Beautiful and captivating though these two kinds of fish maybe, they should not be kept together.
There are a wide number of reasons to keep your goldfish and bettas separate and it actually has very little to do with the aggressive nature of betta fish.
The first problem you’ll encounter is that bettas are tropical fish while goldfish are not.
Bettas need their water to be between 78° and 82°F. They like to be warm and toasty because they are originally found in pools and streams in Thailand, Cambodia, Vietnam, and other southeast Asian countries.
Goldfish prefer much cooler temperatures around 74°F. They are a member of the carp family and while they originated in eastern Asia, they are now found in freshwater across much of the world.
Because of the difference in temperature preferences, you will not be able to keep both breeds happy in the same tank.
Not the most pleasant topic of conversation, but it is an important consideration.
The problem is that goldfish are not the cleanest tankmates. They produce a lot more waste than betta fish. This means that there is more ammonia in the tank when you have goldfish.
Ammonia is a colorless gas that is a byproduct of all fish waste. It is also produced when your fish process water into oxygen.
When betta fish are kept in single species tanks or on their own, the majority of the ammonia is produced by their gills. This is a fairly slow process that doesn’t tend to harm them so long as the tank is cleaned appropriately.
If you try to keep bettas with goldfish, the amount of ammonia will build up very quickly. Excessive amounts of ammonia are harmful to all fish, but bettas are particularly sensitive. If you try to keep your bettas in a tank with goldfish, you will find that they begin to suffer from ammonia poisoning.
Because you can’t see the ammonia, the first sign of trouble will be your bettas gasping for air on the surface of the water. Bettas can get oxygen from the air for short periods of time. They will come to the surface to try and escape the ammonia in the water.
You’ll also notice their gills becoming red or purple. If left untreated, the gills will start to swell and bleed. This is due to burns from the ammonia that passes through them.
As the poisoning progresses, you’ll see the effects in more of your betta’s body and behavior. The eyes will become inflamed and you may see red streaks on the fins and tails. In terms of behavioral changes, you’ll notice that your betta goes off their food and becomes lethargic.
You could try cleaning the tank more frequently to combat the extra ammonia, but even this can cause damage. Bettas are territorial fish and don’t like to be removed from their territory too often.
One of the loveliest features of betta fish is their beautiful, colorful fins. They are captivating.
You do not want anything to happen to those fins. It’s not good for the fish and it’s such a shame when you see bettas missing parts of their beautiful plumes.
Unfortunately, goldfish are fin nippers. They’re not as famously territorial as betta fish but they will nip tankmates fins when they feel encroached upon.
You shouldn’t think of bettas as poor victims, however. Betta fish are short-tempered and will not put up with fin nippers.
If you keep goldfish and bettas together, your betta will retaliate and it will likely be fatal.
Betta fish are carnivores. They can survive for a little while on plant roots but ultimately they will die without protein.
In the wild, bettas eat insect larvae and small insects. As these tend to hang out on top of the water, bettas like to feed at the surface.
Goldfish, on the other hand, are omnivores. This means they’ll eat plants and animals. In the wild, they tend to eat plants until they are fully grown when they’ll start to eat insects.
At first glance, it seems that their diet is pretty compatible. Unfortunately, this is not the case.
Some foods can be given to both breeds. Brine shrimp larvae, bloodworms, and mosquito larvae can be given to either fish.
If given live, the fish will be able to employ more natural feeding habits which is great. Although, you may find that the fish begin to compete for hunting ground and food.
You can also give these insects as frozen treats now and again for both bettas and goldfish. They’ll enjoy the snack and protein boost.
This issue comes from manufactured foods and feeding times.
Bettas prefer pellet food because it tends to be cleaner. They are fussy fish and prefer not to have sunken flakes lying around.
Goldfish are less fussy. They’ll eat mostly whatever is given to them.
The problem is that generic tropical fish food doesn’t have the right amount of protein for betta fish. They need breed-specific food to make sure they have a properly balanced diet.
Another issue is that goldfish need to be fed a few times a day. Bettas, on the other hand, generally, only need to be fed once a day.
The problem with betta fish is that they tend to overeat. Even though their stomachs are about the size of their eyes they will stuff themselves which can cause digestion issues.
If you’re using pellet food you need to be careful because the pellets can expand when wet. This can also cause problems with bettas.
There are stories out there of people who have happily kept goldfish in a tank with betta fish. I’m not suggesting that they are liars, rather that they were lucky. Lucky enough to have fish who were less fussy than your usual betta, less nippy than an average goldfish.
For the vast majority of bettas and goldfish, sharing a tank will not be a pleasant experience. Their needs are just too different to be able to keep both breeds happy.