how do i change the water my fry are two weeks some are older then the other i have them in an tubble ware with filter what do i do???? B)

and when do i start on feed them flake food there 2 weeks old the older ones are 4 weeks old and turning white under neath them is that normal??

http://www.kokosgoldfish.com/forum/index.php?showtopic=21941

Do you have any that i might be able to have by any chance?
Dean