Are betta and  goldfish suitable tank mates?

Betta fish and goldfish are beautiful fish. Taking care of them is quite easy. Hence, they are among aquarists’ favorite aquatic pets. Sometimes we would like to have an awesome community tank and we might think: Why not put my betta fish and my goldfish in the same tank? Can they share the same tank? In this post, we will discuss the different water parameters, dietary needs, and environmental preferences of both betta fish and goldfish exposing the reasons why it is better for them to be separated.

Are betta and  goldfish suitable tank mates?

Well, if you consider the best interest of your fish, then the answer is no. Betta fish and goldfish cannot share the same tank. 

Betta fish and goldfish have different requirements to thrive. Although betta fish and goldfish are beautiful, and the idea of having them in the same tank is enticing, they cannot share the same aquarium.

Betta fish overview

Betta fish, also known as Siamese fighting fish or Fighting fish (Betta splendens), is native to Cambodia, Vietnam, Laos, Myanmar, Malaysia, Indonesia, and Thailand. They usually live in rice paddies, canals and floodways, and marshes. These fish are territorial and can attack each other, as well as other fishes when in the same aquarium. A long time ago, betta fish were used for fighting matches as means of gambling.

Betta fish appearance

Adult betta fish grow to a length of 2.4 to 3.1 inches (6 to 8 cm). Betta fish have been selectively bred and they can be found in beautiful shades of yellow, red, turquoise, marble, copper, and even multicolor. They also have different types of fins: veiltail, crowntail, elephant tail, rosetail, plakat, double-tail, among others. If the betta fish is well taken care of, they can live up to 5 years. 

Betta fish behavior

In their tank, betta fish can attack other fish when they feel that their territory is threatened. So, when having bettas you must make sure that they have plenty of vegetation, hiding spots, and at least 10-gallon (45 L) per fish. 

During breeding, male fighting fish build a bubble nest to attract potential females for breeding. After the eggs are hatched, the parents do not look after their fry.

Betta fish diet

Betta fish are carnivorous. So, they need a diet rich in protein such as zooplankton, mosquito larvae, bloodworms, shrimp, and raw fish pellets or fish flakes. They are also prone to overfeeding, which can lead to health issues.

The perfect tank arrangements for betta fish

Betta fish need a minimum of 5 gallons (approx. 19 L) tank for each fish. Keep in mind that the size of a tank must increase if female bettas are living in a sorority, or sharing a community tank with other species.

Betta fish love to be active. An enriched environment such as live plants, rocks, and caves will make your betta a happy fish. Avoid sharp substrate so bettas don’t hurt their fins. Do not overflow the aquarium with decorations since breathing, feeding, and breeding are activities that take place on the water surface. 

Fighting fish are used to calm waters so flow is not a must. On the other hand, a filter is necessary to keep the water clean. The minimum size tank would be 3 to 5-gallon (9 to 19 L). Fighting fish thrive in temperatures ranging from 75 to 80 F (23.8 to 26.7 °C). The ideal pH should be between 6 to 8.

Goldfish overview

Goldfish, Carassius auratus, have been selectively bred in China for over 1,000 years. They belong to the Cyprinidae family. They are native to East Asia and are closely related to carp. 

Goldfish appearance

Fancy goldfish are freshwater fish with oval-shaped bodies and double fins. Usually, they tend to stay between 1 to 2 inches (2.5 to 5.1 cm) but they tend to grow according to the environment. The longest one reached 19 inches (48 cm)! They can live up to 10 years.

Goldfish behavior

Goldfish has a calm temperament and is friendly towards other mates. They swim in the middle levels of the tank. They have a voracious appetite which can become a problem if they start competing for food. Also, they are fin-nippers. Goldfish are adaptable to the environment. This adaptability encompasses breeding, feeding, or avoiding becoming prey. 

Goldfish diet

Goldfish need a healthy diet to avoid digestive problems. Moist foods like live and frozen food such as bloodworms, daphnia, and brine shrimps are the best choices for goldfish. Because goldfish are gluttons, they also produce a great amount of waste. Always keep the tank clean.

The perfect tank arrangements for goldfish

Goldfish are cold-water fish. The water temperature should be between 60 to 75 F (15.6 to 23.9 °C), and the ideal pH is 7.4.

The swimming area should be big enough for goldfish to swim freely and decorations should neither be sharp nor block the light of the aquarium. 

A 20-gallon (76 L) tank is good for your fancy goldfish. The tank must be always cleaned and the water changed weekly, avoiding contamination. A filter is needed to maintain the quality of water.

So, can bettas and goldfish be tankmates?

When we consider a community tank, we must research to understand what are the conditions for your fish to thrive and their needs so they can live their best life.

