When I change the water in my tank, if I have to do a big change for any reason (say, over 60%) is it better to leave the fish in the tank or to net them out? I have real plants which will droop, and if the fish hide in them while the water drains out I fear they might become trapped or frightened as the plants slump down on them. Obviously if I'm doing major tank stuff that needs a really low level I'd have to transfer them to another container.