Water is among the five elements represented in Feng Shui: water, wood, fire, earth, and metal

Water fountains and fish aquariums are common choices to represent the water element requirement in Feng Shui design. Although the fish, Betta splendas, in a fish bowl is representative of the life force it is the movement of water that is the focus of placing a fish bowl somewhere in your environment. It is important that the water is maintained so that it is kept fresh and clean. Don't allow the water in your fish tank to become dirty or stagnant.

That is not good for your fish or for your environment.