Waterlife Paragon Improves fish health. Oxygen Tonic 200g TubImproves fish health Oxygen tonic.Paragon releases monotmoic oxygen in safe amounts. Assists in the break down of fish waste and plant debris, improving aquarium conditions. Dissolved, Paragon is even safe with delicate species - even urchins, starfish and crustaceans. Suitable for seawater, tropical freshwater, cold water aquaria and ponds.200gm / treats up to 2500 litres