I have 11 neon tetras in a 20 gal tank. Recently they’ve been seeming tired and not moving around the tank like usual. They still swim, and occasionally school, but they just seem tired and often stay in the same place for a couple of minutes. I had an issue with some fish being aggressive but they appeared to work it out, could that be why they aren’t as energetic anymore? They only get a burst of energy when I come up to the tank. They are eating well, no signs of visible disease, and water parameters look good. Is this kind of behavior just normal or could it be a sign of unhealthy fish?