I dealt with it Before, and the best thing to get is Levamisole HCL (its a Pig wormer) anyways i try the Fembendazole on food and it doesn't work as good,
here is what a member of my local club post on how to convert.
Convert your Gallons to liters
3.786 X Gallons = Liters
Liters x .0025 = Levamasole G (2.5 ppm)
Liters x .005 = g (5.0 ppm)
After i treated my cichlids 24hrs later i did a BIG Water Change in my 125gal about 90% of water went out i left enough for them to swim/breath.
here is the link to the whole complete thread if you would like to read it.http://aquacharlotte.org/CAASBBS/viewtopic.php?t=5728
i hope this helps.