I have no clue on goldfish/koi , I have an aquarium with goldfish and koi  and have recently discovered that there are new additions 4 of them HOW? and could someone tell me why fish would lay on the bottom do they sleep, its mainly the bigger ones. Do they have goldfish/koi book for dummies? Cause that's me lol any info would be helpful.

The don't alway do it because of stress  My Clementine actually sleeps on the bottom of her tank.

Now if I was you I would get those koi out of that tank, Koi need an absurd amount of space which you really could not provide in a tank. They will become aggressive and may attack/kill your goldfish. Are you able to givete koi away or build a lovely big pond for them?

Here are some links to get you started on goldfish care
(Link is not visible to guests. Please register to view.) Feeding
(Link is not visible to guests. Please register to view.) The Nitrogn cycle
(Link is not visible to guests. Please register to view.) Tank requirements

Now they are just some links from this forum, keep having a look around and you'll find plenty more info here and all over the internet.

There is actually a goldfish book for dummies Go have a look at your local library or book store and I bet you will find tons of books whih are incredibly helpful to have and will answer alot of your questions. This would be one of the best things you could do as long as you get a reliable book, there is even a post on this forum about goldfish books.

Any other questions, just ask us I would like to know how big your tank is and how many fish you have in there? Do you know about the nitrogen cycle? Do you test your water? What is your weekly maintenance of the tank?