My fish are staying at the top of the tank....
I bought the Fluval Edge tank and have had it up and running for about a week and a half now and up until yesterday everything was going fine.
Yesterday I bought new fish and 2 live plants to add to the tank. I added the fish and the plants and everything was good. When I got home from work last night the tank had turned slightly cloudy, three of my fish were dead and all the rest of the fish were swimming at the top of the tank gasping for air it looked like. I immedietly removed the dead fish and did a 25% water change to get rid of any bacteria in the tank. The fish started swimming around like normal again. When I woke up this morning all the fish are back at the top of the tank and won't leave the surface.
What do I do??