I have a tall 20 gallon and a long 20 gall, and I Have some 6 in goldies, and some 2 in goldies, which fish should go where?

I would put the larger goldies in the long tank and the smaller goldies in the 20 gallon high.

i agree with br553. the bigger ones should go in the long.

K so are long tanks better than tall ones?

:bingo

Because goldfish are long fish and like to swim from side to side the longer the tank the better off they are. I always like to say that high tanks are normally better for tropical fish rather than the goldfish.

Thanks Koko! I guess that means when I have a custom made, it should be long and not tall!

Plus the longer one has a bigger surface area than the tall one. Bigger surface area = better oxygen exchange. Which is very important for bigger fish, they need more oxygen than smaller ones.