Keeping goldfish and cory catfish in the same tank is something many aquarists think about. Unfortunately, it’s not as easy as many people claim. There’s no one simple answer to this, but we can take a look at the various factors that decide whether you can keep them together.
Cory catfish and goldfish don’t make super tank mates, but in some cases, it is possible to keep them together. Since goldfish can swallow cory catfish, only big Corydoras species (>2.5 inches) should be kept that can live in lower temperatures.
The most important thing to consider is the size of the cory catfish. Goldfish will try to eat or swallow cory catfish that fit in their mouth, but their spines will make it a nasty ride for the goldfish.
This is the main defense mechanism of cory catfish, so they will use them. Also, they’re venomous making them extra harmful if eaten! Goldfish will choke if their spines get stuck in their mouth.
Lastly, cory catfish are great tank mates because they’re very peaceful. Overall, aggressive tank mates are a no-go (such as barbs or cichlids), but cory catfish are calm and will never harm other fish.
If you’re interested, I’ve also written an entire article on the best tank mates for cory catfish. Click the link to read it.
Tips keep cory catfish and goldfish together
Although cory catfish and goldfish are compatible character-wise, you should take into account some things to keep them together successfully.
Both fish also come from totally different habitats, making them subject to different water parameters and conditions.
Tank size - goldfish and cory catfish
As you probably know, a small group of goldfish should be housed in a pretty big (>40 gallons) tank. This might even have to be upgraded down the road since they grow pretty big.
On the other hand, cory catfish require a tank of at least 20 gallons because they have to be kept in groups.
However, as we have discussed above, only large Corydoras species are a good fit to live with goldfish. For bigger species, the tank size has to be increased to 30-40 gallons.
Conclusion: tank-size-wise both species tend to have similar requirements.
Filtration - goldfish and cory catfish
As you might know, cory catfish don’t need very strong filtration. They do well in most setups, you can even use a sponge filter in a lot of cases.
Goldfish on the other hand are heavy polluters. They produce a lot of bioloads, making a strong internal or external filter a must. Preferably a filter that cycles 6-10x the volume an hour. This will ensure the water quality stays high.
Another thing to consider is the number of water changes you will have to do. The same story again: cory catfish tend to do well on an easier schedule, while goldfish will need a lot of water changes.
Conclusion: ensure that strong filtration is present and perform regular water changes because goldfish need this to thrive.
Food - goldfish and cory catfish
Overall, goldfish tend to fit whatever fits in their mouth. They do best on a diet that consists of mainly plant-based fiber-rich materials since that’s what they tend to eat in the wild. You can supplement this diet with some protein-based foods or insects which they will happily eat. I recommend Hikari Fancy Goldfish.
PS: goldfish are also great algae-eaters!
Cory catfish are in fact quite the opposite…
They need a high-protein (so meat-based) diet to thrive and the food that you typically give to goldfish should be avoided as much as possible. Great foods for cory catfish are Viformo pellets and API Bottom Feeder Pellets.
Conclusion: both species should be fed their own specific diet.
Temperature when keeping goldfish and cory catfish together
Goldfish prefer a temperature that doesn’t elevate above 70°F. Some fancy types prefer to live in higher temperatures, up until around 76°F. Overall though, lower temperatures are better.
Some cory catfish also do well in these lower temperatures. Examples of species are Peppered Cory Catfish (59°F) and False Julii Cory Catfish (>60°F). If you’re interested in knowing more about the best temperature for cory catfish, you can read this article.
Goldfish and cory catfish have similar preferences in terms of substrate. Cory catfish are more flexible than cory catfish, though since they don’t really hang out much in the bottom layer. I’d recommend to go with sand or a round gravel.
Avoid bigger pebbles, because goldfish can choke in these. Cory catfish also will have a hard time freely digging.
Best cory catfish types to keep with goldfish
As we discussed above, the best species of Corydoras are pretty big. They should be at least 2.5-3 inches, so that goldfish will not swallow them.
I’ve added three species that meet these criteria. Certainly stay away from small Corydoras species, like panda cory catfish and pygmy cory catfish. These will definitely cause problems.
Second off, only put full-grown cory catfish with goldfish. This will ensure the goldfish can’t eat the cory catfish and die from the spines getting stuck in their mouth.
If you want to know more about cory catfish and their size, read our full Cory Catfish Size Guide.
Alright… Technically, this isn’t a Corydoras species. However, they are very similar and are too good of a fit to not be put on this list.
It’s one of the biggest “Corydoras” species and it likes colder water (>60°F)! This makes it able to live with all species of goldfish, even the ones that prefer lower temperatures.
Sterbai cory catfish
Corydoras sterbai is one of the bigger species of Corydoras, making them a good fit to live with goldfish.
They do however prefer to live in warmer water, so they can only live with fancy types that prefer this, too.
This last one is also technically not a Corydoras, but it is great to keep with goldfish. I got this tip from Aquarium Co-Op, and I love it!
It’s also a very big species, but it does prefer a heated tank, making it only able to live with fancier types of goldfish.
Best goldfish types to keep with cory catfish
I’ve included some of the smaller goldfish types. These are usually a better choice to keep with cory catfish, because of the outlined reasons. Of course, there are many other varieties that would be great!
Fantail goldfish are a fairly easy species of goldfish. They can live in higher temperatures, so a heater is certainly a good pick. This makes them able to live with almost all bigger cory catfish species.
This is certainly one of the easiest to recognize goldfish types. The brain-like structure on their head makes them almost look like an alien!
Another type that does fine in somewhat warmer water. A heater is thus recommended!
Butterfly goldfish can come in many varieties, such as lion heads or telescopic eyes.
They come in many forms, colors and variations making them very interesting to look at.
Summary: can cory catfish and goldfish live together?
Cory catfish and goldfish don’t make perfect tank mates, because they have somewhat different preferences in terms of diet, tank size, and temperature.
However, with some adjustments both fish can live together successfully, here are the main ideas:
- Buy a large, >30g tank where the cory catfish can grow big.
- Look at the temperature, some species of goldfish like colder water, the same goes for cory catfish
- Goldfish prefer a plant-based diet, while cory catfish need protein-based foods.
My three favorite cory catfish to keep with goldfish are Scleromystax barbatus, Corydoras sterbai, and Brochis Multiradiatus.
So, I hope you learned a lot from this article. Feel free to read our other guides such as cory catfish and shrimp or cory catfish and betta fish, so you can build your dream tank! Also, leave a comment if you have any questions.