disappearing fish

I got this little fella (blue mandarin) the other day at PetCo. There was two but sadly the other one had passed away :// I ended up getting just him. He has been doing fine in the tank, got him copepods to eat and he was eating. This was 5 days ago that I’ve had him. I haven’t seen him since...

Last May I bought a Pearly Jawfish (Opistognathus aurifrons) that was 2-3 inches long for our display tank (24" x 24" and 36" high). It was the first addition other than a few small sps corals. The tank has a deep sandbed (6" to 7" deep) with all the rock structure epoxied to a pvc grid buried...

I have had a biocube 30gal for about 5 years now and my fish disappear consistently. I have never found one even when I know it was there earlier in the day but isn't later in the day. I have looked up in the hood, the back in all 3 compartments, in the sand, under the rocks and have even torn...