Hi, I am new to Aquarium Advice, but have been experiencing fish loss in my tank. I have a 30 gallon tank and a 10 gallon tank. They are both freshwater tropical. In my 30 gallon tank I have used sand as a base and have a large lava rock as the center piece. I have 2 java ferns on driftwood as my plant life. Currently I have 6 zebra danios, 1 mickey mouse platy, 1 blue ram, 2 velvet swordtails and a regular pleco. In the last month I have lost a Marble Angel and 2 mickey mouse platy's. My Angel apparently had an ulcer that I didn't notice, and the danio's apparently were picking it clean so there were no telltale floaties in the tank. Now my Blue Ram's left eye looks swollen and like their could be blood in it. Any ideas? I am new to the large aquarium sphere and I really love it, but I can't afford to keep replacing fish! Thanks!