Changing aquarium

Helloow, i decided to change my Kirby of tank. i have a bigger tank. I was wondering if i change the tank i will need new water, will it be dangerous for him if i put him right away i change the tank? should i let it kinda repose??? now he's in a 10 gallons, i want to put him in my 15.

How would you guys go ahead for it?

You should set up the larger tank as soon as possible and, yes, let it "repose" for a few days. Beyond that, there are 2 basic things you want to ensure. First, you want the new water to be similar to the old water, so you don't send him into shock. Second, you want to preserve as much as possible of the beneficial bacteria growing in the old tank. These bacteria grow on all the inside surfaces of the tank and in the filter.

When it's time to move him, remove about half of the water from the larger tank and replace it with the old water from the small tank. You will probably want to scoop the water from the top and not transfer any "gunk" that is on the bottom of the tank. Then move as many things as you can from the old tank to the new one: plants, ornaments, filter (or filter media), etc. Do NOT clean these things when you move them. Then move the axolotl into the new tank.

Hi, how is Kirby doing?
From the previous posts there was some concern on the size of your little axolotl..I may be wrong but I'd try not to add to any stress' and leave him/her be while the second tank is running and waiting his arrival. If he is still having problems gaining weight I'd personally wait untill he is eating and showing signs of growth.

ok, but the thing is. i need my 10 gallon tank where my kirby is, to put my fire salamander, thats why....
i had to change radically, but then ill prepare some water on the side to put in his tank.
thanks for the advice.
And no Kirby didnt grow yet. he's still quite small, and decided to eat the less nutricious food.
I'm getting earthworms tomorrow. I hope he will eat them