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can guppy fish change colour

Can Guppy Fish Change Colours?

If you are a guppy fish parent then you might have noticed that guppies can and do change colour. But is this normal or is it something to worry about?

Guppies change colour due to age, breeding status, and stresses caused by their environment such as temperature, diet, water quality, over-crowding, bullying, and diseases.

In this article, I’m going to share with you the possible reasons why guppies change colours, when they first get their colour,and how you can help to make your guppies more colourful.

So without further ado let’s dive in!

red blonde guppy
A Red Blonde Guppy

Here are some possible reasons why your guppy is changing colour:


When you look at the fish in the pet shop or online, you might have noticed that some of them are very brightly coloured.

But when you bring them home and add them in the tank then most often you might notice that the guppy fish change their colour. They can become noticeably paler.

So why does it happen? Yes, you guessed it right! It is due to their sudden change in environment.

Colour changes, discolouration or spots on your fish are some of the signs that indicate they could be suffering from stress.

Now, this stress could be due to many reasons. So let’s also discuss them one by one.

1. Sudden Change In Environment.

A sudden change in environment can cause the fish to feel stressed or frightened, as they are unsure of their new surroundings. You will notice that any new guppies added to your tank will look pale in colour. As they get used to their new home you will see their colouring gradually getting brighter.

I have 2 male guppies in my tank-one orange and one yellow. It took a few weeks for them to get their lovely, bright colours. This was when I knew that were fully settled in their new home.

yellow guppy
My handsome yellow guppy fish.

2. Over Crowded Tank.

Whenever you put too many fish in the same tank then the chances of stress between the fish increases dramatically.

Guppies have beautiful fins and if you overcrowd or keep them in a community tank with lots of other fish then you have to be careful.

Some fish might bully or nip the fins of your guppy and ultimately stress it. Which will as a result, make your guppy look pale.

So, either choose a much bigger tank where everyone has lots of space, have a guppy only tank, or be very careful to not overcrowd your tank.

3. Incorrect Temperature.

Guppies require between 72-82 °F (22-28 °C) water temperature.

Keeping guppies in too hot or too cold water can cause them to feel stressed which will ultimately affect their colouration. It is also bad for their health.

4. Aggressive Tank Mates.

If you have aggressive tank mates that always keep on chasing your guppy or nipping at their fins, then it is going to start to feel stressed.

You should have some ornaments as hiding places in your tank. as well as some plants. This will reduce the chance of the fish coming too close to each other and trouble brewing.

Also, tankmates should be chosen wisely so that they don’t stress your guppy. Don’t add any fish in that are renowned for nipping fins.

5. Poor Water Quality.

Not having good water quality in the tank will not only impact the guppy’s colour but also it will cause it to get stressed. Make sure you test your water regularly, and carry out partial water changes when required.

guppy fish

What is Stress in an Animal?

Stress is whenever an animal is not able to maintain its normal physiological state because of various factors that is affecting its well being.

Stress is caused in a fish whenever it gets in a situation which is outside its level tolerance. Some fish species have a higher level of tolerance than others.

It is your responsibility, as a fishy parent, to make sure that your fish don’t get stressed and thus remain healthy, active and retain its bright colours.

Now let’s discuss the other reasons for the colour change in guppies.


Yes, getting older can be a factor leading to a colour change in your guppy. And this is not just with fish. In any living body, as it starts aging, the body’s systems and functions start to deteriorate slowly.

With ageing, cellular growth is reduced. So if your fish is getting on a bit, you may start to notice a change in their colour.

One side note: If your guppy fish is lying on the bottom of the tank and has been for some time, and is looking very pale (almost translucent), unfortunately it is very probable they have passed away. Hopefully, you will have noticed a change in their colour well before this, and have taken steps to rectify any problem.

Change In Water Parameters

The water parameters also impact the change in the colour of the guppy fish. If you haven’t maintained your tank for sometime, then surely the level of toxins might have increased.

According to, differences in the mineral content of the water where a fish was born and where it is living now can also cause the change in the colour of a fish.

