Ok..I certainly do NOT want to open up a can of worms here, but I just read the post that Sandy closed on tank size and the slightly heated debate on what is acceptable for goldfish in tanks. I am in a position where I can afford to upgrade my tank if I need to - tell me, guys, because I do trust you on this board - I have four fancies in a 46 gallon tank, they have been in it since September 05 (don't ask where they came from - two were in a six gallon and two were in a five gallon - I didn't know until I got on this board) - anyways, my one fantail, she is beautiful - and huge - probably six inches long - my other one is not more than three inches then - then I have what I thought were fantails, but since they've grown I have realized they are Ryukins - my mother in law bought all these fish for my daughters at Petsmart and they mixed Ryukins and fantails - anyways, these two Ryukins are about two inches at most - so - do I upgrade to a bigger tank? - is my tank too small? Is it possible that the size of my tank is the reason that only one of my fish truly grew huge? Each one of these fish, when they came to my family, were LESS than an inch, yet only the one fantail truly grew big - the others, not so big - is this because I stunted the others with a tank that really is not big enough?

Sorry for the long post, I just feel kind of worried about this - see, I thought how Sandy did, that the commons need the really large tanks, that they grow huge - I figured a 46 gallon is fine for fancies, now I am beginning to wonder - Maybe I should have what, a 75 gallon? If I got one now, would they grow larger? Are they doomed if I keep them in the 46 gallon? I am kind of confused here..sorry guys!

I think that with four fancy's in a 46 gal. tank,as long as you have excellent filtration,and perfect water params,you may be able to do it.It's so hard to say if the other's will grow like you want them too.Unfortunately,there are alot of different factors in this.Genetic's play a big part-also,the fish's first 165 days of life play a role-what it was fed-the water conditions it was in, etc.
For example,I received a tiny Blue Oranda a few years back.He came to me in poor health,but I managed to get him back to health .2 1/2 years later,although this fish seems to be doing well,it has grown very little.It is now only starting to form a wen,and it's weird because the fish looks like a baby compared to the rest.It has lived in good clean water,and been fed very well,and has still not grown much.
My real thoughts on Goldfish tanks,is that bigger tanks are always going to be better.With the correct filtration and such,they're easier to maintain,and your fish do have the most room that you can provide. I always say that if you can afford it,go as big as you can get.
If you weren't able to afford to upgrade,then I think 46 gal.would be enough as long as you kept up with weekly maintainance.You have said that you're in a position to upgrade though so personally,that's what I'd do.I just can't promise that anyone would have a sudden growth spurt-as I said,there are just too many factors in it all,so all you can do with no facts is guess or hope that they would grow.

I agree with Devs. Always buy the largest tank you can afford. More volume is better! In addition, we (goldfish keepers) are weak... we are always tempted to buy that beautiful fish staring at us in the pet store.