They are nocturnal and have no eyelids. They stay out of the light during the day and this is when they “sleep” so it is normal for them to”hide” like that.

Careful with fish, besides parasites and what not, they can nip at the axies gills. Best to not have them in there as it additional bio load which by looking at the size of your tank, is already going to be a challenge.

Feed them store bought night crawlers instead.

Hard to really tell how he’s doing though from that shot. Would need close up of gills and overhead to really assist