Ich is pretty terrible, and puffers seem to be susceptible to it, no matter the species. So, ich is a parasite, and its life cycle runs in stages. I recently treated my South American Puffer (brackish) successfully, but it was a rather tramatic experience, and oddly enough he had the ich longer than all the other fish in my aquarium. I tried alot of different methods, so I can't be 100% sure what all worked, but I'll tell you what I did.
While ich is on the fish (the spots you see) it is immune to all medications. Its typical life cycle is something around 3 days. During that time its feeding and gestating on your fish. Then the cyst will fall off and sink to the bottom of you tank, leaving a wound in your fish and weakening it. At this time it will burst and release its spores into the tank, possibly infecting the rest of your fish. The cycle runs until the ich runs out of food, or dies.
Ich's lifecycle is directly affected by the temperature of your tank, the lower the temp the longer the lifecycle, the warmer the shorter. Ich cannot reproduce in temps above 86 F. So, firstly, you should raise the temp in your tank. Gradually of course, say maybe 2 degrees every 24 hours, until you're at 82 or so. It is possible to raise the temp to 86 and kill the ich, but you run the risk of weakening an already distressed fish. This should probably be a last resort, although I've read that some people prefer this method, as it is without medications. Remember ich is immune to medications while its on your fish, so by raising the temp and speeding up the life cycle your increasing the speed at which its dropping off your fish and entering into the water, where it is susceptible. You might also consider dosing melafix http://www.aquariumpharm.com/Product...x?ProductID=56
. When the ich leaves your fish it leave that wound, and you will want to boost the immune system of your fish with that Melafix. If you do see a secondary infection start to occur (fungus or the like) dose with Pimafix.
Secondly kent ich medications say to have a proteins skimmer running in the tank, do you have one? Kent Marine » Rx-P | Products
I'm not sure what the effect this will have, but it seems to indicate that the medication is designed to be used with a skimmer, so it may not work correctly without one.
Fresh water dips for salt water fish, and visa versa, work through changes in salinity in the environment. The process leaches water from the cells of the fish, and the ich. This can have positive results, but it is highly stressful to the fish. I personally had limited success with the treatments, but you may have better success. A word of caution. How long has you as your fish been sick? A freshwater dip at the time may cause more harm then good!
Ich, as I've said before, has a 3 stage life cycle. You may not see the infection on the fish, but the cysts can still be in the tank. Its important to continue dosing the tank, because the cysts that have fallen off your fish may not burst immediately, and when they do, (within three days after your fish seems cured) you want the medications, or temperature, or both, to be there to kill it.
When my SAP (and the rest of my tank) were affected, I treated 3 different medications, ich-rid and the like, malikite green, and salt. Fresh water ich is cured in some cases by salt. I also raised the temp to 86 (had to run too heaters to get it there). No fatalities, but the fish were stressed. Good luck! It'll be tough, but if you're fish is a fighter you'll get through.
I should also mention, stressed fish are more likely to catch ich, so watch out for stessed behavior.
edit: to quote David from the sick clown topic:
Originally Posted by David S
Tank is way too small for your fish,Looks like ich,take em out and qt them.treat and leave tank empty for at least 8 weeks to kill off in the tank.
Copper treatment or
Decrease the salinity of the water (1.009-1.010). A low salinity environment will kill the parasite and is harmless for most fish. You should keep the low salinity for 2-3 weeks. If you use this method it is important not to raise the salinity too quickly once the treatment is done.
ich won't take that long to die in the main tank, remember the life cycle, but it would most definitely be gone by then.