Phenoxyethanol is an oily liquid that is often used to treat fish fungi and promotes the healing of fins after an attack, for this reason it is sometimes used to aid healing of fins after damage from another fish etc. It is typically sold in a 1 or 2% solution and is often made into a concentration in the aquarium of 100 mg/L.
It can also be used as a fish sedative/anaesthetic but this sort of treatment should never be undertaken without the advice or aid of a veterinary surgeon.
Harmful if swallowed, inhaled or absorbed through the skin. Severe eye and skin irritant.