Can Guppy Fish and Goldfish Live Together?

Whether you’re a newbie or an experienced pet fish owner, one thing’s for certain. Keeping different species in the same aquarium won’t be easy. It usually takes some time to decide which fish to buy and to research the new species. Then it takes even longer to set up your tank to accommodate all your fish.

For this reason, it’s best to choose compatible species. When all your fish thrive with the same water parameters and diet, this makes your job a lot easier!

Today, I’ll help you learn more about Guppies and Goldfish. This is a very common combo for aquarium owners. Both of these fish species are colorful, with big dorsal and tail fins. If you want a vibrant aquarium, these beautiful fish would help you achieve just that. So, let’s see. Can these fish coexist in harmony? How are they different, and how are they alike?

Can Guppies and Goldfish Share the Same Tank?

Luckily, guppies and goldfish are both peaceful and friendly. If you’ve wondered whether these two species can get along, the answer is a resounding “yes”! They shouldn’t have any reason to get aggressive or territorial, especially if there’s plenty of food to go around. Speaking of food, these fish will eat anything they can get into their mouth.

This becomes a problem if you have smaller guppies. You might have to separate them from the goldfish, otherwise, the goldfish will eat them. Most adult guppy fish should be too large to fit in a goldfish’s mouth, though. It’s also worth noting that both guppy and goldfish sizes might vary according to breed. Goldfish are larger than guppies, but there are also options for smaller-sized goldfish breeds, such as the Twisty Tail Goldfish (under 6 inches long), or the Butterfly Goldfish (up to 8 inches long).

Aquarium Setup

Guppies and Goldfish are a little different when it comes to their optimal living conditions. They don’t have the same requirements, so you’ll have to do some tweaking until you find the sweet spot. However, it’s not like these two species are complete opposites.

It should still be easy to strike the right balance between their space, temperature, and water requirements. So, let’s see what each of these two species needs, and how you can find a compromise between the two.

– Tank Size

This is where the difference between the humble guppy and the goldfish really shines. Guppies are easy to please, and one single fish requires no more than 2 gallons (7.5 liters) of water on average. In contrast to this, each goldfish requires at least 20 gallons (75.7 liters) of water to thrive. Keeping a goldfish in a smaller tank would lead to stunted growth.

As you can see, there’s a huge gap between the space requirements of these species. It’s obviously best to upgrade to a larger tank to fit all your fish. I wouldn’t worry about having too much space. A larger tank means slower accumulation of waste and smaller weekly water changes, so it’s a win-win. Your tank size will depend on the number of fish you have, and also on the ratio of guppy to goldfish you’re going to keep.

– Filtration

Goldfish are large and they produce more waste than guppies. Depending on how many goldfish you keep, you’ll have to complete larger or more frequent water changes. I’d say that in a mixed tank with guppies and goldfish, a filter is a must. Installing a good internal or external filter will help extend the time in between these changes and protect your fish from harmful ammonia and nitrates. But don’t think that installing one will save you from changing the water. You still need to do that every week

While goldfish can withstand higher levels of nitrates for longer, guppies are too small. Remember that the dose makes the poison, and relative to their body size, guppies might be getting higher doses of harmful waste by-products than goldfish would in the same conditions. Ammonia spikes are also dangerous and can cause burns or even death in fish. To keep both your guppies and goldfish healthy, you should do both— invest in a good biological filter as well as perform weekly water changes.

– Water pH

Guppy fish thrive in slightly acidic to slightly alkaline water, somewhere between a pH of 6.8-7.6, while goldfish can live in slightly acidic water with a pH of 6.0, as well as slightly alkaline water with a pH of 8.0. Sticking to a neutral pH of 7.0 should cover the needs of both guppies and goldfish.

Tap and bottled water are usually within the 6.5-7.5 range. You should still periodically test your water with a pH testing strip to make sure that the value is within these limits. Waste accumulation will lower the pH and turn the water acidic, so testing the water frequently will also help you discover the best time to freshen the tank.

– Water Temperature

The eternal struggle. Water temperature is crucial to the health of your fish. Too warm of a temperature, and your fish will die. Too cold of a temperature, and your fish will develop a weaker immune system…and die. The problem is that goldfish and guppies are quite different in this regard. While goldfish thrive in cooler water temperatures, around 40-78 °F (5-23 °C), guppies need warm water, usually around 72-82 °F (22-28 °C).

So, what do you do? You’ll have to keep a stable temperature that’s comfortable for both your guppies and goldfish. Not too warm, not too cold, perfectly balanced. In that case, I’d suggest aiming for a temperature of 70 °F (21 °C). This should work well for both species, without causing any negative long-term health effects.

– Maintenance

Besides filtration and water changes, you should also clean your tank and its contents regularly. Water isn’t the only thing that gets dirty. The walls of the aquarium, the substrate, and any decorative elements you keep inside the tank will also become contaminated.

Bacteria spreads quickly and it can get anywhere where there’s water. Changing the water without cleaning the tank isn’t going to completely eliminate the harmful bacteria and compounds lurking around.

You should vacuum your gravel at least once a week. Thoroughly washing the aquarium and its contents is also best done weekly, especially when completing larger water changes. Also, don’t forget to check and clean or change your filter whenever it gets too dirty. Last but not least, adding some live plants to your aquarium is another idea to keep the water fresh for longer.

Safe Plants for Guppies and Goldfish

Plants are a great addition to any aquarium. They enrich your pets’ environment and make things colorful. They act as natural water filters and the fish enjoy hiding between them and nibbling on them. But what kind of plants should you consider with a mixed guppy and goldfish tank? Goldfish are rather big and they’ll eat anything as long as it’s small enough to fit into their mouth.

It’s not dangerous for them to eat plants, but you might want to ensure that you’ll still have some greenery after these voracious eaters are done grazing.

In that case, consider some of the following plants; they grow super fast and are easy to maintain even for beginners: Duckweed, Water lettuce, Java fern, Water sprite, and Anubias. They all look great and they grow like weeds. They also contain lots of vitamins and minerals for your fish, which is a great added bonus!

Caring For Guppy Fry

Reproduction to guppies comes as easily as eating and sleeping. These fish can breed just about every month, and females can even give birth to 100 fry at a time. But not all the baby fish will make it. In a guppy-goldfish tank, the fry are under a double threat. Not only do guppies eat their newborns, but large goldfish will also try to snack on the little ones if given the chance.

If you want to save some of the baby fish, you must separate them from the main aquarium. You should either move them to a different tank or use a breeding box when the female guppies are ready to give birth. Keep your fry in a different tank for a few months before they grow big enough. If you don’t want any fry, you should only keep male fish, or keep your male and female fish separated.


Guppies and goldfish are an easy combo to keep. Except for a few minor tweaks, it shouldn’t be difficult to accommodate both of their needs. Just remember to provide enough space and keep the water temperature constant.

The water shouldn’t be too warm or too cold. Keep your water and tank clean, and install a good filtration system. That’s basically it. As long as you got these down, everything should run smoothly.

avatar Noah
I’m Noah, chief editor at VIVO Pets and the proud owner of a playful, energetic husky (Max). I’ve been a volunteer at Rex Animal Rescue for over 2 years. I love learning and writing about different animals that can be kept as pets. read more...

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