Two of the most popular aquarium pet fish species are the Betta and the Goldfish. These are both very attractive and many beginner fish keepers will probably go to the local fish store and purchase these and put them together in one tank.
That isn’t really such a good idea.
Read further to know the reasons a Betta and a Goldfish can’t be long-term tank mates.
Different preferred temperature range
Betta fish are tropical fish that thrive in the tropical temperature range. They come from Thailand where the tropical climate has a freshwater temperature ranging from 76 to 82 degrees Fahrenheit or 24 to 28 degrees Celsius.
Goldfish thrive in the cooler temperature range of 68 to 74 degrees Fahrenheit or 20 to 23 degrees Celsius. Comets and shubunkins goldfish types should be kept between 60 to 70 degrees Fahrenheit or 15 to 21 degrees Celsius.
They may live in a median temperature as suggested by other experienced fishkeepers but this is really not good in the long run. The fish will be easily stressed living at the far ends of the temperature ranges at which they thrive.
This big difference in water temperature preference of each fish can lead to problems for Bettas. Betta fish will be lethargic because of slow metabolism.
Bettas will be more prone to disease when the temperature goes below 74 degrees Fahrenheit or 23 degrees Celsius. Diseases such as fin rot, ich, and digestive disorders may strike.
Bettas prefer warmer temperatures compared to goldfish which prefer cooler temperatures.
A goldfish that is put in a warmer tank will have a faster metabolism which will reduce its lifespan. This will also make the goldfish’s digestion faster which makes it poop more. This brings us to the next point to consider.
Goldfish poop a lot and Bettas like clean water
Goldfish forage continuously and they poop a lot more compared to a Betta. This will mean that the water has a higher chance of getting dirty quickly especially if they are put in a small tank. A sudden increase in ammonia called ammonia spikes are harmful to fish.
These two species are hardy fish but Bettas are sensitive to increased ammonia. Goldfish constantly pooping will require more frequent cleaning which your Betta doesn’t like. Risking ammonia spikes is worse than keeping the tank clean.
Bettas are very territorial and they don’t like frequent changes in their environment. Also, constant water changes can create sudden fluctuation in water parameters which can affect you Betta.
Preferred water flow and water current strength are also different
A Goldfish’s tank usually has a strong filtration system with a powerful flow to prevent the poop from staying too long on the bottom of the substrate. This powerful flow is tolerated by Goldfish but Bettas dislike strong flow.
Male Betta fish usually have long flowing fins and tails compared to their body size. This will cause them to be whipped around by the current and will be constantly exhausted. This may lead to more stress, exhaustion, and even death of the Betta.
A weaker filter such as a sponge filter may be suitable for a Betta but is insufficient for a Goldfish. The Betta will appreciate the gentle flow from a sponge filter but this will not be enough to clean up the Goldfish’s poop.
What about fish behavior such as aggression?
The aggression of bettas is well known especially male Betta fish. These fish are highly territorial and will constantly want to keep other fish out. Goldfish however can just outgrow a Betta.
The Goldfish has a tendency to forage all over the fish tank making it very stressful for your Betta. The Betta will stay away from a big Goldfish but its constant intrusion into the Betta territory will stress your Betta out.
If the Goldfish is still small and has flowing fins then it can be a target of betta’s aggression. A Betta has a powerful bite and can tear out the fins of a Goldfish. These torn areas can be a source of infection and could lead to death.
Goldfish like to eat a lot and they may be fin nippers when they see the fins of Bettas. Fin nipping can injure your Betta and be a source of infection. This constant fin nipping from a Goldfish may also kill a Betta. A Goldfish may really grow a lot bigger and may make a meal out of a small Betta.
What about their preferred habitat?
Betta fish will love a planted tank. Their natural habitat has plenty of lush vegetation where they can hide and feel safe. The plants also are not a food source for Betta fish which makes them a great candidate to live in a planted tank.
The beauty of a betta fish can complement the beauty of an aquascape. Many aquatic plant enthusiasts prefer having a Betta as an inhabitant because it can live alone and will not mess up the fish tank.
Goldfish have the reputation of uprooting plants and this will surely irritate a fishkeeper who wants a beautiful planted tank. It may also make a meal out of softer and more delicate leaves of certain aquatic plants.
This makes the Goldfish a very poor choice as an inhabitant of a meticulously arranged planted tank.
How about tank size?
The recommended minimum tank size for a Betta fish is 5 gallons while the minimum for a Goldfish is 20 gallons. Putting a Goldfish with a Betta in a 5-gallon tank will surely make the water dirty fast. Ammonia will increase and cause harm to the fish. This will also not allow your Betta a space of its own.
Putting a Betta in a 20 Gallon tank of a Goldfish will also not be a good idea. If the tank was set up for the Goldfish then it probably isn’t suited for a Betta. These tanks usually have fewer hiding spots, fewer plants, more flow, and stronger current.
Can they eat the same food?
Betta fish are carnivores and prefer a meat-based diet high in protein. Goldfish are omnivores and will steal the Betta’s food. The Betta fish are usually calm while the Goldfish are fast.
The Goldfish will eat most of the food during feeding time making the Betta probably get less food.
Bettas are naturally insectivores and they need plenty of protein in their diet to stay happy and healthy. Plant-based food can be fed to a Goldfish but not suitable for a Betta.
Betta fish shouldn’t be fed with Goldfish food pellets because these may contain a higher amount of carbohydrates. This may cause bloat and constipation to your Betta fish.
Will they eat each other?
A Goldfish depending on the species can grow to about 12 inches long. This size will make it a threat to the Betta. Remember that in the fish world if it can fit into a fish’s mouth then it can become food. You might be surprised to find out one day that your Betta has been the food of the bigger fish.
How about during an emergency in the fish room?
Let’s say your betta fish tank broke and water started leaking out. Is it ok to let it stay in your Goldfish tank for a while as you buy a new tank? It may be better to just use a food-safe plastic tub as a temporary home for your Betta fish. Transfer the heater to provide the correct temperature. Transfer the filter to preserve the beneficial bacteria colony in the filter media.
This is also one reason it is best to have a back-up tank even if it’s just 2.5 to 3 gallons. This will give your Betta a temporary home while you repair or get a new tank. If something happens to your Goldfish tank then a goldfish can also enjoy a back-up tank or tub so it needs not to intrude into your Betta fish tank.
What if I don’t have any containers?
If you really don’t have a back-up tank then you can put them together for a few days. Be sure to observe their behavior and prevent ammonia spikes from happening.
Set the temperature to the lower range suitable for a Betta fish. The goldfish will tolerate a few days of higher temperatures. Good husbandry practices will be of important use and this may buy you some time while you are handling the problem.
There are a lot of things to consider when choosing the correct tank mates, especially for Bettas. So can you put a Betta fish with a Goldfish? If it is an emergency then you can do so for a short while
With all things considered and as discussed above the quick answer would be ‘No’.