Constipated axolotl?

I have had my new axolotl for about a week now, and up until a day ago it was eating earthworms like a little pig, but now he has gone off his food, and I have also noted that he seems to not be pooping, as I have not found anything in the tank since I got him.

His diet consists solely of earthworms that I grow myself in my own worm farm.

The tank he came from at the shop was a bare bottom tank, and the tank he is in now is also a bare bottom tank too, with no substrate at all, except for the live plants that live in a container with some fine black sand for them to root in.

the axolotl seems to be a older one, and has the darker tips on the ends of its toes and is fairly large, so I think he may be mature, and that I could be over feeding him somewhat, or do axies take longer to digest food?

If I am over feeding him, and he is not pooping because of this, I assume that a holiday in the fridge for a few days could be in order.

If he is adult, you may only need to feed every couple of days. Maybe try alternate days for a bit. Keep him cool and see if anything else changes.

An update.

I have started to feed my axie every second day, and he has not made any mess that I can see (his tank is a bare bottom tank) and he has not started floating, nor has he lost his appetite, and is swimming and is as active as ever.

I guess I'm worried that he is a unusually clean animal.

should I try fridging him anyway?

I wouldn't

you probably don't see the mess because it has already dissolved, if you look carefully between decorations and such you may find something, or else your axie hasn't pooped yet, which I don't find unusual for an adult since mine only does it about once every 7-10 days... and she is quite normal for an axie!

just keep observing him and feeding as usual

Thanks for the advice, I'll keep a eye on my axie.

I have a filter that turns the tanks water over a few times a hour, without making much current, and I am religious when it comes to how clean the tank is. I do see what looks like dirt when I vaccum the tank daily, so I guess that could be it.