Goldfish with tropical fish like, say, neons? Wouldn't neons, and any tropical fish this size, be too small for goldfish? I think it's possible that goldfish would eat neons, eventually! But ... I may be wrong. However ... this is what I think.
Goldfish are actually temperate water fish.
They really need to stay at 72F and below.
As well, any fish is at risk when housed with fish that are large enough that the smaller fish fits within the mouth of the larger fish.
I have had two fantail goldfish in my 55 gallon tank for about six months. They live with neons, rasboras, danios, swordtails, etc. I keep my tank at at least 80 degrees and they seem to be fine, except for the fact that they are getting big! I never see either one bullying the smaller fish. Eventually I'd like to get a tank for just the two of them. Mostly because I'd like to add more fish to my 55 gallon tank but I don't want to overcrowd. So, for now, they'll keep living happily together.
That's cool, I wish my goldfish (may they rest in peace ) would survive that well! But that is kind of odd because I have always heard that goldfish would not be happy or healthy in a tropical tank. Somebody said that putting one in a tropical tank would be like putting a canadian in the middle of a desert for the rest of their life. Maybe your goldfish are a different kind of goldfish? Hmmm. Well good luck with all your fish!
Yes, goldfish could live with much smaller fish like neons IF goldfish are raised from babies with these small fish - so that they get used to the small fish. But I think if you put adult goldfish (who never lived with small fish before) into a tank with small fish, there is a good chance they could eat the smaller fish. I have 2 angelfish who were raised since babies with 12 neons. And they never bothered my neons because they're used to them. I think it would be much different if I put adult angels with neons!
I know it is :-[ but it wasn't very nice to watch - some of the tadpoles were too big and the goldfish would gobble one up and it was give the goldfish all **** so it would spit the whole tadpole out again! :-X