Question: Broken toes/fingers?

[MyLittleComet]

So when I got Meteor, he was already an adult and his back left foot had two nubs for toes along with two normal pointed ones, missing a fifth.
Now, his right back foot has two nubs in addition to three pointed, and his right hand also has a numb. I noticed last night that he had little fluffs of fungus on his hands and feet and have just given him a salt bath (he has holtfreters solution in his tank too)
Im wondering- how is this happening? Why are they breaking in the first place and then not regenerating properly?
He has no tank mates aside from snails. His parameters are normal. I have however noticed that he digs up the sand. I dont see him do it, but he digs it up at the front of the tank so it slopes down. Why would he be digging? Neither of my other lotls do this. I've attached pictures of him and his tank set up

 

[wolfen]

what variation of holtfreters are you using?
your sand may not be suitable for axolotls, if it is too course then he can quite easily be wearing down his toes digging and walking on it, unlike adult terrestrial forms of salamander larval salamander forms have very delicate digits which are easily damaged.

 

[MyLittleComet]

what variation of holtfreters are you using?
your sand may not be suitable for axolotls, if it is too course then he can quite easily be wearing down his toes digging and walking on it, unlike adult terrestrial forms of salamander larval salamander forms have very delicate digits which are easily damaged.

I've been using the recipe found here

The sand is the finest grain aquarium sand i could find. Should I remove it from his tank then?

 

[wolfen]

in cases where there is fungal infections holtfreters can be increased to 100% to treat and then just using 50% for health, with holfreters the percentage can be increased and decreased without any issues unless there are plants in the tank.
the original axolotl.org recipe is here Axolotls - Requirements & Water Conditions in Captivity which is about the same as https://ambystoma.uky.edu/genetic-s...Issues-1-12/archive/Issue 3/09-16brothers.pdf which also includes the use of magnesium sulphate (epsom salts) as well.
if you axolotl is continuing to wear down his digits it might be better to either remove the sand altogether or replace it with play sand which is a finer grain.

 

[MyLittleComet]

in cases where there is fungal infections holtfreters can be increased to 100% to treat and then just using 50% for health, with holfreters the percentage can be increased and decreased without any issues unless there are plants in the tank.
the original axolotl.org recipe is here Axolotls - Requirements & Water Conditions in Captivity which is about the same as https://ambystoma.uky.edu/genetic-stock-center/newsletters/Older_archive/Issues-1-12/archive/Issue 3/09-16brothers.pdf which also includes the use of magnesium sulphate (epsom salts) as well.
if you axolotl is continuing to wear down his digits it might be better to either remove the sand altogether or replace it with play sand which is a finer grain.

Gotcha. Thank you so much!