A friend of mine's goldfish and koi have just layed eggs, he removed them from the pond and placed them in a tank, does anyone know how long until the get to a good size(6-12''?

I'm not as familiar with the growth rate of carp and goldfish as much as I am with the Oscars, however, I can tell you that they will grow quicker in a heated environment. Normally carp and goldfish are kept in cold water and environment. During the colder months, they don't feed much. So in a heated environment, they will eat all year round. Personally, I think keeping koi carp isn't a good idea unless it's absolutely huge, remember koi carp can grow in excess of thirty pounds. A rough guess to how long they would take to how long they would take to reach 12 inches would be more than a year. Also depends what sort of goldfish you've got. If it's a golden orf then they can grow to over 12 inches, around 18 inches. Once again, it's going to take quite a while. Both these fish produce absolutely tons of waste, more than Oscars.

Yep, I've kept them before. He has four varieties of goldfish(orandas, shubinkans, lion heads, and black moor,) and two varieties of koi(butterfly and normal). I may get a water garden, so I was U know, interested.

if hes kept koi and gold fish together then i doubt any will be pure koi?he will have cross breeds and 99% will just turn out a bronzie colour and it will also make them slower growers than koi!if they were koi and kept heated then you could grow a koi to 12" in a year but it does all depend on the ginetics of the ones that have breed.i used to keep koi in a 30 ' x 35 ' pond that was heated

No, the ponds not heated. Yeah, he has both koi and goldfish, he recently got some awesome bizarre colored goldfish(and no, luckily their not dyed).