Fish cant breathe

Question
A friend gave me an aquarium I followed all directions but the fish are pushing their heads above the water like they can't breathe

Its been set up for 24 hrs its 40 gal

Answer
Hi Adam;

Make a water change of 25% until we can figure out what's going on. They may be lacking oxygen from being stressed so add an airstone hooked to an airpump too.

How many fish are there?
How big and what kind are they?
What kind of filter?
What is the water temperature?

You can join us on the freshwater fish forum at About.com to get even more information too;
http://forums.about.com/ab-freshaquaria/start

There is a wealth of information there. My member name is ChrisR62. See You There!

Followups welcome

At Your Service;
Chris Robbins