Fish Safe: Made of premium resin and plastic, durable, non-toxic and pollution-free. Absolutely safe for fish. Have fun in the aquarium: when the diver floats, the treasure chest opens and closes to reveal the treasure inside, more vivid and active . SAFE FOR FRESHWATER AND SALTWATER - Ideal for various aquariums and safe for both freshwater and saltwater, either your freshwater or saltwater fish can play with their new thing. Unique design, bright colors, realistic image, suitable for aquariums. It is an important instrument to successfully maintain aquatic fish for the process of breathing. Increase oxygen levels, reduce CO2 and increase pH.