Oscar fish are predatory fish, and they like to eat live foods including different insects, small fish, various worms, etc. But can oscar fish eat goldfish?
Oscar fish eat goldfish, and the use of feeder goldfish is very common as oscar fish food. They can live together only if the goldfish size is large enough that doesn’t fit oscar’s mouth. However, still goldfish may be subject to immense stress because of the fin-nipping tendency of oscar fish.
Here I’ll discuss what should be wise, whether keeping oscar and goldfish together in the tank or using goldfish as the food for oscar fish.
Care Requirements About Oscar Fish & Goldfish
|Basic Info & care requirements||Oscar Fish||Goldfish|
|Maximum Size||20 inches||8-12 inches|
|Expected Lifespan||20 years||10-15 years|
|Ideal Tank Size (Minimum)||55-gallon||20-gallon|
|Compatibility||Large passive fish||Peaceful fish & not fin nippers|
|Water Temperature||77-82 °F||61-77 °F|
|Carbonate Hardness||90-180 ppm||70-140 ppm|
|General Hardness||100-200 ppm||90-340ppm|
|Ammonia||0 ppm||0 ppm|
|Nitrite||0 ppm||0 ppm|
|Nitrate||<50 ppm||<50 ppm|
Challenges of keeping oscar and goldfish together
You can see from the above two tables that the tank requirements differ significantly for oscar and goldfish.
Oscar fish are of tropical origin and they prefer warmer water. However, goldfish are cold-water fish and require a lower temperature range than oscar.
So, keeping them together is challenging. Maintaining the tank temperature at the recommended range for oscar will make goldfish hyperactive, and their lifespan will reduce.
On the contrary, setting the tank temperature near the goldfish tank’s ideal range will create difficulties for oscar fish.
Oscar can’t live in cold water and they become vulnerable to diseases if they are exposed to cold water for a prolonged period.
The common value for the temperature for both the fish is 77 degrees Fahrenheit. However, it is extreme for both the fish. So, it’s not wise to do that.
Also, oscar will eat goldfish. They’ll think goldfish is nothing but food. Unless the goldfish is big enough than oscar, it won’t survive.
If the goldfish is not eaten by oscar, it will be under constant stress because of bullying and chasing by oscar.
In addition, goldfish are extremely messy. In conjunction, oscar fish and goldfish will produce tons of waste that will be difficult to manage. You’ll need an extra powerful filter to manage that.
Still, How Can You Keep Goldfish & Together?
Still, if you are interested to keep goldfish and oscar together follow the guidelines below.
- Make a big tank so that they can have ample space, and balance the temperature.
- Provide plenty of hiding places in the tank. Add decors, caves, driftwoods, etc.
- Use a tank divider to keep them separated but in the same tank.
- Feed your oscar fish well. When they are well fed they will be less likely to chase other tankmates.
Using Goldfish As Feeder Fish
Oscar fish love lives food. Chasing and eating the live food by the oscar fish is a treat to watch.
Goldfish are nutritional for oscar, they are a source of marine protein for oscar. You can see the below video of how people are feeding goldfish to oscar.
Feeding goldfish is a good idea as it is cheap and oscar’s loved diet. Breeding goldfish in bulk is pretty common only to feed to predatory fish like oscar.
However, one thing you need to keep in mind is that live food including goldfish can carry disease. If you feed sick fish your oscar fish can also be affected by the disease.
It is best if you can breed goldfish at home by yourself. Otherwise, ensuring that all the goldfish are healthy to eat is challenging.
If you don’t have a breeding facility, I suggest you set up a quarantine tank. The purpose is to quarantine goldfish that you’ll buy from the pet store before feeding to oscar.
That will ensure there are no diseases brought by the goldfish. As an occasional treat or even as a regular diet you can provide goldfish.
Another concern is the higher fat content in goldfish. Also, goldfish contain higher thiaminase that destroys vitamin B1.
So, the predatory fish eating a lot of goldfish will consume a large amount of thiaminase which can lead to vitamin B1 deficiency. illness and death. 
What Other kinds of fish can Oscar eat?
Oscar fish eat virtually everything. They can eat any fish that is smaller than them.
Therefore, you need to be careful while choosing tankmates for oscar fish. Bottom feeder fish are a good choice as their tank mater because they occupy a different layer of water than the oscar.
They also eat invertebrates like shrimps and crayfish. Although invertebrates usually live near the bottom surface still oscar eat them. Below is the video of eating a crayfish by oscar fish.
Besides any other fish, oscar fish can eat various human food including salmon, tuna, prawns, shrimp, chicken, etc.
That should not be the regular diet. But as an occasional treat and to bring some varieties you can add those in their diet.
Can A Smaller Oscar Fish live With Bigger Goldfish?
So, if the goldfish is bigger than the oscar fish, can they live together then? They can live together, but oscar fish having fin nipping tendency can stress goldfish.
A fish under stress is susceptible to disease, and its lifespan will be reduced significantly. So, even if the oscar fish is smaller than the goldfish, it is not a good idea to keep them together.
Another thing is, oscar grows very fast rate. One inch per month, meaning they can grow almost 10-12 inches in a single year.
So, the small oscar will outgrow the goldfish at one point and may eventually eat the goldfish.
Also, they will fight over the food provided and they can fight each other. Often goldfish relinquish the battle and hide behind decor or other stuff in the tank.
Once I had a goldfish tank where there were some Platy fish. At that time I didn’t know that platies are fin nippers . They used to chase the goldfish, and eventually, I saw that goldfish have no respite.
After a few days of exposure to constant stress the goldfish died. The platy was much smaller than the goldfish.
The same will happen with Goldfish and Oscar. Even if the oscar is smaller it can force the goldfish to death.
What Goldfish Food Can Oscar Fish Eat?
Feeding Oscar goldfish food is not a good idea. Oscar fish need more protein-rich food, while goldfish don’t need much.
The food prepared for goldfish is not high in protein. On the other hand, ideal food for Oscar fish are carnivore pellets, live insects, and other meat-based food.
So, Oscar may live on goldfish food but it’s not perfect for them. You should find the recommended diet for Oscar fish to keep them happy and healthy.
Oscar will eat goldfish if it’s a perfect size for them to eat. You can also provide feeder goldfish to your Oscar. However, high consumption of goldfish is harmful to Oscar fish.
Therefore, you should be careful enough about feeding goldfish to the Oscar fish. If you do, try to breed by yourself, or quarantine first if you brought them from a pet store. In addition, try to feed in moderation.
Keeping Oscar and goldfish is not ideal, and is not recommended by experts. It requires a lot of hardship for the owner to maintain the tank’s condition. As well as goldfish won’t find it easy to live with Oscar even if it is bigger than Oscar fish.