I have used salt baths for freshwater fish as a treatment and it did work well. This was done with a high content of salt of approximately 5 teaspoons to a gallon of water. The fish was immersed in the solution for a maximum of 5 minutes 3X a day. I now forget why, but I remember that it did work. I have also worked with our local mom and pop fs and we dipped the sw fish in a tub of freshwater (no salt) for a maximum of 5 min to clear up their problems.
The reasoning is that the freshwater causes the parasites to expire as they cannot survive in it at all. I remember they had a very keen eye on the clock while doing this. The opposite is also true of freshwater fish.
Both cases were just treatments and not a constant method of care.
This is a great write up that's helpful and very much appreciated. Thanks to the author.
I have also employed the exact methods as outlined above. However, I am choosy about which type of fish I'll treat in this manner. For instance, I have no second thoughts of treating an ill molly or guppy with a saltwater bath but I wouldn't think of doing that with a clown loach.
In addition, I use this method under two conditions:
1) Very early stages of the fishes' illness...when, IMO, the fishes' immune systems have not yet been compromised or weakened too much and they can recover from the stress of the treatment.
2) If I've tried everything else and this is my last ditch effort to try and save a fish.
I have used this method with both fresh and saltwater fish. In saltwater fish, the effects are quite dramatic as ich seems to explode or fall off (I can't tell which), resulting in a visible difference in the amount of ich on the treated fish. I've used this method with great success to treat fish that reside in a reef tank. Since corals are sensitive to meds, I usually trap the affected and treat them this way if it's a mild outbreak of ich. If it's a bad case, I throw them in a quarantine tank and treat them through various steps. I've added cleaner shrimp to my reef tank and now that problem is taken care of naturally.
The aftercare, IMO, is extremely important. The treated fish should be placed in extremely clean water, not fed for 2-3 days, and kept in a darkened environment to reduce stress. At least that's what I do...just my 2cents