I haven’t used it but a dealer I knew years ago used it to treat and seal any wounds on is fish he swore by it as it gave a good seal all he did was clean the area apply the tea tree oil and that was it and he got great results
4000 gallons queni koi drum to jbr plastics bio chamber with 75 litres oase hel x media on bottom drain skimmer line also into drum 55 watt submersible uv 240 litres air and 12 fish
A koi dealer who I have a lot of respect told me many years ago to use 100% pure Tea Tree Oil as a first stage wound cleanser (applied with either cotton wool buds or a lint style gauze held in tweezers) before applying anti bactericide and the final wound sealant, (usually propolis).
His view was that TTO was far less severe than either hydrogen peroxide or Roccal as the first stage wound cleaner but was very effective nonetheless.
I have used it ever since for that purpose = I get mine from flea-bay!!
4400 Gals; gravity fed Nexus 300 to EA 55W UV (fed by dry mounted Messner 13000) and Bakki Shower (4 tray) directly pump fed (20,000 l/hr) from the pond; independent skimmer line which is fed by a dry mounted pump through a small sand filter, Airtec 130, unheated.