Axolotl acting off

[Jaybean]

So when I got my axolotl he had no limbs (he's the black one since then he has grown back his limbs but he's still pretty skinny (the pink one who is his age has since grow to 5 inches (they were 3 inches there) and gotten pretty chunk) but the black just won't gain weight, also he floats alot ik he can swim because he'll swim around or go in the hides but for hours at a time he'll just float I also know he not constipated because I fridged him and he's pooping (my levels are all good at my tank is at a soild 63f) , also he's really weird about eating sometimes he'll eat great but sometimes he'll suck the worm peice in and out of his mouth idk I'm just worried about him what do yall thin

 

[wolfen]

So when I got my axolotl he had no limbs (he's the black one since then he has grown back his limbs but he's still pretty skinny (the pink one who is his age has since grow to 5 inches (they were 3 inches there) and gotten pretty chunk) but the black just won't gain weight, also he floats alot ik he can swim because he'll swim around or go in the hides but for hours at a time he'll just float I also know he not constipated because I fridged him and he's pooping (my levels are all good at my tank is at a soild 63f) , also he's really weird about eating sometimes he'll eat great but sometimes he'll suck the worm peice in and out of his mouth idk I'm just worried about him what do yall thin

make sure you have an air-stone to provide additional oxygen in the water.
also use holtfreters in the water so that the water chemistry is ideal as well.
if he/she is growing then he/she is getting some food, giving a variety of food helps with picky eaters, also at the age they are at they will be movement orientated so live shrimp/fish/worms etc.. they will also eat frozen food ie.. bloodworm/krill/brine shrimp/mysis/chopped mussel/chopped cockle/chopped prawn/beef heart/beef liver etc..

 

[Jaybean]

make sure you have an air-stone to provide additional oxygen in the water.
also use holtfreters in the water so that the water chemistry is ideal as well.
if he/she is growing then he/she is getting some food, giving a variety of food helps with picky eaters, also at the age they are at they will be movement orientated so live shrimp/fish/worms etc.. they will also eat frozen food ie.. bloodworm/krill/brine shrimp/mysis/chopped mussel/chopped cockle/chopped prawn/beef heart/beef liver etc..

I have a bubble bar I do the water chemistry stuff he eats pretty well most the time I feed him cut up worms, frozen shrimp cubes (I make myself) and frozen blood worms (I only have access to frozen)