I have a common alone in a tank and he looks lonely. Is there a fish that can live in cold water with him besides a goldie that is not as big? Something that can live in cold water, any fish. Something commonly found in petstores. Like catfish or something. Any ideas. My common is small now and won't eat the fish he just wants a friend.

It really depends on how big the tank is and what temp it's being kept at.

how big is the tank?
you could have rosy reds or white head minnows or a apple snail

I've kept White Cloud Mountain Minnows in with my Goldfish over the years with great success. They are small and eat very little.

Can you put catfish in with golfish Sorry that stood out cause im trying my hardest to read up on catfish but the info isnt out there on how to house them or care for them, what else can they go with etc...

We was looking into getting a catfish but if I dont know nothing about them I cant lol.

some types of pleco can be kept with goldies (not common plecos though) but i am under the impression that the two different types of fish may well just ignore each other.

White cloud minnows or something similar is a good idea, although keep an eye on them as they can be nippy towards goldies tails, and also goldfish can try to eat them if they are small and can fit in their mouth.

Depending on the size of your tank, a couple of weather loaches, could be a good addition. They are very amusing fish and get on well with goldfish.

I also have hillstream loaches in with goldfish, although they require an environment suited to them, i.e., a lot of aeration, current, and most importantly, a tank that has a good supply of green algae. They like a rocky decor, as well. Also, they like to be kept in a small group, of at least 3.

Koi is also a coldwater fish~

Unfortunately Koi are not suitable for tanks.

Like touchofsky I have also kept hillstream loachs they prefer groups of 5 tho you can keep 3.They also prefer slightly acidic water prefered pH 6.8 max They prefer really cold water 64 - 74 F preferable temp being 64 F They will tolerate higher temps but temp must be increased over a period of around 10 days.They eat all kinds of food bloodworm,brine shrimp ,daphnia,flakes.From personal experience I found mine ate very little algae and would shoot out of hiding to eat the fish food at feeding time.They are very gentle fish and will not defend themselves if attacked.

Heres a link on them.I love the little guys

http://animal-world.com/encyclo/fresh/Hill...streamLoach.php

Blue,
Your advice is very sound, although my hillstream loaches have done very well at ph 7.8-8.0, with alkaline water. My hillstreams do graze on the algae covered rocks, although I wouldn't use them as "algae eaters", as most people think of those fish. When I first got them several years ago, they didn't eat any prepared food, but now love ProGold pellets and wiggle and squirm like crazy when they get on a pellet