Ok, I have two green spotted puffer. I know that these fish are better in brackish water but they were in Freshwater at my LFS. I have them since about 2 weeks and they don't seem to be really healthy. They rub theirself against gravel and rock and the seem to bend their body in 2 from time to time. The smaller one seem to be sicker because sometime it stop swimming and stay between two rock or on the gravel like a dead fish. The bigger one do that sometime but far less than the smaller one. Since they were rubbing theirself I tought they had somekind of parasite and my LSF recommended using a product called Parasick RIGA. It look alot like methylene blue to me. As soon as I added that thing to my tank, I noticed a bunch of really really small white worm swimming everywhere in the water. What are these and how can I get ride of them? Most of them got sucked up by the filter but alot of them are still free in my tank. Thanks alot for the help