This worked well for me, I got the treatment schedule from Roy.
Stock solution ivermectin obtained from vet: 1 mg/ml. store in fridge,
protected from light. (brown bottle, box, aluminum foil, etc).
Make a dilute solution (user solution) at a 1/19 dilution (ie: 1 drop
ivermectin stock solution in 19 drops of water; 2 in 38, etc), keep in
fridge protected from light.
Use the DILUTED solution in the aquarium over 4 days at following dose (
I added the ivermectin when the lights were off in the morning)
day 1: 1 drop of diluted solution for each 10 gal aquarium water (~40 l)
day 2: 2 drops of diluted solution for each 10 gal
day 3: 2 drops for each 10 gal
day 4: 2 drops for each 10 gal
day 5: do a water change (~20-40%) and rinse filters.
NOTE: I had no fish losses with this regimen. all my fish (adult
angelfish and rainbows) looked good, ate heartily and lost the worms.
I later introduced another angel fish from the same breeder which turned
out later to also have worms and redid the regimen without any problems.
That was January. No problems since.
IF your fish look like they are under stress, then do an immediate water
change.
IF the worms are still present then redo the regimen, perhaps a week
later.
Good luck & happy fish keeping,
Dianne