New Tank

i have bought another new tank 24x15x12 for my gold fish which i have had for about 2 1/2 years one is about 5" the other about 4" should i leave them on there own in the new tank or can i put some other cold water fish in with them? if so wot should i put in with them i would like to put something else than gold fish in.

you could try paradise fish, they are coldwater and very pretty, but im not 100% sure they can go with goldfish, ive never seen them with goldfish.
another fish is a hillstream loach, they look like flat fish, and are really good at cleaning

hope ive helped a tad

i have 2 paradise fish in with my goldfish.........havent really noticed any aggro

Leave it at the two goldfish, it is only just big enough.

wot bout hill stream loaches could i put them in it to keep the algae down?

No tank unless in extreme circumstances will just have algae in it because it decided to grow. Uually in new tanks algae will grow because the vitamin/mineral levels are varied due to the ammonia nitrIte and nitrAte levels going bonkers. In established tanks with correct light levels and plants if need be you should not encounter algae in your tanks. Furthermore Hillstream Loaches need a fast flowing highy oxygenated tank with some flat rocks for them to clamp onto, i do not think these conditions will be good for your goldfish.

Hope To Help
Bret