Keeping betta and goldfish together in the same aquarium is not recommended for the vast majority of fish owners.
So can Betta fish live with Goldfish?
While some people have had success keeping goldfish and betta fish together, they aren’t always the best companions. Goldfish have a tendency to want to eat anything that enters their mouths and their waste creates an environment that can be damaging to Betta fish. Similarly, Betta fish are aggressive and require different water temperatures.
With that said, it does very much depend on your individual setup. What works and what doesn’t varies from owner to owner. Some keep betta and goldfish side by side for many years without issues. Others experience difficulties almost straight away.
You must find ways to meet the needs of both in a single tank – and, as you’ll discover below – that’s hard.
Bettas Are Territorial
People who keep bettas soon discover that they are highly territorial. They value their space and they don’t like being in close proximity to other species – goldfish or otherwise. When they share a tank with other species, they are likely to get into fights that cause damage.
If you read about the history of bettas, you’ll know why this is the case. People used to call them the Japanese “fighting fish” because of their aggressive tendencies. Punters would pit them against each other to see which would win.
Thus, if you keep two or more bettas together in a small tank, it is likely that they will start fighting. Usually, the fighting doesn’t end until one of them becomes exhausted. Many bettas get agitated at the mere sight of another fish – whether a goldfish or something else – meaning that they need a large space. You should only keep bettas with other fish if you have a large tank able to accommodate them.
Experience suggests that female bettas tend to be less aggressive than their male counterparts. However, they will still display some aggression, so opting for female-only tanks does not eliminate the problem entirely.
Bettas Have Different Temperature Requirements
Bettas and goldfish come from wild fish inhabiting various ecological niches around the world. As you might expect, these niches are not the same. goldfish typically live in cooler waters ranging between 68°F and 74°F. Betta fish live in warmer waters from 76°F and 82°F. As you can see, there is no overlap that will make both species happy. The only way to achieve suitable temperatures is to zone your tank or place dividers.
If you keep goldfish in temperatures above 74°F they will eventually begin to fatigue. Likewise if you keep Betta consistently below 76°F then they will begin to behave ill. In some cases, fish will go into shock if kept outside of their preferred temperature ranges for too long. They may also die.
Bettas Cannot Live In High Ammonia Environments
There is another problem with keeping betta with goldfish: the ammonia issue.
Goldfish’s primary waste product is ammonia. They release it through their gills as they metabolize energy. When ammonia levels rise, it can harm other fish in the tank, including Betta.
So-called “ammonia spikes” occur when goldfish release a large quantity of ammonia into the surrounding water in a short space of time. These spikes are hazardous to all fish in the tank, including the goldfish who released it.
You can solve this problem by adding a filter. However, Betta fish tend to be highly sensitive to powerful filters. You may notice that they become stressed after the installation.
Added to this, goldfish tend to be messy. Their waste accumulates rapidly in the tank which, again, can harm other fish in the environment. So if you plan on keeping goldfish, you will need to change tank water regularly.
Goldfish Are Community Fish
Goldfish enjoy living in large groups with more than one mate to keep them happy and active. Without that, they may fail to thrive.
This need directly conflicts with betta’s desire to live a more solitary life. If you want goldfish to be happy, you need to keep several together in a tank. However, the more you add, the more likely it is that fights will break out with bettas.
Goldfish May Bite
Goldfish probably won’t eat bettas. Their mouths simply aren’t big enough. However, they do have a tendency to bite which means that, over time, they could damage your bettas’ fins.
Being around two and a half inches in length, bettas are usually large enough to avoid most goldfish predation. However, if you have a large goldfish, you will need to be careful. In some cases, they have been known to consume betta fish.
In summary, keeping goldfish and betta fish together is not a good idea. While some owners find strategies that work for them, it is technically challenging and probably not worth the effort.
For example, if you want to keep goldfish and Betta in the same water, you will need a 30-gallon tank or more. You will also need to provide plenty of shelter, such as rocks, ornaments and plants, so that fish can get away from each other. To deal with the ammonia problem, you will need to choose a moderately powerful filter – but it can’t be so strong that it disturbs the Betta fish. You may also want to use a tank divider so that you can separately regulate temperature and prevent biting.
A better approach might be to simply use two tanks. This way, you can avoid biting problems, and create conditions that will allow each species to thrive.