Can Lionfish Change Colour? {Why Is Mine Getting Darker?}

Have you noticed your Lionfish changing colour? Are you wondering can lionfish change colour?

Is it a sign of illness, a mating signal or a mood swing? In this article, we’ll look into why your Lionfish has changed colour.

Can Lionfish Change Colour?

Yes. Lionfish can turn lighter or darker in colour for a variety of reasons. Poor water quality or other stress factors such as a cramped tank can cause colour changes. Mating, aging, defensive posturing, changes in diet and unfortunate illnesses can darken or lighten the colours of your Lionfish.

Why Is My Lionfish Turning Darker?

If you recently brought home a Lionfish that was brighter, lighter, or reddish in colour and suddenly notice that it has darkened, it’s quite common. There are several factors that could be at play. Let’s review a few of them:

  • Defense
  • Poor Water Quality
  • Changes in diet
  • Change of location
  • Ready to mate


A defensive Lionfish could change colour to a darker shade. It could be stressed, angry or simply demanding that any tankmate should take notice and leave it alone.

Stress colours that are darker may not indicate weakness or illness as much as lightening, fading or turning paler in complexion.

Poor Water Quality

This can go both ways. The colour of your Lionfish could turn lighter or darker when the water quality is messy, polluted or simply suboptimal. Do a water test and see if your ranges are somewhere near ours:

  • Water Temperature: 72-78°F
  • Salinity:1.020-1.026
  • pH: 8.1-8.4
  • Nitrates: Less than 10ppm
  • Nitrites and Ammonia: 0 ppm

Changes In Diet

A Lionfish may get trained or transitioned from eating live food to prepared meals. This process of switching from their staple diet of krill, shrimp, feeder fish to any other type of frozen, freeze dried or packaged food might cause a change in their colour. This is normal and could be restored with more variety in their diet.

Change of Location

A new environment may cause a colour change. Sometimes a Lionfish could look lighter as it swims through the middle of your tank. They may darken up when resting on a rock. Lionfish are great at blending with their surroundings in the wild on coral reefs.

Ready To Mate

Male Lionfish tend to darken up when they are ready to mate. Their bands also become harder to notice. A female Lionfish could also show slight colour changes on its mouth, belly and throat. It may look more silvery or grey at this point.

Is My Lionfish Stressed?

Try to look for these signs, symptoms and indicators of stress:

  • discoloration
  • cloudy eyes
  • spikes of ammonia, nitrites and nitrates
  • temperatures outside of ideal 72-78°F range. 
  • spots on mouth or body
  • cramped tank space
  • no hiding spaces
  • large water changes

Your Lionfish could be losing colour out of stress. After performing a water test to make sure you don’t have any spikes of ammonia, nitrites and nitrates, check the temperature to make sure it’s at or near the range of 72-78°F.

If you notice spots on its mouth or body, you may have a stressed Lionfish or one that is attracting parasites or illness. A cramped tank will also cause colour loss due to stress. Make sure you can house your Lionfish in the largest possible tank for a fully mature adult that could grow as large as 15-16 inches.

Water changes also cause stress for shorter periods of time. Try to perform smaller changes rather than one large change. 5-10% might be sufficient in a tank with only Lionfish.

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Do Bright Lights Cause Colour Changes In Lionfish?

Yes. When tank lights are on or daylight hits the tank, your Lionfish would like a shaded area to rest or hide. They tend to avoid bright lights. Caves, overhangs, rocks or planted spaces create the necessary hiding spots to give your Lionfish more comfort.

An uncomfortable Lionfish may change colour to become dull overall when the lights are too bright. Add more hiding spaces to alleviate and restore the colour loss.

Do Lionfish Change Colour When They Get Older?

A Lionfish could live around 10 years in captivity. During this time, you may notice it changing colour with age. Colour changes are also influenced by mood and diet.

A Lionfish has feelings and may show it by getting darker when they are upset or lighter when they are fearful. An older Lionfish may lighten in colour especially when there is no need to blend in with surroundings out of defense.

Why Is My Lionfish Losing Color?

If your Lionfish is losing colour over a prolonged period of time, you must consider the possibility of parasites or infection. Do you see any spots forming or cloudy eyes?

Discoloration that is short lived could be due to lighting, diet or water quality. Prolonged pale appearance could indicate parasites.

Overall, Lionfish are hardy and durable. The colour change could be more associated to water quality issues. It’s best to observe your Lionfish closer during this time to see if there are any other symptoms of illness such as refusing to eat or erratic swimming.


Different varieties of Lionfish come in multiple ranges of colours. Sometimes you will notice a colour change that is perfectly normal in a new environment or to simply blend in. Other times, there are factors ranging from water quality, aging, mating, mood shifts or oncoming illnesses.

It’s simply impossible to give you the exact reason why your Lionfish may have changed colour. The main purpose of this article today is to say that Lionfish can change colour.

We hope that these changes are not a cause for concern. Please continue to perform your best skill of observation and tank management to see if this colour change is temporary or prolonged.


Thanks for visiting for another article on Lionfish that we greatly enjoy taking care of in our aquariums. Check out more of our articles on the variety of aquatic life we research and keep. Bye for now!

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.

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