O.S.T. stands for Osmotic Shock Therapy which is commonly referred to in the hobby as hyposalinity [water that is deficient in sea salt]. Essentially, O.S.T. simply places the infectors [Cryptocaryon parasite---ick] in an environment in which they cannot survive while the host, (or infected fish) can. This remedy WILL NOT work in reef systems or invert tanks as it incorporates lowering the specific gravity of the entire system [hospital tank] to 1.009.
To drop the salinity, this is done as you would do a normal water change. However, you are simply replenishing your tank with fresh RO/DI water---not salt water! Monitor the lowering closely so as to not reduce it too fast. Usually over a period of 48 hours is fine. By lowering the salinity, you will also be lowering the osmotic pressure of the water. Fish tolerate this treatment very well, in fact, once the water becomes hyposaline, you will likely note a significant improvement in your fish health and appetite. There is no reason to fear this treatment.
Your goal is to drop the specific gravity to 1.009 [48-hrs] gradually. Once all signs of the parasite are gone, then keep your fish in this hypo-saline water for 3-4 wks. If all is well, then you can gradually [over the course of 4-5 days] bring the specific gravity [salinity] back up to normal levels . If all is well after a week, then return the fish to their main tank.
When the fish are eating, offer them quality and varied food soaked in garlic.
To setup the hospital, you may want to think about getting a size tank to accommodate any future population of fish. You have only a few now, but if you get many more, they will not fit in a 10gal if you end up needing to treat in the future. You do not need to get lighting, just the tank, some sort of tank cover like a glass canopy, simple but filter and the means to keep good circulation going in the hospital. You will need an instrument that can read hypo saline water. If you don’t have a refractormeter or a salinity monitor, then get a glass hydrometer [making sure that it reads down to 1.009]. If the water quality in your reef is good, fill up your hospital tank with water from the reef [then just add fresh salt water to your reef to replenish it; just like you would if you were doing a water change, only instead of discarding the water taken from your tank, you will putting that water in your hospital. Since you do not have a cycled hospital tank, be prepared to be doing a lot of water changes on your hospital tank [thus, you may want to get some extra salt if you don’t have enough at home]. You will need to attend to your hospital tank to ensure that it does not cycle. This means testing water quality daily. What ever you do, don’t let the folks at the LFS try to sell you kick ick, melafix, etc., etc. There are only 2 effective treatments for ick---copper and hyposalinity. Hyposalinity is the better treatment in this case because it works equally as well as the copper treatment wo any of the ill effects copper has on fish and the nitrifying bacteria you need to maintain your hospital. Don’t even talk to the LFS staff about your problem…just get what you need to setup a hospital tank!
