Getting back to immunity and diseases we can save a lot of money by buying sick fish. I do it all the time. I recently bought a copperband butterfly for five bucks that was covered in parasites. many of the rest of them in the tank already died and the store owner knew the rest would not last the night. If I had room, I would have taken all of them. I put that fish in a small tank with copper/formalin and quinicrine hydrochloride and added a diatom filter. (I think I may have invented that combination of drugs many years ago) That combination of drugs will clear a fish of "visable" parasites in a day. The diatom filter will prevent "most" but not all of the parasites from re-infecting the fish. In a few days that $5.00 copperband was as good as new and I put it in my reef. My older copperband was not amused so I was able to catch the little guy, let his ripped fins heal and I gave him away.
If a fish is laying on the bottom, gasping, I would not buy it although it may be able to be saved. If I got the fish for free I would take it. I am surprised so much ink is wasted on parasites when they are so easy to kill. Even copper alone will work but if the fish is in really bad shape, it may not kill the parasites before the parasites kill the fish.
I realize people are saying "Yeah but velvet is worse than ich". Yes it is, (especially crushed velvet) but it is also cured the same way. All parasites are crustaceans and all crustaceans are killed with the combination of drugs I mentioned. The quinicrine is a malaria drug and malaria is a parasite. I probably took it every day when I was in Viet Nam. I am not sure if it was the exact drug, but I didn't get malaria and I was in the jungle the entire year, never coming out and I never saw a road, roof, wall or electricity that year. Just rain, and when
it wasn't raining, it was raining harder. Once a mosquito was chasing me and I could tell by the expression on his face that he wanted to bring me home and either feed me to his kids or mate with me. The only thing that saved me is that his "antlers" got stuck between two trees. Yes, that is how big he was, he had antlers.
I caught a scorpion once, actually I held it down with the butt of my M-16. I cut the top off of a beer can. (we sometimes had hot 3.2 beer which is more like warm, iodine lased water with almost no alcohol in it, we had to get it from the air force) His elbows were hanging over the top of the can (true story) He was not in a good mood and was looking at me with firey eyes that said, when I get out of here, you and your friends are history. I knew it too so I couldn't let him go. Someone (who was petrified of the thing) said to step on it. Like yeah. Our boots were good but not that good. I shot it with a my 45. The first shot just wounded him and made him madder. Then I shot him with my M-16, twice. The second shot did it, but he lived long enough to put a curse on me. To this day, I still look for scorpions under my bed.
This is actually where that scorpion incident took place. This was a clearing on the Cambodian border.
This is what that place looked like from the air. It was a scorpion paradise.
is it safe to feed earthworms to marine fish ? 
,more over what dosage u recommend.
