Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
a) Is it REALLY fungus? Compare to Columnaris, a bacterial problem.
If it is Columnaris:
It can spread FAST, and kill FAST. There are several varieties. Antibiotics that target Gram negative bacteria will treat it.
Other bacterial problems might show up as red streaks near the injury (it got infected and needs stronger meds).
b) REAL fungi usually attack already compromised tissue, such as an injury or infection. The first line of defense is to cure the original problem. Sounds like this could be what is going on, if there is fluff growing where the fish got scratched.
c) A clear scrape, no fuzz, might just be the tissue showing where the scales got scraped off, and needs no treatment except clean water.
Water changes to remove as much organic matter from the water, especially at the bottom of the tank, and in the filter.
If the problem is JUST diagnosed, then something simple like Melafix and Pimafix may help (Not for Anabantoids, though). If the problem has gone on long enough to be internal these will not work.
A small dose of salt may help fish under stress. 1 tsp per 10 gallons max for most fish, plants.
Moving a single fish to a quarantine tank can help- minimize the spread, reduce the cost of treating, maintain a bare bottom for more effective treatment and cleanliness.