Hello. As I was slightly rearranging rocks, driftwood and putting floating plants back in the sand, I noticed my neon tetras huddled up. I counted them and there were 8 neon tetras, but we originally bought 9. I am scared that one might be dead, stuck in the filter, buried in the sand, crushed by the decor idk and I'm scared that maybe more are dead as well. I screwed up so bad. Please help. Thank you.