Possible nitrite poisoning with Axolotls?

[axolotl30]

Hello,
I have a 10 gallon tank with a sponge filter set up as a grow out tank for 2 young Axolotls. I allowed 5 weeks for the tank to cycle before purchasing them. I have had them for about 2 months and they have done great. My wild type is now about 5.5 in (14cm) and my melanistic is 3 inches at most. I have them separated due to the size difference and they are both aggressive eaters. They recently seemed to lose their Gil filaments overnight. The next day they were spitting their food out and then losing all interest in food. This was a big red flag as they were previously very willing to eat twice a day if offered. Then they developed pale patches I immediately fridged them before their condition could get worse. I am thinking nitrite poisoning? They have wanted to stay in the bubbles from the sponge filter. When I changed their water in their fridge tubs I noticed their skin was peeling off in the water.
background:
Daily 30% water changes (dechlorinated)
Spot cleaning all waste
68F/20C tank temperature
Bare bottom
Fed cut earth worms daily
Water parameters ideal before spike
Ammonia and nitrite spike after gill loss
No tank mates

I have done a 60% water change on their 10 gallon while they are in the fridge. I am wondering if they would benefit from salt baths or if it would cause more stress? I have also heard of tea baths or using almond leaves in their tub.

Today I set up a 40 gallon tank for them to start cycling in hopes they will heal in the fridge, return to their 10 gallon for a few weeks, and then to the 40 gallon once it is cycled. It will have a Marineland canister filter rated for 55 gallons.

I attached a picture of before and after the problem with my wild type. This was before he got the pale patches. The smaller melanistic is experiencing the same problems

I would appreciate any suggestions that might help my axies, thanks

 

[Murk]

Well, yes, if you measured an ammonia and nitrite spike, that is a very likely cause.

Definitely no salt baths unless you see actual fungus growing. Salt is very damaging to their skin, and their skin is already very damaged. Unless you see any fungus, salt baths do more harm than good.

For ammonia and nitrite damage, fresh water and time to relax is the best cure. Keeping them fridged might help, but not if it impacts your ability to give them clean water.
They'll probably be unwilling to eat the coming days. Try to tempt them with small, easy food, but don't panic if it takes a few days for them to regrow their appetite.

The most important thing is that you find out why you had a sudden ammonia and nitrite spike, so that it doesn't happen again.
If you can get the axolotls in clean, fresh water, they will probably heal well enough. If you put them in an uncycled tank or a tank that is likely to get more ammonia/nitrite spikes, this will only get worse.
Do you have any actual numbers on the water parameters? That might help.

 

[axolotl30]

Nitrates were 0, nitrite was 1.0, about 100 on hardness, 120 alkalinity, 7.5 pH. I lost the smaller melanistic , however the wild type has began recovering and will return to his grow out tank that is now safe, then the 40 gallon after it has cycled. This time I will keep up with 50% water changes instead of 30% until he can be switched to the larger tank. Thank you for your response!