Stubby toes

Today I was interacting with GD and he was climbing on (clinging to) my hand when I noticed something different about his back toes. I don't really know about axolotl's toe anatomy but he has always had claws or toe nails that I can feel softly scratching my skin and you can see them too, a bit pointy, dark, and curved downward. Today it seems like his back toenails have fallen off or filed down or something? I don't have a camera that can focus on such a small detail, otherwise I would show you but his back toes now look round and geckoish compared to his front fingers which are clawed. I don't see any signs of fungus or rot, the skin on the toes looks clean, just soft and rounded. It could be his back toes were always like this and I didn't notice until now because he was too small before. Do they even have nails? Can they fall off? What would that mean?

His back toes are still getting shorter/stubbier. There is quite a drastic difference now between the back toes and front toes, is this normal when an axolotl becomes an adult? Once again, I'm sorry I can't post photos...
I don't see any visible fungus, but it's like the toes are rotting away very slowly. There are no visible open wounds or exposed flesh, but it's like the toes have less and less... bone in them?

Edit: I don't know what's wrong, but as I was thinking about possibilities I wondered if it might me a vitamin D deficiency? I read that axolotls are sensitive to light, and since I moved GD from a 5 gallon to 12 I have never used a tank light at all, nor does the tank get any sunlight. GD has also seemed more sluggish and lower on energy, but I assumed that was just part of growing up. I will install a tank light and see if anything changes.

So... I feel like I'm talking to myself here, but in case anyone else has the same problem and finds this thread later on, I'll continue to update a solution as I find one.

Keeping the light on for an hour or so a day has improved the water quality if nothing else. The plants are looking greener, and I think their browning might have been making the water quality lower. Some stringy ugly brown alge has stopped growing on the filter and didn't come back after a water change, the now healthier plants must be out competing them. Also my axolotl seems to enjoy or at least be curious about the light because when it is on, he will hang out underneath it. He is also getting more active, back to his old self. So, while low light and hides are good for axies, there is some benefit to a little bit of light.

I was thinking since only the back toes were shrinking, it could be a localized bacterial infection. I applied some very diluted tea tree oil to the back toes and have been giving daily tea baths. I tried both plain black tea and plain green tea, because green tea has higher antibacterial qualities. While he did fine in the green tea bath, after I put him back in his tank he was acting "drunk" swimming into walls and the floor (not frantically, just extra clumsily) so since I have stuck with black tea.

The toes, with the exception of one that got very short, are showing small signs of regrowth! Two even have the beginnings of toenails again.

Sorry I don't much to offer but I am definitely keen to know how it goes. It sounds quite positive at the moment and he sounds like he is on the mend.

Sorry for digging up an old thread, but I would like to post the "conclusion." After I treated the presumably bacterial infection with daily tea baths for a week and a single application of diluted tea tree oil to the back toes, they stopped shrinking and the tips seemed to heal, but they stayed stubby and did not show further signs of regeneration for about a month.

2 weeks ago I moved and decided to get a new tank, this time I was specifically looking for a glass tank because of this comment:
"Although we successfully use plastic containers, they must be kept very clean. Plastic tends to support the growth of a bacterial scum along the bottom and sides of the container. We have found that if this scum is not cleaned off periodically, the axolotls will develop sores on their toes and feet that will not heal. Instead the skin retreats up the leg and the toes eventually die and are sloughed off. If this happens put the axolotl temporarily into a glass bowl. Add a few drops of mercurochrome (enough to tint the water a pale orange) to the water as a disinfectant, and change the water frequently. The axolotl will heal nicely, and the toes will probably regenerate."
found on Guide to Axolotl Husbandry.

I used a new filter but kept the sand, rocks, and marimo from GDs first tank, and he moved into the new 15 gallon glass tank a week ago. I did not treat with with mercurochrome or anything else, because it seemed the infection had long since died, but the toes were not regenerating. I noticed nearly an immediate change in appetite and activity in the new tank (both increased) and within one week the toes have regenerated their length and are very close to reaching their full length. In just one week they tripled in length.

I am not sure exactly what caused the toes to rot away, what was hindering their regeneration, or why they regenerated so quickly after 1 week of being in a new tank after a month of no signs of improvement, but as this article suggested after not healing I a plastic aquarium when GD was transferred into a glass aquarium he regenerated quickly. There are most likely other factors at play, however.

I know this thread has been inactive a while, so I thought I would ask how your guy is doing? I was sent an axolotl from an individual that mentioned "it might have a foot problem". When I got her, the toes have been eroded to the point where her bones are sticking out and she is showing signs of infection (streaking up the legs along the vessels and redness at the sites). She is currently being evaluated at the vet, but I am researching to make sure I give her the best set-up I can while she is healing. I have her in a glass, bare tank at around fifty degrees. She is receiving antibiotics by mouth (tube with food as well), but just wanted to know if you have anything to add for me. I want to save her if I can.