I got a 12 gallon Nano Cube for Christmas and got it up and running for freshwater. I added six neon tetras yesterday . . . all seems well except with the pump on they look like they are trying to swim in a raging underwater current. Guys at two different pet stores said they would be OK but when the pump is on . . . and I think it's supposed to be on all the time . . . they just kind of hover in one spot. I turn the pump off to give them some peace and they seem very happy them. Needless to say I am brand new at this and really want to make it work. Can anyone tell me if neon tetras are too little for this type of water movement?