So on Friday I picked up three lyre tail anthers that were being quarantined for me by my local fish store. When picking them up, they were extremely healthy looking and aggressively ate. I brought them home and drip acclimated for 2 hours until salinity and ph matched and then put them in. Over the few days, they were still eating aggressively. I fed twice a day using LRS reef frenzy. The only thing I noticed was that the strongest fish was chasing the other two around like normal anthias behavior. On Sunday I noticed one of the anthers had some torn scales near its eye. I assumed it was injury from the strongest anthias. Yesterday (Monday), it was time to do my routine water change which is every two weeks. They were eating aggressively still and looked fine besides that one with the torn scales. I was doing a 15% water change and matched my salinity, pH, and temp to my tank's water. I confirmed that they all matched ideally. As I was doing the water change, the anthias went and hid in the rocks as they usually do when they're scared. This morning though, I woke up and found the anthers with the torn scales being eaten by hermit crabs and snails. I quickly took it out and checked my parameters. Ammonia, Nitrite, and Nitrate were all 0. The other two anthers were hiding in the rocks still which was odd because they're usually out and about. I tried feeding and they didn't eat but my two other clownfish and Midas blend were still eating aggressively. I went to shower and found the other two dead.. I have no idea how this happened so quickly and what could have happened. My other fish are acting perfectly normal and look super healthy. What could've happened? I'm really confused..