If the white stuff is very small, well defind spots that look like they're individualized, it could be white spot disease, aka marine ich. If the white stuff looks like a clump of dried, crusty salt stuck to the fins, could be lymphocytsist (sp?). A "dead patch" or grayish looking discolored patch on the side of the fish and cloudy eye could be bacterial/viral infection.
These are most often caused by acclimation stress. I don't think aggression is the cause unless your tank is too small (< 30g), overcrowding could be a stress, but three relatively small fish in a 30 gallon or larger marine system that is well decorated shouldn't have territory problems.
The best treatment:
Get the wrasse into a ten gallon q-tank that is set up with the exact conditions of your main tank (heater, filtration, airstones, temerature, salinity etc), but it shouldn't have gravel, and should have at least one chunk of coral for the wrasse's sense of security. The reason I reccommend a tank is because the glass sides will allow you to watch the progress of recovery much better than a top view bucket. But if you can duplicate your tank conditions in a plastic bucket, you are more than welcomed to try that as well. Tropical marine tanks should have a stable temperature of at least 78F-80F. Stability of temperature is of utmost importance in getting rid of stress-related diseases. Next, gradually reduce the salinity of your q-tank to at least 18ppt, doing so by only 2ppt per 24hr period, with regular removals of the salt water and additions of fresh water. Hold the salinity stable at 18ppt until you see no signs of the disease left and the wrasse is feeding/behaving normally for at least a week. If the disease doesn't seem to go away, drop the tank to 16ppt and then wait and see. I've heard of people even taking their fish down as far as 10ppt, but I have never had to do that. Once the disease is cleared, gradually increase the salinity of the q-tank back up to the salinity of the main tank. As a preventative precaution, you can do a quick 1-minute fresh water dip on the wrasse just before you return it to the main tank.
Acceptible treatment without q-tank:
Drop the salinity of your entire system down to 18ppt, and leave it there. Although most tropical marine books will say that salinities should be at 34ppt (average ocean salinities), that just harbors disease and parasites. An article I read in the Tropical Fish Hobbiest magazine, everybody seriously in the marine hobby I've spoken to, and I myself practice in my store, recommends keeping tank salinities between 18-22ppt normally. I've had no problems with fish at these salinities at all, they seem to live much better at the lower salinities, and the occurances of marine ich and other diseases is much reduced. Slow acclimiation is the key, not more than 2ppt drop within a 24hr period. Your damsel and firefish should also be fine given a slow acclimation.
A traditional way but not best:
Fresh water dip your wrasse. That's take the fish out and place it in a cup of dechlorinated fresh water warmed to the temperature of your tank and leave him in it for at least a minute or two, but not until he looks dead. You'll have to do this twice a day every six hours. The problem with this is 1) osmotic stress from the instant fresh water, and 2) if it is the tank infested with some sort of disease, you'll be putting him right back in a sick system once the dip is done, thus making a stressed fish even more likely to get sick.
Last ditch effort:
Medications. This applies to a FISH ONLY tank. If you have any inverts at all, you will have to remove them, since most medications on the market are lethal to inverts. Medication is also better done in a q-tank because it is easier to dose for small volumes than large. Rid Ich is a malichite green/formalin mixture that works pretty well on marine ich as well as freshwater ich. Freshwater coppersafe is a copper based medication that is also good. FOLLOW THE DIRECTIONS TO THE LETTER. Especially with the copper stuff. Once copper is in your system, it is pretty much in there for good. It is possible to OD on medications, so be sure to do water changes to prevent toxic build-up. Medications do discolor the water, so don't be alarmed by that. It won't hurt the tankmates either if used correctly.
Temperature and salinity stabilities are the two most important things to a marine system. When you purchase a marine fish, always ask the LFS employee what their system salinities are kept at if they haven't told you first. That's why a q-tank is great to have around because you can use it as an acclimation tank. Set it up to the temps and salinities of your LFS, deposit fish, and gradually acclimate it to your system chemistires. This will also allow you to monitor for any diseases prior to tankmate introductions because, well, a sick fish introduced to a system can make an entire system sick.
I hope this helps you.
~~Colesea
