I am new to owning a fish tank. I originally had a 10 gallon tank, and had an interest in having a variety of fish. I upgraded to a 30 gallon tank. I have 2 black molly's, 1 Dalmatian molly, 3 Zebra Dano's. 2 gold dust molly's, 2 Cory Dora's, 3 red wag plats, and 1 loach (eel looking). I noticed some of the fish lay on the bottom of the tank. The tank temp is within the green section on the thermometer. I have 2 filters running at all times. Can someone help me out here and give me and idea as to what is happening.?