Hi
You'll need to do saltbaths twice a day until at least 5-7 days after the fungus has dropped off.
Saltbaths, are done for 10-15 mins maximum, no longer than that.
2-3 teaspoons of sea salt/tonic or aquarium salt/uniodised table salt per litre or 2 pints of dechlorinated water.
Use a plastic container, with lid, that will fit your axie lengthwise, ie 2l icecream container or other.
Put the dechlorinated water in the container, add the salt - stir to dissolve, or if using aquarium/tonic salts you may need to crush them if they're chunky and stir till they dissolve.
Add your axolotl, put a lid on it, so he doesn't take fright and jump. Set a timer for 10-15minutes so you don't forget.
When the saltbaths are finished he can be returned to the tank, if the temperature is below 20C. Higher temperatures will just add to his stress.
Now you have to eliminate what may have caused him/her to develop fungus, if there are no sharp edges in the tank or new companions (ie fish or other) that may have been added without quarantining for 30 days.
So what is your tankwater temperature and have you tested your water parameters - ie: for ammonia, nitrite and nitrate. Axolotls tend to develop fungus if they have a wound or if they have been stressed through water quality and water temperature or something else.
Changing your water once a week is fine if your tank is cycled, but when did you move home and how long have you had this tank setup? Your tankwater may very well be going through a cycle or minicycle which is entirely normal if you emptied all the water out to move your axolotl/tank etc due to house move; and if that's the case you'll need to do more frequent waterchanges than once a week (ie 20-30% waterchanges every day or every two days) see:
http://www.caudata.org/cc/articles/cyclingEDK.shtml and
www.caudata.org/cc/articles/waterquality.shtml
You may need to test your tankwater. If you don't have freshwater test kits, preferably the test tube kind not the all in ones, then take a sample of tankwater to the petshop and ask them to test for ammonia, nitrite and nitrate. Ask them to write the results down and then DON;T buy anything from the petshop to fix anything (ie they may try and sell you something like ammolock, or something similar to get rid of the ammonia or nitrite). Basically if ammonia or nitrite levels are over 0 you need to do at least 20-30% waterchanges every day or every two days rather than weekly. The chemicals the petshops advise to buy are only temporary fixes and can cause more stress to your axolotl; whereas the waterchanges will fix things and keep the toxins down while your axolotl is in the tank.
Ideal tank temperature is under 20C. Anything over 20C and you'll need to cool the tank and maintain the cool temperatures, using polystyrene round the back and sides of the tank in conjunction with frozen bottles of dechlorinated water and/or a fan blowing across the surface of the tankwater will help bring the tank temperature down a few degrees See:
http://www.caudata.org/cc/articles/cooling.shtml
( my poor axie has damaged his gill, not sure when and how it happen, think it my have been when i was moving home but i tried my best to be gently with him. The gills that has been damaged isn't bleeding or anything but has white fluffy stuff (look like it my be fungi) forming around it but i'm not really sure. It must hurt a bit cos when i try and touch it he gets a bit grumpy with me. I change 20-30% of his water every week so it is pretty clean.... any help with what to do would be great as i am new to axie's. 