first i had a emerald crab die,bought a flammin angel it died two weeks later then my coral shrimp died a few days after.my lawnmower blenny is lyeing on the sand and no fish are eating.i bought two cardinals yesterday and now i no i must have a problem.temp,salinity is good.tested water at pet store yesterday they said my nitrates were high.i did a water change and tested they said it was good.i had my clowns over a year and they are not eating,i no something is wrong please help.let me add when i bought the flammin angel it had like a scale missing on the side near its gill.never thought anything of it because it was acting normal and eating.did i buy a diseased fish.also yesterday i found something weird on the bottom of my tank ,it looked like a small jelly fish about 3/4" in diameter