Silver carp and bighead carp are cultured in fish ponds without feeding. Because this kind of fish is filter feeding, it can eat plankton in water, even if it is not fed. Usually, fish culture in fish ponds is mostly intercropping, that is, many kinds of fish are raised in the same pond, but these fish must be distributed in different water layers. For example, silver carp is the upper fish, grass carp is the middle and lower fish, carp and crucian carp are the bottom fish, so they can be intercropped.

1. Silver carp: Silver carp is one of the four major fishes. As a filter-feeding fish, it generally lives in the upper layer of water and can eat plankton, which can improve water quality. This kind of fish is lively and likes to jump, but it is not very agile and its own courage is very small.

2. Grass carp: Grass carp is also among the four major fishes. It lives in the middle and lower layers of water, and usually feeds on plants. There are not enough aquatic plants in the fish tank, and it can also be fed with some green fodder such as pasture. Its feces have certain nutrients, which can promote the growth and reproduction of plankton, thus providing feed for silver carp.

3. Crucian carp: Crucian carp is a bottom fish. As an omnivorous fish, it can eat a lot of things. It grows fast and is not easy to get sick, so it is a very good choice, and it will not interfere with the upper silver carp and the middle and lower grass carp.