Praziquantel is used widely to treat against flatworms such at gill flukes (Dactylogyrus) and skin flukes (Gyrodactylus). It can be used in-feed or in-water, depending on what you’re treating and the circumstances. But it’s notoriously difficult to dissolve in water.
If you’re treating the water, how do you dissolve this product? You could use a handheld blender perhaps? But that’s messy. I normally mix mine in a fish bag with water. And what else can you use to help dissolve the insoluble water? Did you know that you can use solvents such as ethanol and even formalin?
For oral medication, the powder is mixed dry with fish food, and then bound with some fish oil. On tuna farms, praziquantel is dissolved in propylene glycol and then injected into feed. The food is then frozen and fed out as needed.