A while back I used the Jungle brand parasite tabs to try to deworm my green spotted puffer. I would put the frozen bloodworms in a cup, add tank water, drop in 1/4 of a tab, and let it infuse the food with the parasite treatment. That seemed to work well for me. Soaking their food would be better I think than just chucking the powder in their tank.
I will also say the other two times I tried to use the Jungle tabs the fish did not make it. Either due to there being a different disease, or the fish being too weak/too far gone for the treatment to have effect.