I don't soak their food but instead add it directly to the tank. For my 75 gallon tank I would take 6 to 8 nice-sized cloves of garlic, crush them as flat as humanly possible and then mince the flattened garlic. The goal is to try to do as much cellular damage to the garlic as possible. I scrape it all together and add it to half a cup or so of tank water and let it steep for 15 - 20 minutes. Allicin, the important component of garlic, is very short-lived so don't skip out and buy any store preparations of garlic.
Also, don't let it sit for more than an hour or so. Pour the tank water through a small mesh strainer (or you can just strain the garlic out by hand) into your tank. I like to press out all the liquid of the soaked garlic too. Any bits and pieces that get into your tank are likely to be eaten by your tang, which is a good thing. I know it may be hard, but try to pour the garlic water on or near the affected fish. You should notice less cysts on your fish. You can repeat this for a few days. The only time I ever overdosed a tank was a 20 gallon tank with a very deep sandbed that had little gobies in it. I bet there wasn't 10 gallons of water in it between the sand and live rock taking up so much space. I added about 6 cloves' worth of garlic to that little tank that already didn't have much filtration on it and it nuked some of the gobies. On my 75 gallon tank, I've added as much as an entire pod of garlic to it without any ill effects on my fish, inverts, anemones, or corals. They might look ticked off for awhile but they'll get over it. Don't worry if the garlic temporarily gives a slight haze to the water. It will all filter out later in the day.
Hope that helps! I saved a horribly infected purple tang from certain death with garlic, and since then have used it several other times too, all successfully.
~ Sherri
