Newbie Here Needs Some Help, feeds and water change.. Options

[CLYDEHAN19]

hi to all , just want to ask some questions regarding my ryukins and orandas.. ive been out for goldfish keeping for almost 2 years or so ,thats why im not updated on any new goldfish care or something..

here are my questions , thanks in advance guys..

1) i have a red and white ryukin ,about 5" , and another oranda in a 20gal tank , how much water change should i do and how often? both of them have an overhead top filter..

2)what are the sample foods that could help them attain their maximum sizes and coloration? (heard of egg yolks,green peas,home made paste foods,minced carrots?) and how often do i have to feed them ,2x a day?

3) how often should i give them bloodworms?

any other tips would be highly appreciated ..

im from manila philippines thanks and godbless..