Bigest mistake i ever made was when i was in 6th grade my moms friend gave us a 55g tank with a filter for a 20g tank so i got home set up everything and like a newbee whent to wal-mart got me 10 gold fish and some gravel so i got home got the hose filled the tank up and i dint put any water conditioner then i just put the goldfish within a week algea all over the glass so got a bucket and scoop the water out and with the fish still in their filled it right back up with the hose later on i found out i had everything wrong i cant belive my goldfish survide after that they grew about 10in each