Question: Floater?

I have two juvenile wild type axolotls in a small rearing tank. One of them is fine but the other floats at the surface and bobs back up when he tries to swim down. He has a healthy appetite and is otherwise very healthy. I change the water daily and have lowered the level so his feet can touch the bottom. Is there anything else I can do?

Axies tend to float more when they need to poop especially if it's more the rear end that's floating. It's also possible that your little friend has swallowed too much air whilst eating (usually if snapping at the surface of the water, rather than searching along the bottom of the tank). Both of these things can be eased by fridging the axolotl - Axolotl Sanctuary
Of course, some axies, especially when younger, just enjoy floating around. But, since you've said yours has trouble staying further down in the water, this might not be the case.
I'd recommend fridging the little guy, as it won't do any harm even if it doesn't actually help. It literally chills them out. The metabolism slows down in cooler temperatures, so the body expels waste (poop), but it also calms them down. A slower metabolism may well put your axie off it's food whilst in the fridge, but this is normal + they tolerate it just fine for short amounts of time (I'm talking days / wekks, rather than hours + minutes though - continual temperature fluctuations are bad for axolotls - make sure you warm yours up gradually after you've finished fridging, so it doesn't go into shock)
There could well be other possible reasons, but I can't think of any common 1s at the moment

Thanks for that. I left all of the stuff ready to "fridge" him when I got home from work and he is now sinking to the bottom with no problems at all! Useful to know for next time though, thanks again.