Concerning your "blue" Axie: I have seen Axolotls similar to this and (unfortunately, I have to admit...) got one myself. If it is what I think it is it's not an "Axolotl" in a strict sense but a hybrid between Axolotl and Tigersal.
You might know that most of the axolotls kept in captivity are somehow hybrids because of the albino-crossbreeding-experiments Prof. Humphrey did in the 60's. What I mean is that it might be one of the "new" hybrids with a larger part of tigrinum.
I know of a "breeder" in Germany who (thoughtlessly in my opinion) did some new crossbreeding experiments between an Axolotl and a neotenic Tigersal to gain some new and interesting colors
some years ago.
"Thoughtlessly" and "unfortunately" because this experiment had some serious and negative side effects, for instance reduced ability of regeneration and uncontrolled breeding and spreading/selling of these animals (the next generations do not look like the first one but still got a big part of tigrinum-genes).
I decided not to rear any of the offspring.
As for the nitrate in your tap water: I do not know any way to get rid of it (at least no non-chemical way) apart from plants consuming this nitrate. A reading of 25 is not too high, though, but you should watch the readings in the tank.
You might know that most of the axolotls kept in captivity are somehow hybrids because of the albino-crossbreeding-experiments Prof. Humphrey did in the 60's. What I mean is that it might be one of the "new" hybrids with a larger part of tigrinum.
I know of a "breeder" in Germany who (thoughtlessly in my opinion) did some new crossbreeding experiments between an Axolotl and a neotenic Tigersal to gain some new and interesting colors
some years ago."Thoughtlessly" and "unfortunately" because this experiment had some serious and negative side effects, for instance reduced ability of regeneration and uncontrolled breeding and spreading/selling of these animals (the next generations do not look like the first one but still got a big part of tigrinum-genes).
I decided not to rear any of the offspring.
As for the nitrate in your tap water: I do not know any way to get rid of it (at least no non-chemical way) apart from plants consuming this nitrate. A reading of 25 is not too high, though, but you should watch the readings in the tank.