hi everyone. i just got new goldfish - four of them in a nice big aquarium with a filter. all died by morning.

then we got 9 more, we adjusted the temperature to 72 Fahrenheit - and we even let the filter run for around 6-8 hours before putting in the fish.

Already some are dying - just two hours since we bought them! I feel so guilty!! someone - please tell me what's wrong? Should i get an airstone?