are there any other types of cold water fish to add to goldfish tank?

The most common coldwater fish is the goldfish, followed closely by it's larger counterpart, the Koi. However there are many other interesting fish that do not require a heated tank. Many coldwater fish are large enough that are only suitable for ponds. Since you are planning to set up an aquarium, I've put together a list of fish that are small to medium in size.

Barbs - Several readily available species of Barbs are tolerant of temperatures into the mid sixties, or even lower. All are easy to care for, and are suitable for a community aquarium. They include: the Gold Barb (Barbus schuberti), the Green Barb (Barbus schuberti), the Rosy Barb (Barbus conchonius), and the Two Spot Barb (Barbus ticto).

Bloodfin Tetra - Both the standard Bloodfin (Aphyocharax anisitsi), and the False Bloodfin (Aphyocharax dentatus) tolerate temperatures as low as the mid sixties. Bloodfins are offered in many pet shops, are easy to care for, and are quite hardy. They are active top dwellers and are best kept in schools.

Buenos Aires Tetra (Hemigrammus caudovittatus) - Easily found for sale, they will tolerate temperatures into the mid sixties. Standard varieties, as well as albino variants can be found. Like the Bloodfins, they are undemanding and easy to care for. They are suitable for a community tank, but will eat live plants voraciously.

Croaking Tetra (Coelurichthys microlepis) - Not often found for sale, they are an attractive fish that is worth shopping around for. Like other coldwater tetras, they are easy to care for and are suitable for community tanks.

Guppy (Poecilia reticulata) - As readily available as any fish, there are many attractive variations of this popular fish.

Hillstream Loaches - Although they are not often seen in pet shops, some species can be found for sale from time to time. Not all of them prefer cool temperatures, but most will tolerate temps that fall into the mid to upper sixties.

get a golden dojo loach they are cold water 55-75 degrees REALLY cold water but they need to be bought in groups of 3 or more to be happy i was thinking of doing that with my fish dojos are really fun because they like to bury there self with just there heads sticking out of the rocks they are super bold and rub against your hand when your cleaning the tank plus they will eat anything from blood worms to flake food they are a great a addition ps.they get to be 9-10 inches long live up to 15 yrs (like goldfish)

White cloud mountain minnows (I forget their Biological name) are a pretty little little fish which generally grow to be no more than an inch and a half in length so a bunch of these guys swimming around with your larger sized goldfish can create a very nice effect hope that helps!

the only other fish you could put in is a white cloud mountain minnow.

here is a picture of one....

http://upload.wikimedia.org/wikipedia/commons/1/18...

Plecos actually shout NOT be kept with goldfish. The reason is goldfish prefer cold water and will not thrive in warm water unlike the plecostomus which should be kept only in large tropical tanks.

Also one goldfish required 20 gallons and each additional needs 10.

-fishable12

What size tank do you have? We could use that information to make better suggestions for you.

catfish (they grow huuuuge!! mine was like 8 inches long!! i got him like maybe 3 inches but they just keep growing) theyre really cool though

well there are koi and there are mollies. mollies are both freshwater and saltwater.