Hyposalinity is Osmotic Shock Therapy [OST]. No, your fish aren't subjected to the shock, but ick parasites are. Essentially, O.S.T. simply places the infectors [ick] in an environment in which they cannot hope to survive while the host, (or infected fish) can. This remedy WILL NOT work in reef systems or invert tanks as it incorporates lowering the salinity of the entire system to 1.009 SG---this SG/salinity being too low for inverts, LR or LS.
The method of lowering salinity/SG is simple: Over the course of 48-hrs, salt water in the tank is replaced with fresh RO or DI water in small increments until a SG of 1.009 is achieved. Maintain pH, as pH tends to lower is hypo-saline water, and you need to maintain same pH. Watch for pH, especially at night. If you are not using a salinity monitor which gives more precise readings, then try using 2-brands of hydrometers to make sure that you get an accurate reading. The SG MUST be dropped to 1.009, nothing above that will do. By lowering the salinity, you will also be lowering the osmotic pressure of the water. The parasites NEED high osmotic pressure to convert saline water into freshwater. All marine animals need freshwater as we do [parasites are considered marine animals as well, BTW]. They just convert it differently, usually via their tissues. Reduce this necessary pressure and the ick will die—explode actually. As a higher life form, the fish will do fine with this treatment.
Maintain the 1.009 SG in the tank for 4 wks AFTER no visible signs of ick are present with your fish. After that time, you can slowly, over the course of several days, raise the SG back to normal levels in the hospital. Take longer raising then you did lowering the SG. Leave the fish in the hospital for 5-7 days after returning the SG to normal levels before moving it/them back home.
In the meantime, feed your fish garlic soaked food several times a week, and, if you can get either Zoe or Zoecon, alternate feeding your fish with these excellent vitamin supplements. No need to feed with vits and the garlic at same time. MORE is not better either with fish meds, additives or supplements. Garlic is a natural parasite repellent for ick. It also has mild antibiotic qualities as well as being an immune booster. Anybody ever hear about giving their dogs garlic tabs to get rid of flees???? Well, it works with fish too---to an extent! No, don't add tabs to water. use fresh crushed garlic or garlic extract to soak the food--don't add the garlic to the water!
<a href="https://www.saltwaterfish.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=14&t=000002" target="_blank">TerryB's FAMA article on Ick and Treatment Including Hyposalinty </a>
