A peace lily in a vase provides an aquarium for a beta fish. Beta fish, which are also known as Chinese or Siamese fighting fish, are so fierce that you can put only one in an aquarium or it will kill the other fish. But they're perfect for this aquarium, where the fish lives alone and where the plant thrives. It will help hold the plants upright, and because it's clear it won't mess up the look of the aquarium.
Soap kills aquarium fish.
Wash the dust from a fresh package of aquarium gravel and pour it two or three inches deep in the bottom of the vase. Treat enough water to fill the vase with chlorine treatment, available at a pet-supply store. Make sure to follow the manufacturer's instructions. Add the treated water and the fish to the vase. Insert the collar with the peace lilies into the neck of the vase, tucking the roots into the water.