Although Superclean is biodegradable and not harmful to people or animals if it is directly sprayed into e.g. fish tanks or ponds where there are fish residing, it may be harmful to the aquatic life. It can however be used to clean aquariums and ponds whilst empty, providing they are rinsed thoroughly with clean water, prior to the re-introduction of the fish. When used for cleaning sinks, toilets etc. that involves rinsing with water that goes down the drains.  Here it will be diluted greatly with the rinsing water and water in the drainage systems, so will not be harmful to any aquatic life when it eventually reaches it.