The Solunar calendar is based on the solunar theory created by John Alden Knight in 1926. This theory stays that the mutual positioning and influencing of the moon and the sun has an impact on the behaviour of fish and other animals. But the results of the calculations based on the solunar theory are not taken into consideration in our classic forecast. If you are a Premium member you can turn on this option in the app settings. The solunar calendar is applicable also on the fishes that are not supported directly by the app.