What line is used to catch small fish?

Generally, the main line of 0.8~0.6 and the secondary line of 0.6~0.4 can be used to catch small crucian carp. However, in the end, we should consider where to fish. If it is wild fishing, it doesn't matter, because wild fish have better physical strength and are all raw, as long as they are not too thick (generally I use the main line of 1.0). If it is a competition or a black pit, you should also consider the pit. If you want to steal a donkey (fish released the day before or a few days ago), try to use a smaller pole and a thinner line. However, there are many specific factors to be considered, such as: fish species (crucian carp or carp, if it is carp, the line group will be thicker than crucian carp, and personally think that the line group for carp fishing is only 2.0), water quality, weather, season, bait (some can use red worms or vegetarian bait) and so on. I hope I can help you. You can continue to ask questions if you have any questions.