After the lights go out, my silver seems to splash and smack up against the lid, every 30 minutes or so. It's other inhabitants are a clown knife about the same size, little over a foot, a few bichers and fire eel. Could it be getting spooked by the cl or is this a normal thing? If the tank wasn't in the bedroom i wouldnt care. It's fins are fine, but the cl does dart at everything during the day.. Is there any dithers that are wuick enough overnight? Thanks