Given the size of the tank and the animals in question, I am not convinced this is brooklynella unless you are seeing symtoms beyond the sores such as excess body muchus or other relative indications. Laboured breathing, loss of appetite or lethargy. The aggression of these fish in such a small tank would cause fighting that could result in lesions, fungal infections and possibley bacterial problems.
What I would suggest for now is each fish be treated in it's own <<quarantine tank
>> (or at the very least separate the clowns) with Nitrofurazone
to aid in any problem that has arisen from fighting. If the fish are infected with brooklynella they can then also be treated as indicated by TerryB above.
When treatment is done, please be sure these fish are not
returned to the same habitat. They are not compatible in such a small space. If you are wanting 2 fish for the 13 gal
, I would suggest two ocellaris. The tomato clown and damsel could be housed together in a different much larger tank.
When using garlic extract, it is best to soak the foods in it rather than just adding it generally to the tank. When ingested, the properties of the allicin will have a much better affect. One drop should be plenty for the amount of food needed for 3 fish and only 1-2 times a week. Too much and you can foul the water quality.