Ok so you refuse to answer some basic questions to try and help determine the source of your problem so I will just give you some advice to help you.There were all small. It is not ammonia issue. I’ve done QT my own fish before and this is either ich, fluke, or velvet. All the other fish are eating and not light sensitive. I had the melanurus death after 3 days. Possibility the ornate leopard. Wrasses are really prone for flukes.
Patience is the primary objective is this hobby. If you drop way to many fish as you apparently did into a new tank with a beginning cycle you are walking the path to disaster as you now are witnessing. Stress leads to disease because the fish immune systems get compromised. New tanks do not have the biological support in place for large numbers of fish which leads to problems like 02 deprivation and other parameter fluctuations. Because things seem to be dying overnight that indicates 02 because tank 02 decreases overnight and if a new tank is overstocked like yours then you get dead fish in the morning.