During the rain, the fish are feeding aggressively. Moderate rain contributes to the presence of more insects along the water, and more organic material is introduced into the water body. This encourages fish to start eating more actively.
The sound of raindrops on the water surface changes the daily routine of fish, especially this is visible in the shallows with standing shallow water. Some people think that fish hide somewhere during the rain, but we do not think that is the case. Fish only change the “behaviour”; some are moving to the surface, others are more aggressive, etc. The change is good for fishermen who can adapt. Especially this applies to those who fish pikes and carps.
When fly fishing, we can use larger artificial flies, even dry flies. If the water level rises fairly quickly, the fish will move to the banks of the rivers, otherwise, they will be in usual places. If the water rises quickly, it is a sign of fishing with large nymphs and streamers. Then the biggest trout comes out, so it’s worthwhile to make an effort.
In the case of carp fishing, there are no major changes, except that the water is refreshed and the fish can breathe more easily. If, however, the rainfall is really huge and the water cools greatly, their metabolism will slow down and fishing will be worse. And even then it’s better to go fishing than go work or just sit at home.