That bowl is DEFINITELY not enough space. If you have five goldfish, it would be better to have a 30 gallon tank, and even that may still be too small. Goldfish grow to be really big and can live for yeeaaars. If their going to the top of the water, that means they need more air in their water. You should purchase a sponge filter of some kind or a bubble curtain to add oxygen into the water.
You really should have researched them before you bought that many goldfish. If you are really serious in taking proper care of these goldfish, you are going to have to spend a lot more money. If you have any questions I can see what I can help you out with!
Five goldfish in a bowl.. Goldfish can grow very big. Even the fancy ones can get to 25+cm if kept properly (although it depends on the species, some stay a tad smaller, but still get very big). They don't belong in a bowl. It's probably a good idea to save up for a big tank or bring the fish to a pond. (I'm not sure where you live, if it's really cold you have to wait until spring).
Do you have a filter in your bowl? If not, buy a filter in a pet store. In the filter bacteria lives that convert the waste of the fish (ammonia) to nitrate. Plants absorb nitrate. If your filter doesn't fit in a bowl, go buy a watertight plastic box. Like these: [link] They are pretty cheap and it'll give your fish much more space.
In my goldfish tank, I measure a minimum of 50 liters (about 13 gallon) per fish. That seems much for a small fish, but small fish need space to grow. Also, goldfish produce a lot of waste and that's why they need so much space. Another thing is that goldfish produce 'growth hormone'. When they grow, they produce growth hormones, and it will build up in the water. When there's too much of this hormone in the water, the fish will stunt. That means that the body of the fish stops growing, but their fins, eyes and organs keep growing. That way, stunting can cause very serious damage to the fish.
For now on, do a 50% water change every day. Make sure that the water is the same temperature as the water in the tank (goldfish don't like temperature changes). That can already help a lot.
Here are some sites that can help you: [link] Goldfish and Aquarium Board. A lot of articles about how to keep goldfish the proper way, diseases and more stuff. [link] Kokosgoldfish, a forum about goldfish. It's very informative, and there's a lot of information too. [link] A very informative site.
I hope I've helped you with this and your goldfish get happy and healthy