shubukin behavior

Question
I have 4 fish in a 10 gallon tank, 2 are gold fish probably 2 inches in length, the other 2 are shubukins and they are about 1 inch in length give or take.. plus their fins. 1 of them has been acting weird, i have a fake plant in the corner of the tank and it seems to go into the corner of the tank and go face first down into the corner and sits there, no movement at all just sits face first in the corner of the tank bottoms up. every once in a while it'll move a little or come out when i feed them, but it takes a while. my gold fish are male and my shubukins im unaware of their sex. please let me know of what the problem might be asap. thanks, shannon

Answer
Hi Shannon;

Change 25% of the water to start helping the sick fish feel better while you give me the following info so we can work together in figuring this out;

How long has the tank been set up?
What kind of filter system? How often is it cleaned?
How often are water changes made? How much water is replaced every time?
Does the sick fish look as if it has a bloated belly?
Does he seem to have trouble staying upright when he does come out?
Do the other fish bully him at all?

That little ten gallon is not going to be big enough for all four of those goldfish as they grow to their adult size of 6 to 8 inches. (Shibunkins are goldfish too, just a fancier variety.) Here is more on goldfish and their needs;

http://www.firsttankguide.net/goldfish.php

At Your Service;
Chris Robbins