OT - Anyone know anything about aquariums?

I would call myself an aspiring aquarist, but more likely is aspiring fish killer. :frowning: Some friends gave me a 20-gallon setup that is lovely and convinced me it’s way easier to keep the fish happy and healthy in a larger tank. I just put the first little guys in there and they’re just hanging out at the bottom looking like they wish they were dead. Is this normal? Anyone know? I know this is REALLY OT, but I don’t want them to die!