+*The tank size is 1 gallon..it is a bowl without any hookups to it... We change the water every week..We add something to it because we have city water ..it is something a goldfish expert gave us. There are 2 fish in it that are about two thumbs size..There is no strange behavior. But there is something on one of its noses thats white about half a fingernail in size...What is it? I feed theme TetraFin Goldfish Flakes...about 2/7 of paper laid out?? WHaT is IT? Signed, ConFuZed