Can a Shark Outgrow Its Tank?

If you read a lot of motivational quotes, you have probably read this quote more than once “A shark in a fish tank will grow 8 inches, but in the Ocean, it will grow to 8 feet or more. The shark would never outgrow its environment, and the same is true about you.” This particular quote has led to many misconceptions. However, let’s see if it’s really true.

So, can a shark outgrow its tank?

The correct answer is yes, a shark will outgrow its tank if it isn’t the right tank size for it. It’s a common myth that a shark would never outgrow its tank, but in reality, it will. The size of the shark and the tank you keep it in matters.

Before you decide to keep a shark in a tank, you need to adequately research the shark and how big they presumably grow. Keeping a shark in a wrong size tank can either lead to stunted growth or death of the shark.

What Do I Need to Know before Keeping a Shark as a Pet?

When hobbyists visit pets stores to purchase a shark as a pet, most sharks often sold to them are catfish. Pet stores sell these as freshwater sharks or one of the carp species.

However, keeping real sharks as a pet is now starting to become a thing, especially for people that can afford to take care of them. But, before you keep a real shark, you need to research if it is legal to keep it as a pet. And of course, how well it can survive in captivity.

Without that, you are posing a massive risk to the shark or could even get arrested for it.

What are the Factors that Affect Sharks’ Growth?

There are a lot of things that can affect sharks’ growth, though, biological waste products are one of the many reasons for stunted growth in sharks

Water quality


Allowing the build-up of nitrates in your tank will not only stunt the growth of your shark but might also result in death. Keeping your nitrates below 25 mg is very important.

Suppose nitrates is already too much in your tank, you can remove it by changing the water. The presence of too many nitrates in your tank would not only lead to stunted growth in your shark but also lead to algae growth that is difficult to get rid of.


Hormones fish are essential but rarely put in consideration when looking at the causes of stunted fish growth in aquariums. The reality of it is, pheromones play a vital role in sharks’ development. In their natural habitat, the largest sexually matured fish gets to mate first and lead the school as well.

However, all of these are hardly possible to achieve in a tank. So, lack of all these essential things can affect your shark’s growth or even lead to the cause of death.

This is why it’s essential to change the tank water as frequently as possible to try at least to replicate their natural habitat.


Sharks excrete ammonia through their gills as waste. If you do not get rid of ammonia is in your shark’s tank and it stays longer than required, it can cause damage to their gills and membranes.

A shark that suffers from ammonia burn would have black patches all over its gills. A damaged gill would result in the shark not being able to breathe properly.

All these can contribute to its stunted growth if the shark cannot get enough oxygen.


Another factor that can affect fish growth is diet. When in the wild, sharks have access to choose their prey, graze throughout the day if they want to. But when in a tank, they only get to f what the hobbyist can feed them.

Most foods sold to hobbyists are food full of fillers than no fish would eat if they were in their natural environment.

Quality of Water

Now you know, nitrates and pheromones can cause stunted growth in fish. As a result, you need to know when to change the tank water.

The amount of water that you must change and time to change this water needs to be put into consideration also. Try to ask your local store to get accurate information.

The suggestion of changing about 25% of water monthly is sometimes not ideal.

Water Chemistry

Replicating the natural fish environment is also critical in fish growth. This will not only reduce the stress level of the shark but also gives it room to grow.

Fish kept in the wrong kind of environment suffered a high increase in stress levels.

For example, Cichlids from Africa need to grow in an environment with a high level of pH and hardness of water, whereas dwarf cichlids require a very high acidic water.


Just like it happens in humans, sharks of the same species would not grow at the same rate.

The research found that fish kept and bred in aquariums with the same male and females for generations would most times end up producing pups relatively smaller than in their natural environment.

Experts also suggested there might be a connection between the environment and the growth rate of some shark species.

All this implies that if you would like to see your pet shark grow to its maximum, you need to provide more than enough space for it to grow.

Now that we already established that large sharks would not remain small because of the size of the tank it is in. You may need to sleep over getting a shark known to get bigger as a pet if you can’t afford to replicate its natural environment.

How Does a Shark Grow?

Before we can consider how a shark grows, we need to understand the definition of growth. Growth is the increase and development of an organism’s size throughout its life history.
So now, let’s look at how sharks grow. Sharks grow just the way other animals grow. They get their first nutrient from the egg sacks then proceed to feed on small fish.

As they grow older, they feed on bigger fish. The nutrients they get from feeding on these prey increases their growth.

What is the Right Size for Any Given Shark Species?

There is a lot of information online where you can do the research for the right size of your given species. You can also check through our website to get the information you need on any shark species.

How Big Do Sharks Grow?

How big a shark would grow solely depends on the species. Some sharks don’t grow as much while others grow very big. For example, male great white sharks grow as much as 9.8 to 13.1 feet (3 to 4 meters), while the females grow to about 13.1 to 16.4 feet (4 to 5 meters).

Do Great White Sharks Outgrow Their Aquarium?

The great white shark is one of the most feared predators in the sea. Its iconic title earned it many roles in movies and books, which leads to the question of why they are not found in any aquarium.

Is it because they would outgrow their aquarium?

Many believe that with this shark’s Iconic title, it should be a source of attraction in many aquariums.

Aquariums can be home to many shark species, but not to the great white shark because the same tank walls that serve to captivate this fish and save them has been the source of their problem.

Great white sharks naturally evolved to travel at an incredible speed in the open Ocean. However, when kept in a tank, they tend to run into tank walls causing many injuries to their body.

This may lead to the sharks not wanting to swim any longer. And, for a shark that continuously needs to pump water over its gills to breathe, this might result in death.

Research also found that being surrounded by the glass also confuses their electroreception system. They use this to give electric signals when they are in the open Ocean.

These are the reasons why you wouldn’t find a great white shark inside an aquarium. The few great white sharks that were tried in the past struggled with all of these issues.

While their size also matters, them outgrowing their tanks isn’t the real reason aquariums don’t keep the great white shark.

So, Will a Shark Outgrow its Tank?

It’s important to know how big your shark is going to get before purchasing it.

If a shark would outgrow or not outgrow a tank majorly depends on its species and the size of the tank we are talking about.

If it isn’t the best tank size for it, best believe your shark would outgrow it or, in many cases, experience stunted growth as a result of being kept in the wrong tank.


By now, we believe you have gotten the answers to your questions about sharks and if they can outgrow your tank.

For emphasis, a Shark would certainly outgrow your tank if it isn’t the right size for it. Or, sometimes not even reach its normal size because of tank size.