Guppy Behavior Myths and Realities

Michael Langerman
9 min readJun 13, 2020


Colorful guppies are one of the most popular aquarium fish in the world.
They are so popular that some aspects of guppy behavior are proverbial even among those who have never kept them as pets, how about that!
The existing stereotypes are often misleading and cause confusion and mistakes when it come to taking care of guppies.
You know if your dog or cat is happy or wants to play or whatever else due to the way they behave.
Animals express their feelings through their body language.
And so do fish.
Observation is the key to understanding them.

Let’s observe guppies’ behavior together.
Behavior patterns are affected by age, gender, environment, and personality.
Newborn guppies of both genders look and behave alike.
They stay together as schooling fish do.
And they all behave like kids do.

The largest and the most active prevail.
The largest female in the school starts establishing her dominance at a very young age.

Here you can see four month old guppies of the same parents in two aquariums.
One male with a couple females in each nursery.
Male guppies become distinguishable from females at the age of a couple months or so by the shape of their fins, rainbow of colors, body shape, and…behavior!

This young male is full of energy and curious about everything that moves.
He is hot fire :)
Well natured male.
Females are much more discreet.
Female guppies mature later and grow bigger than males do.

Here is another male sibling.
This one is keeping to himself.
He guards his territory and food.
He chases away females!
He is acting kind of…mean, don’t you think so?
So, here we observed two male guppies with opposing personalities.

In this period of life guppies behave as teenagers.
Inexperienced teenagers could be rough to each other or carefree and happy, on the other extreme.
The golden middle comes with time :)
The larger female here is chasing away the smaller female.
She is not bigger than males yet and…she still has to figure out males.
At this age of development, the young male is still figuring out females too.

Now look at this young male… the one that has been “angry”.
Apparent changes in his behavior puzzles all three females!
They literally stare at the male.
Apparently he has grown up enough to realize something very important…important about females and the purpose of life.

From now on it is a female guppy, the queen, who is in charge here.
And she leads on her whim!

Male guppies are persistent in the “catch me if you can” game.
Most common orange-reddish colors among male guppies serve one purpose — to attract everyone’s attention.
All predators hiding around and certainly guppy females are attracted by hot fire moving guppy tails.
Guppy males are naturally skillful bullfighters!
In the wild, the bright colors of guppy males lure predators away from guppy females.
It helps females with babies survive.
For that sake, male guppies are disposable.
Here you can see the queen charge the male while he follows another female.
And the queen charges the female too!
The queen reserves all rights on everything in her domain and certainly on the only male.
But the male has to prove himself worthy…any time and every time.
This time the female managed to nibble at his fin.

It does not stop the male from playing the game.
Guppy males are cheerfully persistent.

Older males often sport torn tail fins as a result of mistakes they made.
The older guppy females are larger, stronger, and faster than males.
Playing around with an irritated big guppy mama is a dangerous adventure.
Guppy females usually stop chasing the male if he moves quickly enough to keep a safe distance.

Otherwise…the damage could be very severe.

The male with a severely damaged tail fin cannot swim and will die.
Guppies are toothless fish, and yet…

I have never seen a female guppy get hurt this way.
Only males get hurt like this and it happens on very rare occasions.
The game is over for this male.
Males are disposable in guppy society.

Guppy males work very hard all day long to tire a female for her short submission.
Every guppy male is a little tireless bullfighter in this respect.
Males are smaller, but more energetic.
Eventually the female yields.
Male guppies are very persistent in courting females.

Here is an aquarium with 2 males and 1 female.
I just moved the fish into this aquarium.
Both males are of the same age, size, and color.
How does she choose which male to mate with?
She does it in the stress free old fashioned way by letting the boys figure it out first between themselves.
The males compete against each other until one yields.
She just has to watch and wait.

And then she will charge the winner.
Yeah boys, go wave your tails.
And that is what guppy males do.
They dance around each other until one gives up.
It is a fascinating dance to watch.
The entire aquarium is a dance floor for them.

Did you see how they touch each other with tail fins :)

Eventually one male yields.

The other male stays closer to the female — the queen.

He better watch his tail now!

The queen can charge him at her whim.

And the other male is watching him too from a distance, for now.

Here are 3 young male siblings.
I did not put a female in this aquarium yet.
Nevertheless, the males compete against each other, whether a female is present or not.
The smaller male tirelessly challenges the larger male.
This is a never ending game for younger, but fast growing guppy males.

Here is an aquarium with males of different ages and sizes.
Fish grow all life long.
So the older fish are usually larger.

The young, energetic male challenges and eventually wins over the older, larger male.
Now the young male can stay close to the queen.

Guppies eat newborn babies.
And it’s actually the mother or other females who would do it.

Male guppies are less likely to attack babies.

Here you can see a mother guppy in a nursery with newborn fry.

She scares babies away, but does not go all the way after babies, the way she would charge a male.
She wants babies to swim away.

Females would eat only weak or sick babies that cannot swim away fast enough to hide from potential predators.
Eating a sick baby would save the rest of the school.
Getting more live plants in the aquarium helps save more babies.

Guppies breed frequently throughout their fertile age that goes up to 2 years or so.
However, they breed only under appropriate breeding conditions.
Those conditions include all parameters!
Food, water quality, temperature, dimensions of the aquarium, and much more.
All parameters need to be adjusted to meet needs of your fish as necessary.

In this example, the breeding guppies stopped moving in the aquarium where they have been growing and already had babies.
They do not move.
Forget about making babies.
What is going on here?!

Remember that fish grow all their lives…but aquariums don’t.
The narrowest size of any aquarium should be 3 times or more the size of the fish.
From that, we can estimate the minimum amount of water per fish and how many fish could be in this aquarium.
This particular aquarium is fit for a dozen or so newborn guppies.
It is fit for a young breeding family of 3 guppies.
But they grow and the aquarium gets too crowded for them.
Only the size of the fish has changed.
One and any unfit parameter prevents guppies from breeding.
And it’s true for all living things.

I move one female out of this tank.
And the remaining two guppies start swimming around.
They will have babies here again.

Guppies are cheerful schooling fish.
Keeping a single guppy secluded, even temporarily, is very harmful to the fish.
Guppies have feelings and can express their emotions through their body language.
Here you can see a young, lonely male in a separate nursery next to the aquarium with other guppies.

He would not swim away from this wall for hours, watching other fish and showing all signs of depression.

Prolonged seclusion has deep negative effects on guppies and they can die from it.

Learning and recognizing behavior patterns of your fish and other pets helps understand their needs.
It takes time…probably more than one guppy’s lifetime to fully understand all the complexity involved in their behavior.

Give it time to observe and understanding will come.

Have fun and happy guppies :)