Maybe he's just resting, rather than sleeping. I'm quite sure he would wear himself out if he's swimming actively all the time.
My own boy, a veil tail will occasionally stop and rest for a few moments when he's going about his business in the tank- sometimes I look at his eyes and find that he's still looking around while resting, even though the rest of the body is very still.
My own boy, a veil tail will occasionally stop and rest for a few moments when he's going about his business in the tank- sometimes I look at his eyes and find that he's still looking around while resting, even though the rest of the body is very still.