So bad water conditions, or a big difference in pH levels can be a few of the reasons why your guppy has changed colour.


You might be noticing colour change in your guppy fish because of infection or disease.

For example, if your guppy is suffering from Ick, then you would notice small white spots on their skin and fin.

Improper Diet.

Although not directly, food plays a vital role in the colour of your guppy.

The quality of diet you give to your guppy and also the amount will decide whether they will show bright colours or dull colours.

If you give good quality food to your guppy they will become healthier – thus guppy will show brighter colours.

If you give bad quality food that lacks nutrients – guppy will become ill and weak- thus it will start showing dull colours.

As a general rule, you shouldn’t overfeed or underfeed your guppy. And regarding the quality of the food, the more nutrients you give to your guppy, the better it is for them.

When Do Guppies Get Their Colours?

brightly coloured guppy

Before knowing how to make guppies colourful, it is important to understand when they start gaining colours.

At first, the guppy fry may not look colourful or vibrant. But when guppies are between 1 to 6 weeks, they start to gain some colour.

Genetics, diet and metabolism are some of the factors that contribute to when a guppy will get its colour.

Male guppies are a lot more colourful than females simply because during mating bright and vibrant colours help them to attract the mates. They need to stand out from the crowd!

So this was about when a guppy gains colour.

Now, the chance are you have come across this article because you are worried about your Guppy losing their colour? (If it’s gaining colour then congrats. It’s really great to see colourful guppies moving in the tank, isn’t it?)

How Can I Make My Guppies More Colourful?

Here are some tips to make your guppies more colourful:

  1. Make sure all your guppies are fed adequately. Getting the proper amount of food is crucial for growth and colouration.
  2. Always try to give quality food to your guppies which is full of nutrients. This will help ensure better growth and colouration.
  3. Make sure to keep your guppies with peaceful tank mates that don’t harass or bully them.
  4. Have your guppies in an adequately sized tank, and also avoid overcrowding.
  5. Maintain proper and required water temperature and water quality for your guppies. This will allow them to remain active, healthy and show bright colours.
  6. Make sure you have the correct male to female guppy ratio. Ideally, it should be 1 male to 3 females.
  7. Have enough hiding places, use proper lighting and create such an environment to keep your guppies stress free.

You can also watch this video about enhancing the fish colour of guppies:

Why Has My Guppy Turned Black?

Generally, a guppy turns black to show aggression. However, they can also turn black due to some infection, stress or due to ammonia positioning.

Some guppies turn their eyes black to warn the other fish whenever they feel aggressive. So if you see black eyes then probably your guppy wants to attack the other fish.

But if you are noticing the tail of your guppy turning black, then sadly it can be because of some infection.

Also high ammonia concentration is not good for fish. Your guppy’s tissues can get damaged and even cause change in coloration, black patches.

Why is my Guppy’s Head Turning Red?

Generally, due to ammonia poisoning, red spots can appear on your guppy fish. Ammonia poisoning occurs when the fish tank’s pH level gets elevated.

If there is a problem with your ammonia levels, you may notice your guppy fish gasping at the surface for air. You may also see that the gills of your guppy become a reddish colour.

Make sure you carry out a full water test.

Ammonia poisoning is more likely to occur because you have either added fish to a tank that hasn’t fully cycled yet, or you have added too many fish to the tank too quickly, which has caused the ammonia to spike.

If you add any fish to a new tank then the ammonia level may rise quickly simply because of the lack of the beneficial bacteria which can transform these into nitrates.

Ammonia, even in small amounts can be quite harmful for your fish. And it is always better to avoid ammonia poisoning rather than having to treat your fish for it.

guppy fish


So, do guppies change colours? Yes, guppies change colours mainly because of stress or some change in their environment. But there could also be reasons like aging, poor water quality, insufficient diet, and infection that causes the change in colour of the guppies.

Generally, if they go brighter, it is a good sign. However, if they go paler, or change colour in places, then there is something wrong.

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