The moon phases affect the height of the tides. High tides increase turbidity and make it difficult to fish. The best time to fish is when the moon is in the first and last quarter, so the tides are low. During new moon and full moon the tides are high, and it is not considered a good time to fish.

The moon causes tides due to its gravitational pull. The highest tides are seen during full moon and new moon and are called spring tides. The lowest, or neap, tides occur during the first and last quarters of the moon. Low tides keep the water almost clear, so the fish can feed easily. However, according to a survey of 200 fishermen reported in the "Big Book of Bass," bass fishing is best around the full and first quarter of the moon and the last quarter was the worst time to fish for bass.

A number of fish species also spawn during certain lunar phases. These fish usually reproduce in shallow water and are affected by the tides. Fisherman need a good understanding of the tides, which change four times each day. However, while knowledge of moon phases and tides can ensure a successful catch, sudden changes in weather can upset even the best laid plans.