Crystal bacteria jointly developed by SISO and South China Argriculture University Technology: a composite strain composed of water-purifying bacteria and nitrifying bacteria, which are used in the aquarium fish tank water purification system and the establishment of a nitrification system; main functions: 1. Establish a nitrification system, The water establish nitrobacterias system. 2. Remove heavy metals and chlorine dioxide to make the water quality cleaner. 3. When the new tank is filled with water, the algae spores can be "eaten up", which can inhibit the existence and growth of algae. 4. Clear water bacteria can remove "yellow water" and make the water quality more clear. 5. Probiotics can enhance the intestinal immunity of fish.