As mentioned above, betta fish and goldfish have different needs that make sharing the same tank impractical. These differences in needs are related to:

  • Difference in temperaments;
  • Temperature;
  • Tank cleanliness and flow rate;
  • Environment;
  • pH and water hardness.

Difference in temperaments

Betta fish are territorial and aggressive fish that can live on their own and will attack at the least sign of threat. On the other hand, goldfish are amicable towards other tank mates. However, they are bigger than betta fish, have a voracious appetite, and some of them can be fin-nippers. So, maybe it is not in their best interest to keep them together.

Temperature

Betta fish prefer warmer temperatures 75 to 80 F (23.9 to 26.7 °C) while goldfish prefer colder ones 60 to 75 F (15.6 to 23.9 °C). Even if you maintain the temperature of your tank at 75 F (23.9 °C), chances are that your betta will suffer from temperature shock. This shock makes your fish lethargic and without any appetite, which can make them fall ill. Their poor circulation which is due to low metabolism can cause their fins to rot. Eventually, they will die. Goldfish also suffer from warmer temperatures. If it goes a bit over 75 F (23.9 °C), your fish’s health might be compromised.

Tank cleanliness and flow rate

Goldfish are bigger fish than bettas thus, their waste is proportional to their size. Their tank requires frequent cleaning with monitored levels of nitrite and ammonia. For that, a mature biological filter system and strong water flow are needed. Additionally, goldfish must have their tank water partially changed regularly to maintain a good quality of water. 

In its turn, betta fish are very sensitive to ammonia variation levels and can be easily poisoned by it. Contrary to goldfish requirements, betta fish prefer low current or no current at all. Additionally, bettas are easily stressed and frequent water changes can deplete their immune system making them susceptible to parasite infections and other diseases.

Environment

Given the difference in size between betta fish and goldfish, they need different size tanks. While betta fish are fine in a tank of 5 gallons (approx. 19 L) per fish, goldfish require a tank with a minimal volume of 20-gallons (76 L).

Regarding decorations, betta fish enjoy an aquarium with plenty of hiding and resting spots, as well as foliage. Goldfish, on the other hand, prefer more open space to swim, not to mention that being omnivorous they might eat or even destroy the plants. 

pH and water hardness

Fish absorb minerals through the water. Hence, they have different requirements for water hardness. Betta fish don’t need a lot of calcium if they need it at all. Goldfish need harder water than betta fish. That means that the general hardness (GH) should be between 200 and 400 ppm. But what does that mean?

It means that minerals such as calcium and magnesium can be found in the goldfish water tank. The higher concentration of these minerals means that the water is harder. If the concentration of these minerals is low, the tank water is soft. Hence, it is very important to monitor the water quality of your aquarium.

Bettas thrive at a neutral pH (7.0). Goldfish need a pH between 7.2 to 7.6 in which 7.4 is their ideal pH. The use of commercial buffers can prevent the oscillation of pH. The pH tends to increase when the water is hard and decreases in soft water, making it important to monitor the pH regularly.

Can betta fish and goldfish live temporarily together?

If there is the need to keep them together, you can keep them together for a day or two. For example, if one of your heaters broke down or you don’t have a spare tank to relocate your betta or your goldfish until you sort the issue.

However, it’s better to be safe than sorry. Always have a spare tank. It’s easier to relocate one of your fish than put your betta under unnecessary stress and in an environment that doesn’t meet their needs. 

Conclusion

Betta fish and goldfish cannot be in the same community tank.. Goldfish need colder water temperature (60-75 F)  and a bigger tank (20 gallons) than betta fish and (75-80 F and 5 gallons, respectively).

Bettas are territorial and aggressive fish while goldfish have a calm temperament. Some species of goldfish are fin nippers, which can hurt the betta known for their beautiful fins. In addition, betta fish can become underfed due to goldfish’s competitive and voracious appetite. If this situation occurs, betta will fight the goldfish back, and if the goldfish is bigger, that can lead to accidents.

Goldfish produce a lot of waste. This means that they need that the water is regularly filtered, partially changed, and high flow. Betta fish get stressed with water changes and don’t need flow in their tank.  

These fish could maybe live together on an extremely short-term basis, maybe for a day or so. But keep in mind that it can put your betta fish and goldfish at risk. 

In this post, we discussed why betta fish and goldfish cannot share the same tank and the reasons that make it impractical. If you have any comments on this topic, leave us a message below.

References

Forsatkar, Mohammad; Nematollahi, Mohammad; Bron, Culum (2016). Male Siamese Fighting Fish use gill flaring as the first display towards territorial intruders. Journal of Ethology. 35:51–59.  

Johnson, Dr. Erik L., D.V.M. and Richard E. Hess. Fancy Goldfish: A Complete Guide to Care and Collecting, Shambhala Publications, Inc., 2001 – ISBN 0-8348-0448-4

What was missing from this post which could have made it better?