Anyone ever had thier fish make noise? Pure curiosity. In the middle of the night (dont ask why Im sitting in the dark at 3am in front of my fish tank

) I have heard my African Knife make two different noises. One was kinda a bubblie (for lack of any good description) noise and the other was a distinct clicking noise. He was up at the top when he made them both. Pretty sure it is just a noise they make when they grab air. But it is still pretty neat!!! Anyone else got noisy fish?
on a side note- the other noise I hear occasionally is him trying to jump and hitting the top (the tank is completely covered so he's not gonna jump out). But do you think he will hurt himself? Anything I can do to make him more comfy? His jump isnt him being startled, it happens in the middle of the night in complete silence.