It is better to raise koi in bare jar. This kind of fish has a large size and a large appetite. It can eat and pull, so it excretes more. If the fish tank is covered with bottom sand, the fish excrement will fall into the bottom sand, which is not easy to clean up, and will pollute the water environment and lead to the deterioration of water quality. The bare cylinder has no troubles in this respect, so it is only necessary to clean it up when changing water, but the overall ornamental value will be worse.

1. Ceramsite: Ceramsite is one of the common bottom sands, which has no nutrients, but it can better cultivate nitrifying bacteria and make them adhere to it. Generally, if you raise small tropical fish, it is very good to spread it on the bottom of the tank, and some large and medium-sized fish can also be used, which is also helpful to maintain water quality.

2, aquatic plant mud: If it is a grass tank, it is most suitable to use aquatic plant mud, because aquatic plants can be planted on it, and ordinary fish tanks can also use it. However, it should be noted that the aquatic grass mud will be pulverized after being used for a long time, so it must be turned over at this time, otherwise it will be detrimental to the fish.

3. Tropical rain forest sand: Tropical rain forest sand is generally used as the bottom sand for raising South American aquarium, such as snapper, rat fish, etc. This sand is generally red and relatively small, so feces will not leak down, which is convenient for cleaning.