The smallest photosynthetic autotroph on the earth is Prochlorococcus. Photosynthetic autotrophs, photosynthesis is a biochemical process in which plants, algae and some bacteria use chlorophyll to convert carbon dioxide and water into organic matter and release oxygen under the irradiation of visible light.

Chlorella. It is an algae belonging to Cladosporium of Cladosporiaceae. Perennial submerged plants. Algae are filamentous aggregates, mostly forming loose spherical or irregular green clumps, with a diameter of 1-30cm, floating at the bottom of the water. Chlorococcus likes bright places without direct sunlight, likes warmth and avoiding heat, and grows well in the temperature range of 20-28℃, and the wintering temperature should not be lower than 4℃.

After leaving the aquarium and entering the natural waters, Chlorella can grow later. When it is suitable for aquatic habitat conditions, it will multiply and its population advantage will be outstanding. In severe cases, it will change the ecological environment of the water area and interfere with the species diversity of the water area.