I am new to the hobby and just dipping my toe in the water so to speak. I have a 45 gallon FO
tank. Rema canister filter and Penguin 400. The tank is 5 months old with an established cycle. I started slowly and introduced 2 yellow tail damsels and ran that way for about 2 months. When I got a diatom outbreak I added 4 red legged hermits, a sand sifting star, an a dozen asterea snails for clean up crew. everything was great so far. 3 weeks ago I bought a Coral Beauty Angel and a Yellow Coris Wrasse and introduced them. All the livestock appeared healthy and were eating just fine. After 2 weeks I found the angel dead on the bottom of the tank. Yesterday the wrasse was dead under the sand. One of the damsels is nowhere to be found and the other is still swimming. All the clean up crew seem to be ok. Specific Gravity has been maintained at 1.025 and ammonia and nitrites are at 0. Low nitrates (10ppm) and pH of 8.1. I use RO
water and do weekly changes of 10-20%. Anyone have any ideas what might be wrong? Could it be a disease? How do I find out? As I said, the fish appeared healthy and were eating and swimming fine. Any help would be appreciated. I'd like to continue in the hobby but this is frustrating as I thought I had things under control.