhead but, during a new moon, both bodies are in near perfect synchronization and consequently, they travel the skies in unison; thus combining their forces.

But, because of the interaction between the numerous Solar and Lunar Cycles, no two days, months, or years are the same. However, it should be noted that the month of June always has more periods of combined Sun and Moon influence than any other month.  

Scientific Support

However, because there are so many different myths that attempt to explain the reason for these observed months, days, and hours of peak fish feeding activity, an experiment to evaluate Solunar Theory was conducted at Northwestern University in Chicago, Ill. by biologist Dr. Frank A. Brown on oysters that he had flown to his laboratory.

Of course, the reason that Dr. Brown chose to use oysters for his experiment is that oysters are filter feeders and thus, they open their shells with each high tide. Therefore, Dr. Brown wanted to see if this regular feeding cycle was due to the change in water levels or to an unseen force generated by the Moon’s gravitational force. He placed the oysters in a saltwater aquarium and isolated from them from sunlight.​

Dr. Brown observed that the oysters continued to open and close their shells according to the schedule of high and low tides in the location where they were collected despite no change in water level in the aquarium! But, by the second week, the oysters had apparently adjusted their feeding cycle to match that of the times when the Moon was either directly overhead or directly underfoot in Dr. Brown’s location and thus, they adjusted their feeding cycles to match the tidal phases in his location even though they were living in an aquarium rather than in the ocean!

Therefore, Dr. Brown concluded that the oysters in his aquarium were indeed responding to an unseen force that corresponded with the movement of the Moon and not to rising or falling water levels.

Consequently, Solunar Theory is now widely accepted as an accurate method of predicting periods of peak fishing activity and thus, Solunar Tables are widely available both in print format and on the Web. Therefore, wise fishermen make good use of this invaluable tool to plan their fishing trips during times of peak fish feeding activity in order to maximize their catch rate because it apparently truly does work and, of course, the universal goal of all fishermen is to catch more fish.