HELP! Salt bath for fungus in juvenile (4th long)

Hi guys,
In need of urgent he'll with yet another fungal infection. Already lost one if my adults 3 months ago, saved another with salt baths and thought everything had settled down.
Just today noticed the beginnings of another fungal infection ( at least I think it is, it's very similar to what happened before), on a young axolotl intended to replace the one i lost. He has some cloudy coloured fungal hyphae on his back/dorsal fin and he's at the surface looking pretty miserable and flushed. My question is, is he too young to salt bath?
He's currently 4cm long, I can't recall his exact age he must be around 4months from when he was layed, but his front legs are fully formed and his back legs are showing the main joint and rudimentary toes.
Has anyone got any suggestions as to why I'm havin these problems all of a sudden. He has not been in contact with any of the old tank (since I have assumed there must be some fungal spores in there still) his water is always fresh and the other adult (separate tank, same-ish water) is fine. Only thing hat has changed around this Problem starting before xmas was moving to the city and having to rely on dechlorinators as supposed to the fresh spring water I was using previously :/
Please any suggestions, I'd hate to lose the little guy he's intended as a tankmate for the other axie.
Thanks all. Ember

Hi
I don't really know the answer to how old? And hopefully someone will be able to tell you,

As for the reason behind it, not sure but do you test your water, do you use a filter, I'm wondering if you could have a crashed cycle? It might be a long shot but worth considering.

Sorry it's not much help, but maybe someone will notice your post and give some better clues and answers.

The only reason my axolotl s got fungus wasfrom bloodworms. So thats an idea, and heat is a cause.id salt bath him in a weaker solution and keep himcool

Hi guys thank you for your replies,
I took the plunge and gave him a weak salt bath yesterday. If you thought transferring an adult axie was difficult this tiny little guy was a nightmare!
He's had 3 baths so far and a lot of the hyphae seem to shed off overnight so I'm very pleased with him
When you say bloodworms gave your axis fungus, do you mean through lack of dietary requirements or the actual bloodworms being contaminated? Cus this little guy only just started eating bloodworms now that he's getting too big for daphnia...I winder if that could be the problem...
Ember20

Not dietary it was the bloodworms itself and can come from any live food, but doesnt usually and lots of dead food seems to make fungus so clean cool salt and on the way to a healthy axi again x