My 240g reef tank measures 96"x18"x30" (lxwxh). A 50 gallon refugium and a 30 gallon sump are attached. Circulation is from 4 Vortech MP40WES, an OM-4 way/Sequence Dart, and a Sequence Hammerhead main pump - all intakes and overflows are screened. The top of the tank is not currently screened. Aquascape provides LOTS of caves/overhangs. Last Sunday I moved 11 fish (Macauliceps Tang, 2 hawkfish, 2 chromis, 2 firefish, copper-banded butterfly, 3 pseudanthias) from quarantine to the main DT to join a sailfin tang and bangai cardinal, several shrimp, 2 small crabs, 3 anemones and assorted corals. Two days ago one of the firefish turned up missing; yesterday a chromis was absent; and this morning the banded hawkfish was gone. I've observed no aggression, and there are no carpet surfers to be found. I'm stumped. Anyone have ideas?