Goldfish cannot be kept with other fish because they are extremely messy and can kill other fish. The eel and the loach should do fine together though.
But if you are planning to keep these two fish for a long time you will have to move them to a bigger tank because these fish grow much bigger...
although i am completely against bowls, betta fish and paradise fish both have the ability to go up to the surface of the water to get the air they need.
Because goldfish have so many things that need to be watched they are actually quite the unique fish to keep. As in if you have a goldfish, that goldfishes companions should be other gold fish. While they are small you can keep them with white cloud mountain minnows but once he goldfish grow big...