Hi everyone, I have a Juwel Lido 120 L tank with about 8kg's of live rock , live sand , HOB skimmer , factory fitted filtration. Water params - Amonia - O Nitrite - O Nitrate - very very little to 0 PH - 8.2 Temp 26 degrees C. I do a 10 - 15 % WC once a week. Stock 2 Occelaris Clowns , 1 Fire Goby , 1 cleaner shrimp , 1 coral banded shrimp , 2 turbo snails , 2 hermits (blue and red legged) , 4 - 5 various other smaller snails, 1 Frog Spawn coral , 1 BTA , 1 Brain Coral , 1 Zoa colony , 1 Clam , some shrooms and a rather large leather coral. My question is this all my corals are doing GREAT and growing (except for the BTA but Im working on him). MY fish are active and eating (and hosting the BTA ) but everytime I introduce a new fish it lasts for about a week then keels over I am currently losing my Yellow Tang that I bought on Sunday. What am I doing wrong?? Any fish I put in the tank other than the ones already in there seem to die within a week maximum 2 weeks I've lost 1 regal tang , 1 yellow wrasse , 1 six stripe wrasse and now the yellow tang... We also have quite a bit of coraline growing in the tank so I think everything is fine...? Please help out!!! Thanks!!!