What is "melafix"

Melafix (a proprietary name) is an all-natural aquarium antibiotic consisting of an essential oil of the Melaleuca genus. Contrary to popular opinion it is not made from the common Tea tree, Melaleuca alternifolia, but from Melaleuca leucadendra, also known as the Cajeput Tree. This is confirmed by the manufacturer's Safety Data Sheet.

It is a wide-range antibiotic product, and thus is effective for a wide variety of mild gram positive bacterial infections, such as fin rot. However, it is generally ineffective against aquatic parasites and is typically used for treating the wounds caused by them in order to prevent secondary infection by other microorganisms.