Just wondering if it would be okay or a bad idea to add new fish to my tank at night? I work in London but live down in the country and travel by train, am aiming to pick up some new fish from the aquatic design center on friday but would get back in the evening when the light has gone off on my tank, I am currently doing a blackout on the tank to get rid of a bit of BGA until saturday morning, so would be adding them when it is fully dark for the light to come on in the morning. 70L tank with 8 tetra and 2 guppies. What do people think? Thanks.