I've had my aquarium for about a week and I've noticed that during the day when the light is on the fish just stay in the current generated by the air pump, but at night when I turn the light off I can see them swim around by the light of the heater. This is the only time I feed them because its the only time they eat, during the day they just let the food sink to the bottom. Will they get used to light eventually or will they stay like this? (they are 2 ghost catfish in a 10 gallon tank)