Tropical freshwater fish and a goldfish

Question
We have a freshwater aquarium, which normally is at a temperature of 26-28 degrees according to the thermometer on the outside of the glass.  It has guppies, corries, platies, etc ...

We have been given a goldfish, with bowl etc, but the water has already gone cloudy (in 2 days).  I would like to put him in the aquarium with its filters etc, but don't want to kill it by the water being too warm, or have him eat my other fish (would like hime to eat the babies though as they are always too many of them!), or him not to suit the tropical fish food ...  What do you think?

Thank you.

Answer
Well, I assume the 26-28 is celsius? If so that is about 80 degrees F? Do you have an ajustable heater? If so, you could lower it to about 78 and that would be better for the goldfish. You can add goldfish to tropical tanks but keep in mind they are more active in coldwater and tend to do better. as for eating the fish, it depends really. How big is the goldfish, if he is big he might eat the fish if he is small, probably he wont mess with any. He could go for the babies, thinking they are food, but it would not be a prey thing, he would acidently eat them. He would do better on goldfish food but I would imagine they have pretty much the same basics. You could add half and half of each food. It is also normal for the bowl to get dirty so fast, goldfish are super dirty fish and produce a large amount of waste so it clouds the water. And not having a filter just lets the stuff sit there and gather up. One other thing about adding him to the tropical tank, he will make it more dirty requiring more cleaning. You should do weekly 10% water changes and syphon monthly to every 6 weeks. While you probably should do this anyways, with the goldfish it is more or a must than recommendation. But of course it can be done. But of course keep in mind, goldfish are coldwater fish and may or may not do well in warmer water. It all depends on the fish. Fish are as unique in terms of personality as people and surprisingly some like warmer water and some dont. I hope I have helped you. Let me know if you need more information.
                                            Rachel A.