slime coat shedding?

[axolotl nerd]

my lovely mudkip has always been my happy and rambunctious gal, and is rarely “down in the gills,” but i’ve noticed her slime coat appears to be damaged; pictures below. any idea why? we did have an ammonia spike recently, as she quite enjoys hiding her waste behind rocks and plants so i can’t clean it as effectively, but other than that i’m not sure why it would be this way. in the photo, there’s also some sand on her tail, so disregard that bit, but the area that is circled is cause for concern.
thank you