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How Big do Oscar Fish Grow? And How Fast?

Oscars typically reach 10-12 inches in size and approximately 3 pounds in weight when they become adults. In rare cases, Oscars grow even bigger, reaching 18 inches in size and 3.5 pounds in weight. This depends on a lot of things, including genetics, tank conditions and diet.

When you buy an Oscar, it is certainly worth it to facilitate his growth until he becomes the large carnivore he was predisposed to be. In order to make your fish grow at a normal pace, all you need to do is to ensure ideal conditions and feed him healthy foods.

But you can go even farther than that. There are methods that can make Oscars grow even faster. If your goal is to make him grow up fast, then keep on reading. We are going to share a few highly effective methods with you that can help you with your goal.

How Fast do Oscar Fish Grow?

An Oscar fish grows 1 inch every single month. In approximately a year, it can reach its full size. Now the Oscar is one of the larger fishes you can keep at home. The average size of a full-grown adult is 12 inches. Of course, there are many varieties so some of them can be even larger, while others smaller.

No matter how big is their final size on average, you can make them even bigger. The methods we are going to share with you apply to all varieties. They even apply to most of the fish species you can keep at home.

Although every Oscar stops growing approximately at that 12-month mark, you can speed things up. If you make them grow faster during that time period, they are going to reach a larger final size at the end. Let’s see the first and simplest step that will make your Oscar grow faster.

How to Make Oscar Fish Grow Faster?

If you want your fish to grow fast, you need to buy a tank that is big enough for him to thrive. The bare minimum for an Oscar is a 55-gallon tank but buying a bigger one is even better. It is important to understand that your fish is confined in the same space every day.

He has to adjust himself to that space by not growing too much. You can also help them grow faster with a good diet. A balanced diet means that you feed your Oscar a variety of high-quality foods that provides them with all the nutrients they need.

Moreover, they can only grow in a fast pace if the water conditions are ideal and the water is clean. You need to measure those parameters every now and then and make sure everything is okay. Weekly or bi-weekly water changes are also important.

If you want your Oscar to grow really fast, then you need to keep him alone. This is the biggest and simplest trick that makes them grow fast.

When do Oscar Fish Reach Sexual Maturity?

Oscars reach sexual maturity not long after they have reached their final size. They need approximately 14 months to be ready for breeding. However, this doesn’t mean that an Oscar pair of that age is going to want to mate.

This species often refuses to indulge in breeding and rather does it at 2-3 years of age. This really depends on the individual Oscars you are keeping at home. We know approximately when they reach sexual maturity but we can’t be precise about their breeding periods.

If you are looking to breed Oscars as soon as possible, then you need to go for the more expensive option. Pet stores usually keep established pairs that are surely going to breed. Although these pairs cost more, this is your best chance to end up with plenty of little Oscars.

Do Oscar Fish Grow Faster in Warmer Water?

According to science, warm water usually speeds things up while cold water slows them down. When it comes to the Oscar fish, this is definitely true. They grow faster in warm water, but it should be only slightly warmer than the recommended.

Oscars thrive the most in 74-81 degrees Fahrenheit (23-27 Celsius). Your best shot is to keep the temperature around 75 Fahrenheit (25 Celsius). Going above the recommended temperature is risky, especially if the heater is not stable.

The water can easily become too warm for your Oscar and it will make him feel worse instead of facilitating growth.

Do Oscar Fish Grow Slower in a Small Tank?

Yes, smaller than recommended tanks make fish grow slower. This is true to any other species in general. This is why we recommend you a certain tank size and then suggest you to buy an ever bigger one.

In a small tank, your Oscar’s growth would slow down and at the end, he wouldn’t even reach his full size. The more you accelerate his growth while you can, the bigger the fish will be at the end. The tank doesn’t need to be incredibly big. It is enough to buy a tank that is slightly bigger than the recommended.

Wrapping Up

If you already know how to take good care of an Oscar fish, you can take it to the next level. You can try the abovementioned methods to make your fish grow faster and end up bigger. If you want your Oscar to be really big, you need to keep him alone in a huge tank.

You also need to set the water temperature a couple degrees higher and provide a variety of nutritious foods. The rest is really just about keeping the aquarium stress-free and the water parameters consistent. For those who want their Oscar to grow up fast in order to breed them, we have some bad news.

You can never know when exactly your Oscar fish pair is going to want to breed. The best thing you can do is to buy an established pair and you are going to have a lot of little Oscars in the long run.

avatar I’m Julia, and I used to work in a fish store for over 5 years. On this blog I help beginners care for their cichlids and share my experience and research on various fishkeeping related topics.

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