Originally Posted by caitic10
Goldfish need 20 gallons per fish. So one goldfish, 20 gallons, two goldfish, 40 gallons. They may look small in the petstore but when healthy GROW!!!
Goldfish will die in heated water. And bettas need heated water...so bettas and goldfish should NEVER be kept together.
just to add to this .. goldfish roughly need 3-4g per inch of fish .. this is how u determine when to upgrade ur tank .. u can keep 1 baby goldfish in a 10g tank if he is only 1 inch big .. but as he grows out of his tank you HAVE to upgrade .. there's no if and or buts you HAVE to or else they will die and be very sick and lethargic if they don't have enough space .. also goldfish need need 2x the filtration per gallon of water .. so if u have a 10g tank .. u need a 20g filter ..
in adult stages fancy goldfish need 20g for the 1st fish .. 15 for each additional fancy goldfish
in adult stages common and comet goldfish need 30g for the 1st fish and 20g each additional fish
koi goldfish (which can grow to be huge .. 2feet at least to even more) .. should never be in a tank (even if it's 70-100g) ... they thrive in pond environments