Hi Sandhya,

I do believe rainbow sharks are tropical. They require warmer water temperatures than goldfish – 72 to 82°F(22°C to 28°C), whereas most goldfish prefer temperatures around 65°F(18°C).

Hi Dilon,

The life cycles of some parasites will slow down in cooler temperatures, though that doesn’t mean your goldfish won’t get infected by these parasites. It will just take longer before you notice the infection, though the parasites will still be there. It will also take even longer to completely treat the parasites if you don’t first raise the water temperature to speed up the life cycle.

It is possible that some diseases have built resistance to warmer temperatures. Then again, some infections have also built resistance to cooler temperatures. Goldfish definitely prefer water temperatures around 65-70°F, and some goldfish might experience stress if left in very warm water temperatures for extended periods of time (longer than 3 – 4 months). This stress might make your goldfish vulnerable to disease.

Though the same would apply to goldfish left in very cool temperatures (below 55°F) for extended periods. In fact, goldfish will often hibernate in temperatures below 55°F. This allows pond fish to survive through winter months, though some fish hobbyists still like to bring their goldfish indoors if the weather gets very cold.

It’s better instead to create a balance. Preferably, avoid both very cool and very warm water temperatures if you’re keeping fancy goldfish in an aquarium. For pond fish, other measures are usually taken to ensure that the water doesn’t become unbearable and ice doesn’t completely cover the surface.

Usually though, if you’re maintaining healthy water conditions, feeding your goldfish a nutritious diet, and monitoring water parameters on a regular basis, you likely won’t run into problems. Infections usually only develop when goldfish are under stress. It’s very uncommon for healthy goldfish to get sick if you’re maintaining quality water conditions and taking safety precautions (like quarantining new fish).

Hi Jera – It definitely depends on the personalities of your fish. I’m glad your tropical mix has been working for you! Keep in mind though that guppies and goldfish both have different nutritional needs, so guppies might be better off with tropical food in their diet.

Hi Meg,

I wouldn’t recommend it, especially since many smaller tropical fish are small enough to fit a fully grown goldfish’s mouth! Goldfish are omnivores and while they can be sweet, I don’t think I’d ever trust them around my neon tetras. You’re better off keeping them separated.

At the time of this comment things were going well, mostly because my SAEs were smaller fry. I had to remove them once they got too large, they were nipping my Orandas tail fins and just harassing them. It did not work out. I treated the Orandas so they would not get an infection and bought a new tank for my SAEs and built a tropical community around them, With danios, and many live plants. It’s not a large tank but they love it. I’m sorry mine didn’t work. It had been, but I guess those slow fins were just too much of a temptation. It did take a while for them to turn though.