Ich is a parasite. A critter that feeds on the fish and require fish to survive. If your tank has ich, it can be kept at bay by keeping the tank and it's livestock healthy, but there is always the potential for an outbreak. Garlic is supposedly an immune booster. I use it too. Feeding well and keeping a low stress environment is also key to keeping it at bay. Cleaner fish/shrimp can help remove pests from fish, but won't cure ich. Using UV may kill waterborne Ich that runs through the UV unit, but Ich isn't always in the water column. They are in the sand, and on the fish.
Ich has a lifecycle. You can theoretically rid a tank of ich by removing all fish from a tank system, placing them into quarantine, and leaving the tank fishless for a time period. The often suggested time period is often 10 weeks. Inverts are not affected by Ich and are not carriers. They can be left in the tank. I am no expert, but I think Ich's lifecycle is a matter of weeks. So the goal here is to remove the fish so the active ich starve. Then any dormant ich (eggs essentially) become active and also starve out. When the lifecycle takes it's course, the tank is hopefully ich free.
That isn't all unfortunately. The fish can carry ich and not show outward signs in quarantine. If they are healthy and strong, their immune systems can prevent a visible breakout. When they are put in QT they don't suddenly get cured. The fish can be treated for ich. Now this is where it can get quite tricky as not all fish tolerate all forms of ich treatment. There are two standard treatments for ich. One is copper (or cupramine). The other is with low salinity (hypo). Both methods have their risks and difficulties.
There are also a lot of other ich treatments out there. I don't know if they work. As for treatments, the best thing is to probably scour forums to see other's experiences. Then be as informed as possible and do what one thinks is best... and hope it works. Honestly I don't like dosing a new fish with cocktail of medicines. Especially if they look healthy and are happy. But I currently tend to take a few precautionary measures. So far I haven't run into ich, thankfully. But then again my tank is small and I only have 4 fish at the moment.
For any new fish I usually do the following: (my quarantine tank is cycled and always running, but some treatments can nuke that cycle.. it is a give or take.)
-Formalin dip (Formalin MS): After drip acclimation to the tank water in a container, I dip the fish in Formalin. The dip water has to be oxygenated very well, so I utilize an airstone. Formalin knocks O2 levels down, so caution is required. This blasts external protozoa/parasites/fungus. Observation is required. The bottle states <50 minutes, no more. Immediately end treatment if the fish appears stressed. I have treated clowns, blennies, and wrasse without incident. Formalin is formaldehyde, which is nasty stuff. Thankfully the treatment only uses a little bit. I doubt a dip will cure ich. But maybe it helps?
-The fish then goes into quarantine. Lights off, and quiet time for at least 24 hours. I observe for stress. I don't try feeding right away, unless the fish is out and about and without fear. For good measure I like to let the tank sit for another 5 days and just observe the fish. My QT is currently next to the display, so it can see the main tank and it's residents, and they can see it. I have no idea if that matters or not.
-Next I run a single course of Prazipro in quarantine, which takes about 5 days. This treats for internal parasites/worms. Not for ich. Good stuff and doesn't bug the fish a bit. If the fish shows signs of internal parasites (stringy poop), I may do a second treatment for another 5 days.
-I try to QT for at least 4 weeks total. After the prazi, I just observe and don't treat for anything else. Some people will treat with cupramine by default. I haven't. But I have thought about it.
Good to know too... do not use Prazipro and cupramine together. I hear it is a very bad mix. I 'think' prazipro and hyposalinity do work together. I never tried hypo however. Best to read up if you are thinking about it.
