Prazi-Power Praziquantel Powder does not stress your pond fish or damage filter biologics, an excellent treatment for internal worms in goldfish and koi. One or Two treatments of Prazi-Power and no water changes. Note: We suggest treating every spring to get your pond fish off to a great year and every fall before you put your fish to sleep for the winter. 10g per 1000 Gallons or 1/4 tsp per 40 gallons. Can also be mixed with food. Flukes are a very common initial cause of ulcers and open wounds which can lead to internal and external bacterial infections! Prazi-Power Praziquantel Powder works by paralyzing the parasite and allowing the fish and koi to shed the parasite.