According to the flower encyclopedia, there is a layer of brown hanging on the wall of the fish tank, which I believe many fish farmers will encounter. Hang this brown thing on a white transparent glass fish tank, which greatly affects the appreciation. In fact, this is the most common brown algae in fish tanks. Some fish friends may not know that these brown algae grow on the wall of the fish tank. It shows that the water quality of the fish tank is broken and needs to be changed. Actually, it's not. On the contrary, if this brown algae appears in the newly opened fish tank. Then it just shows that the water quality of our fish tank is slowly entering a stable stage, which is a good thing. When a large number of brown algae appear, it means that the water body is too fat and needs to be treated at this time.