The fish tail will wiggle when the water is flowing, can creat a vivid sea environment for your fish tank. Used widely in the aquarium or fish tank, is a ideal ornament. Notice: These plastic fishes can ONLY float in the aquarium of fish tank with flowing water. You may need a air pump in aquarium, here is not included. California Proposition 65 Warning: This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.