There is a lot of misinformation online about what garlic can or cannot do for fish health. It is not a miracle cure for ich by any means, and is never a substitute for a proper QT regimen. I brought home a 4" blue hippo tang today which has been eating our LRS Probiotic Herbivore Frenzy for a week at the store. I still intend to QT and observe the tang before introducing it to my established reef tank. Many people will see their fish get a few spots of ich, then start feeding garlic soaked nori for 3-4 days and when the spots disappear they believe the garlic "cured" the ich. The reality is that is simply the natural progression of the parasite's lifecycle. The parasite feeds on the host, then drops off into the substrate to reproduce, where it shields itself in a cyst if you will before "hatching" out free swimming tomites to seek out new hosts several days later.
We had enough emails about garlic that we added a section to our website addressing its use in food.
The following is a direct quote from the FAQ page of my website:
Q: How Much Garlic Is In Your Foods?
A: Great question. The inclusion of garlic in saltwater fish food has proponents for and against its use. A large segment of the reef keeping community believes Allium, the active ingredient in garlic, has anti-parasitic and immunity boosting qualities. While many reports of its effectiveness are anecdotal, a whole lot of hobbyists and store owners are convinced adding garlic "works."
Our informal testing revealed that adding garlic does in fact cause fish to come inspect the food rapidly, possibly simply to investigate the pungent aroma. Sometimes getting fish to find and ingest ANY food is half the battle, especially with a new purchase. (Many store owners reported 65% less fish losses in 2013 since using our foods to feed new arrivals.) Surveying the available foods on the market today reveals that over 85% have garlic listed on the label.
Studies were recently discussed on popular web forums which suggested long term use of garlic could have a negative effect of fish health. Please recognize these studies used a ratio of "garlic per gram of body weight" far in excess of what we ever add to our foods. Our food processing method NEVER permits any actual garlic "meat" to get into the food or ingested by your fish. When we make a 100 pound batch of Frenzy Food, we merely add a few ounces of strained RO water which has some minced garlic in the container. The water is "flavored" if you will, but no cloves of garlic are minced and added to the blend. We have many customers feeding our foods every single day for almost two years with no ill effects reported. We feel the feeding response generated by adding a little garlic flavored water offsets any possible negatives.