Hi Angry_Platy
Columnaris is a bacterial infection, but just one of many. Since your fish has been ill for an extended period of time, chances are that it does not have Columnaris, but rather one of the other bacterial infections. This might be a good thing, since one of the worst things about a Columnaris infection is the speed with which it can spread to other fish and it will often wipe out a whole tank overnight. The symptoms you describe is typical of a bacterial infection of some sort.
Be that as it may, your fish is sick and needs to be treated. MelaFix is a mild antibacterial and might help him. It is worth trying for a few days, but if you don't see any improvement, I always suggest moving on to a stronger medicine. It's a good idea to do a big water change and tank cleaning before starting it, and another substantial water change each day it is used.
If you were in the US I would recommend an antibiotic, but since they are not available to you, perhaps one of the meds from the UK is. In this case, Myxazin by Waterlife, or Interpet's Anti-Finrot & Fungus Medicine might work for you. Do you have access to either of these?
One of the most important things to do when a bacterial infection is present is to try to determine why the fish is sick and to remove the cause. Many potentially harmful bacteria are present in a tank at any given time, but they do not infect a fish until some form of stress weakens its immune system.
These stresses are often such things as overcrowding, uneaten food in the tank, aggressive tankmates, elevated nitrites, low oxygen content in the water, sudden increases in water temperature, or infrequent or inadequate water changes.
Water changes often do much to improve conditions and lower the bacterial count in the tank. It's a good thing to do them before starting treatment and at intervals during treatment as well, even if you have to add additional meds. Always continue treatment at least the full time the package directions prescribe, or even longer to be sure the disease is fully cured and to prevent these harmful bacteria from mutating into a form that is resistant to that medication in the future.
If you lower the water temperature to no more than 24 degrees C. (75-76 degrees F.) and add an airstone to increase the oxygen content in the water, it will also help by slowing the bacteria's ability to reproduce itself, which will give the medication an additional advantage.
Good luck with the treatment, Angry_Platy. Please let me know how things work out for him.
