Hi campbells,
My, it seems like you've been having a run of annoyances lately!
I wonder if there may be several things going on at once in your tank. If you have had the axolotls for a couple of months, it could be that the tank is in the middle of a cycle (more info
here and
here). An excess of ammonia/nitrite could put an axolotl off its feed and make it susceptible to a variety of other complaints.
The white fluffy stuff sounds like a fungus, but I'd hate to "diagnose" it as such without photos - can you provide a picture or two? Fungus can grow on an axolotl under a variety of circumstances (especially on an injury) and is more likely at warmer temperatures. What temp is the water in your tank?
I keep guppies in my tanks, too, and have never known them to bite a healthy axolotl, but if the axolotl has an injury, the guppies will nip and nip at it, even down to the bone. Could your axolotls have injured each other? This is not uncommon, particularly if the axolotls are young, hungry, or do not have enough places to hide from each other.
As to the leak (I live in dread of having one, you poor thing) - did you repair the leak with some sort of epoxy or silicone and reuse the tank or did you chuck it and get a new one? If you repired the tank and put the axolotl back into it, perhaps there is some chemical in the glue that is leaching into the water?
Lastly, moving the axolotl a lot can cause stress on its own. Not eating is a common response in this case - but it wouldn't directly explain the white goo.
Hopefully we can quickly narrow down to what is going on.
-Eva