jeep8rus said:I know the goldfish is a coldwater fish..............I'll take suggestions for other coldwater fish that are colorful.
SoCalSunset said:Hi Jeep8rus! Welcome to AC, I hope you have a great time participating in the learning that takes place here.
I disagree with the statement that goldfish and bettas are incompatible due to temperature, but I do agree that they are incompatible, because an adult goldfish can and will eat a betta, or just kill it for no aparant reason. Goldfish are not 'coldwater' fish specifically, they are temperate water fish.This means that they can survive in coldwater (even if it's slightly frozen on the surface), and also tropical temperatures (as long as it's a gradual change such as the changing of seasons).
I have a blue goldfish in my tropical community (180g). I also know that there are others on these boards that keep goldfish in their tropical communities. Glimmering Goldfish suggests that the aquarium temp. for goldfish be kept around 74F.
There are a lot of public and private ponds here in SoCal that have goldfish and koi in them, and during the summer, the water reaches 85F easily. But the splash from small fountains or waterfalls aerates the water properly.
Basically, goldfish can thrive in warm water, but they will need more oxygen. As long as you have an extra air stone connected to an air pump, or there is a lot of oxygen injected by your filters outlet, you should be fine. However, your goldfish will need a much larger tank than the 20g. Even feeder goldfish grow very large (around 24" easily).
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