Male Vs Female Pea Puffer- How To Tell The Difference?

Pea puffers are trendy aquarium fish. Their bright color and small size make the aquarium more beautiful. Another reason puffer fish is a favorite among aquarists is that they can be kept in small tanks. However, although maintenance is easy, a challenging issue for beginners is to identify male and female puffer fish; especially during the breeding season. Even many beginners cannot breed their fish because of this issue.

But don’t worry, if you are also facing the same problem then my today’s article is for you.  Here I will show a complete comparison of male vs female Pea puffer fish and will tell you how to identify them in the easiest way.

Quick Distinguishing Guide

Body SizeMaximum of 4 to 4.5 cm.Up to 5 cm.
ColorVivid yellow and blue stripe.Pale yellow.
BehaviorActive swimmers, and good hunters.Calm. 
Reproductive BehaviourAggressive.Rarely aggressive.
Eye WrinklesPresent.Absent.

Male VS Female Pea Puffer- 5 Main Differences

Male VS Female Pea Puffer

1. Body Size

The main way to differentiate between male and female pia puffer fish is their shape or body size. If you have multiple puffer fish together in your aquarium, you can easily identify female or male puffer fish by looking at their shape.

Male pea puffer fish are always slightly smaller in size than female fish. A male fish can be a maximum of 4 to 4.5 cm. Their body is quite slim and their shape is round. Female pea puffer fish, on the other hand, can grow to over 5 cm in size. Their body shape is thicker and less round than that of male fish.

In this case, if it is a problem to identify from the outside, you can take several fish in separate containers. Then they can identify the gender by comparing their body size and shape. But body size is not the only way to determine whether a fish is male or female.

2. Color

Since the body size of male and female fish is quite close, beginners often cannot be sure about the sex of the fish. In this case, male and female puffer fish can be identified by looking at the color of the fish.

You can recognize a male pea puffer fish by its vivid yellow color and greenish-blue body stripes. The stripes on the male are typically brighter and more solid than those on the female, And if you pay attention during the breeding season you will see the male’s color may even grow more vibrant and bright.

The female pea puffer fish, on the other hand, usually has a softer, more muted coloring, with a pale yellow or tan body and fewer pronounced stripes. You may also notice that male pea puffer fish are more territorial and aggressive than females if you watch a bunch of them.

3. Behaviour

For me, the most effective way to identify male puffer fish is by beaver. They are known to be very active swimmers. If you notice you will see them exploring and patrolling their territory. They can even become quite aggressive towards other males if they feel their territory is being threatened.

I will now tell you a secret tip to identify male fish. Release a variety of small aquatic invertebrates such as brine shrimp, mosquito larvae, or bloodworms into the aquarium. Male puffer fish are good hunters and they will come to eat them first and you can easily identify them.

Female puffer fish, on the other hand, is very calm. They rarely show aggressive behavior towards other fish.

4. Reproductive Behavior

This method is only applicable during the reproductive period. But it is quite effective. The breeding season of puffer fish usually runs from May to September. During this time your female puffers become sexually receptive and begin to exhibit several behavioral and physiological changes.

The main reproductive characteristic of female pea puffer fish is that they start moving in a specific cycle by spreading their fins. Its main aim is to present itself attractively to male fish.

Once a male fish is attracted to a receptive female, the male begins to circle the female and position himself beneath her, ready to deposit his sperm. During this process, the female usually remains still and allows the male to mate with her.

Meanwhile, you can easily identify male puffer fish by their egg-guarding characteristics.  Generally, female fish do not take care of the eggs after they are laid. So the male puffer fish takes over the responsibility of guarding the eggs. And they keep guard until they hatch.

5. Eye Wrinkles

The easiest and most effective way to identify male and female pea puffer fish is to look for eye wrinkles. This is a physical characteristic that you will only see in male puffer fish.

Take good care of the fish in your aquarium.  Fish that have a light, iridescent pattern surrounding the eye are definitely male puffer fish. Female pea puffers do not have this feature.

At What Age Can You Distinguish Pea Puffers?

Distinguishing Pea Puffers by Age

Basically, the ability to distinguish between male and female pea puffers depends more on their size and development than their age. Notice that male pea puffers are much smaller in size and have more pronounced markings, more elongated dorsal fins, and wrinkles next to the eyes than females.

Pea puffer fish reach sexual maturity after 6 months of age when they are about 2.5 cm in size. And it is only after reaching sexual maturity that fish begin to show such physical differences.

Can Pea Puffer Change Gender?

Now I will tell you the most exciting information. It can be quite shocking for you.

Pea puffers are born either male or female but can change their gender from female to male as they grow and develop. Wondering? 

This process is known as protandrous hermaphroditism, and researchers believe it is triggered by environmental factors such as population density, competition for mates, and the availability of food resources.

A pea puffer’s ovaries regress and its testicles start to develop when it switches from female to male. The process might last for a few weeks or several months, and during this time the fish may display altered behavior, including augmentation of aggression and territoriality.

However, it should also be noted that not all pea puffer fish change sex during their lifetime.  It actually depends on several environmental factors.

Why do You need To Distinguish Pea Puffer?

There are several reasons why it is important for you to identify male and female puffer fish.  First of all, if you want to breed your puffer fish you must identify the right pair. Since breeding pea puffers is a difficult task, male and female fish must be identified very carefully.

Another important factor is to prevent aggression and territorial behavior. You must have noticed the aggressive behavior of male puffer fish during the breeding season. Especially if there are multiple male puffers in the same tank, they are more likely to harm each other. Therefore, male fish should be identified and separated in advance.

It is also important to identify male and female fish to take extra care of your fish. Because if males and females are separated you will get an idea about their specific behavior. As a result, you will understand better what kind of care should be taken at certain times.


Identifying male and female puffer fish is a difficult task but very important for the proper care and breeding of the fish. If you do not identify the correct pair correctly, your fish will not be able to breed.

Sometimes even experienced aquarists cannot correctly identify male and female PEA puffer fish. But hopefully, if you follow my tips it won’t be too difficult for you to differentiate between female and male puffer fish.

I have discussed one more issue with the pea puffer. You can check this link Why Pea Puffer Puffed Up And How I Fixed It!

Howard Parker

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