here's an excellent read from cichlid forum.
Treatment
Once you notice that your fish has lost an appetite for food (and is not just holding fry in her buccal cavity), you should remove it and begin treatment immediately. There are two effective treatments for Bloat that I know of. The first and most common is Metronidazole (Emtryl or Flagyl), and the second is Clout. The treatment should be preceded by a 30% water change (in an effort to improve water conditions) and increased aeration, followed up with a 50% water change. It is also a good idea to remove any biological filters you may be using, even though these drugs claim they don't harm denitrifying bacteria. The initial 30% water change is not necessary if this is a hospital tank not previously in use. The water change is important partially because you won't be performing water changes for the duration of treatment, not to mention the fact that you have just removed a large percentage of your bacteria. Store your filters in some of the water you removed from the tank prior to treatment.
In addition to treating your tank with either one of these drugs, it is also recommended adding an Epsom salt/Table salt mixture to your tank. Mix the two half-and-half, and add a handful of this mixture for every ten gallons of water. Epsom salt is a natural laxative and will help your bloated fish lose some of the water it has been taking on. Epsom salt is very cheap, costing something like $2 for 3 lbs. It can be obtained from any grocery store or pharmacy.
If treating with Metronidazole, add 100 mg (about 1 ½ scoops) for every 10 gallons (or 38 L). Repeat this dosage every two days as required. Fish usually heal (if they survive the disease) within a week. You can typically tell when this occurs because the infected fish will regain its apetite. If, on the other hand, your infected fish has retained its apetite, you can easily administer this drug with its food. In a disposable cup, add some water from the tank, a few fish food pellets, and a single measure of the drug. After the pellets have soaked for a few minutes, pour all of the contents of the cup into the tank. When administering this drug, turn off any UV, ozone, or chemical filtration as these disable the active ingredients of the medication. Following treatment, perform a 50% water change. SeaChemTM and AquatronicsTM both sell drugs containing Metronidazole, the former being called Metronidazole and the latter being called HexamitTM.
Treating Bloat using Clout is also relatively simple. As already mentioned above, before you begin treatment, remove any carbon you might be using in your filters and perform a 30-40% water change. Using a disposable cup, dissolve in some tank water one tablet of Clout per 10 gallons (round up if necessary). Pour the mixture into the tank just a little bit at a time, perhaps taking a half hour to administer a complete dosage -- this drug can be very strong and so it is important to follow this guideline so as not to shock your already stressed fish. Repeat the same dosage for the next two days, again performing a 30-40% water change beforehand. Daily water changes are essential for Clout's maximum effectiveness. The water changes also facilitate the removal of the old, disabled chemicals. Three days of treatment should be sufficient if the inflammation is not too severe, otherwise treat for a full five days. If after five days, you still don't notice a change, then resume treatment again after a two day hiatus. Once you have concluded the treatment, perform a final water change 24 hours after the last dosage.
Both drugs are effective at stopping the spread of Bloat in the tank. CloutTM is a very strong drug that was developed particularly for fish. Most other fish medications have human counterparts including Metronidazole. In my experience, Metronidazole has only been effective at stopping the spread of the disease and not at curing fish already displaying symptoms. CloutTM, on the other hand, has proven somewhat more effective at curing bloated fish. I should warn you, however, that CloutTM will turn the water blue and stain the silicone in your tank, as well as any airline tubing you may have. If you are not careful with it, it will stain anything else it comes in contact with. While it has proven effective for me, I wish I had know what it was going to do to my tank. I still would have used it knowing this, but I just felt gypped afterward. And so, I am just alerting you.
Additional note: When using these or any other medications, it is a good idea not to turn on your hood lights while treating your fish. These two drugs don't have any active ingredients that are disabled by UV rays like many antibiotics, notwithstanding, the dark atmosphere will help your fish to relax and recuperate.
Metronidazole works better at elevated temperatures (e.g., 80°F), but aeration should be increased because the O2 content of water decreases with higher temperatures. Elevating the temperature of the water can be beneficial also because it increases the fish's metabolism and heightens its immune response, while also hastening the life cycle of the parasite, thereby shortening the time required to cure the fish. □
Good Luck