one fish died not sure what to do with the other

Question
hi i bought 2 goldfish about 2 years ago now one was a yellowy goldfish and the other more orange. as the fish began to grow the orange one got bigger than the yellow one which didnt seem to be growing as fast. last week the filter broke but the fish seemed fine and swimming around happily as usual, but 2day i noticed my smaller yellow fish had died and i dont know why. the orange fish is now close to the bottom of the tank swimming very slowly, it almost seems sad. there are some very small blue dots on the glass of the tank but i thought it was just bacteria. i now dont know what to do with the other fish because i dont want to buy any more to give it company due to the upset of my little brother when this one died. my boyfriend does however have a pond with a few fish in it 2 of which are goldfish. should i put my fish in there, im a bit worried it will be too cold as this fish has only ever been a house fish. also if it does have any disease which i never noticed in my other fish as its death was quite sudden, i dont want it to infect my boyfriends pond fish. help what is best for my fish?

Answer
Hi Becky,
Thanx for your question.  I think your goldfish died of natural causes unless someone put something in the tank in which case the other fish would have died too.  I don't know what the blue dots are.  I'm not an aquarist (indoor fish fanciest).  I would not recommend taking fish that are used to the warmth of indoors and exposing them to the cooler/colder/more freezing temps outdoors in most parts of the USA.  Just wait a few weeks and see what happens with the remaining fish.  If it dies, clean the whole tank out and start over.  I hope this helps.  
Tom