Why Do Angelfish Hide? (And Sometimes Prefer The Bottom)

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For years I’ve been asking myself why angelfish hide. I have noticed that phenomenon so many times over the years. In some cases, they have stayed behind plants, while in others, they just haven’t left the bottom of my tank. To solve this problem, I began to research and test different techniques myself.

Angelfish hide because of adverse water conditions: wrong temperature and pH levels, high nitrate concentrations, and hard water. Hiding could also be a result of stressful aquarium conditions, overcrowded tanks, aggressive companions, and the fear of predators.

Sometimes it is merely the natural angelfish behavior. However, if it is one of the reasons above, you should do something about it. Otherwise, your fish’s health might be compromised, and its lifespan may be shortened.

Also Read: Stress In Angelfish

Reasons Why Your Angelfish Frequently Hide

Since it might indicate an underlying issue, allow me to present you with a few reasons for the phenomenon. Hopefully, you’ll be able to figure out what the case is in your aquarium.

1. The Water in Your Aquarium is Too Hard

Does your aquarium consist of hard water? If you are not familiar with the term, it merely means your tank might feature high levels of calcium, magnesium, carbonates, and sulfates.[1]

Angelfish, like many other fish, prefer soft water. However, if you’ve used tap water for your tank, there is a good chance it is not entirely suitable. For that reason, if you have recently changed the water of your aquarium, angelfish might be hiding due to the hardness of the water. 

Testing The Water Hardness

If you suspect this might be the case, you must check how hard the water in your tank actually is.[2] First, buy a hardness test kit; it can either be the strip test or the reagent test.

The strip test involves collecting water in a small bowl from your aquarium and dipping the strip into the water. Then, the color will change depending on the hardness of the water. Then, go through the instructions manual to figure out if the water is hard or not.

The reagent test involves collecting the aquarium water in a test tube. After that, you have to add a few drops of the chemical which comes along with the test kit.

The watercolor will change depending on how hard the water is. You should use the color chart, which comes along with the package to determine the reading.

In both cases, if the water is too hard, you should not put it back into the aquarium. Instead, make sure you throw it away and replace it from another water source.

How to Turn Hard Water Into Soft Water

Now that you know to measure the hardness of water, the next question which you might have is how to soften your aquarium water. Fortunately, there are ways to do so.

Reverse Osmosis

Reverse Osmosis is known as RO in short. The RO filter can remove up to 99% of the minerals, chemicals, and other particles from water. That is why introducing this filter in the aquarium can help you reduce the hardness and convert the water into soft water.

Water Softening Pillows

Water softening pillows use a chemical filtration system. The aim is to reduce magnesium and calcium levels in the water. You can add them to your current water filter to make it more effective.

However, instead of adding them, it is better to go with the RO filter, as mentioned above. That is because water softening pillows increase the sodium levels (while decreasing the calcium and magnesium levels).

Use Peat Moss

Peat moss[3] consists of various mosses species. You can add to peat moss to the aquarium filter or add it to a pillowcase. Another option which you have is to fill a bucket full of aquarium ready water and keep peat moss in it for a week.

After that, you can remove the peat moss and strain the water into the aquarium. As you can see, using it is quite easy. What it does is binding the calcium and magnesium ions and therefore reducing the hardness of the water.

Once you convert hard water into soft water, you may find your angelfish once again roaming around the aquarium freely rather than sticking to their hiding spots. Nevertheless, if they don’t, you may try the other solutions below.

Also Read: Angelfish’s Mouth Stuck Open

2. Stressful Aquarium Conditions

Stress can be one of the prime reasons why your angelfish might continuously be hiding. One of the reasons for stress is the change in habitat. 

To find the cause of this stress, you have to ask yourself questions like:

  • Have you changed the aquarium interior or decor recently?
  • Have you changed the aquarium itself?
  • Have you placed the aquarium differently in recent days?
  • Are there are no hiding places inside the aquarium?

Many of you might be puzzled by the 4th question on this list. The truth is that angelfish are native to the Amazon basin. The amazon and rivers in Southern America are rich in flora and fauna. 

That is why in their native habitat, angelfish get a lot of plants as well as other obstacles behind which they can hide. In the absence of these features, they might feel stressful. It is one of the reasons why finding the answer to the fourth question is essential, as well.

Depending on the answers to these questions, you can make modifications to your aquarium to ensure that everything resembles their natural habitat, or that you give them at least a few hiding places.

3. The Temperature And pH Might be Wrong

Angelfish prefer temperature around 78F to 80F. Similarly, the pH levels should be between 6 and 8. If the water temperature or the pH levels are not right, angelfish might go into hiding and prefer to stay there for an extended period.

In case the water conditions are not correct, angelfish might not come out even when you try to feed them. It can be a big problem. That is why you have to use a pH testing kit and a thermometer to test the water conditions and modify them accordingly.

You can use a heater to increase the water temperature or add some cold water to reduce it. Similarly, the pH levels can also increase by adding crushed coral or baking soda to the aquarium. Also, to decrease the pH level, you can add peat moss or use an RO filter.[4]

The aim is to get the temperature and pH level in the desired range so that the angelfish get comfortable in it.

4. Your Tank is Overcrowded

Angelfish are pretty gentle and sensitive. Therefore, if you have an overcrowded aquarium, rather than competing with other fish, they will probably start hiding.

This could also increase their stress levels and take a toll on their health. While most aquarium owners know that it is sometimes difficult to decipher whether or not the tank is overcrowded.

Some of the consequences of an aquarium being overcrowded are:[5]

  • High nitrate levels
  • Aggression among fishes
  • Angelfish being attacked
  • Low oxygen levels
  • Fish growth reduction

If you notice these symptoms, then most likely, the angelfish are hiding due to overpopulation in your aquarium. The solution is to either give some fishes away or buy a second tank. The last will allow you to shift gentle species along with the angelfish and might solve the hiding issue.

5. The Angelfish Share Aggressive Companions

Have you introduced any new fish in your aquarium? If yes, this might be the reason why your angelfish has gone into hiding. 

There are certain species of fish which do not go well with angelfish. These include:[6]

  • Tiger barbs
  • Betta
  • Peacock bass
  • Green terrors
  • Jack Dempseys
  • Silver Arowanas

All the species of fish are pretty aggressive and would probably bully around the angelfish. Generally speaking, you should avoid adding aggressive fish to your aquarium when you have angelfish. In case you have already introduced any of these species, it comes as no surprise that your angelfish has gone into hiding. 

6. High Nitrate Levels

If the nitrate levels in your tank are relatively high, angelfish are likely to go into hiding. 

The causes of high nitrate can be plenty, like:

  • Fish waste
  • Leftover food
  • Decomposing plants

To find out if this is the cause, you have to measure the nitrate levels in the aquarium. You can buy nitrate testing kits online are from the aquarium stores. It will help you know the level of nitrates right away.

The nitrate levels should be between 5 ppm to 10 ppm. If the levels are above 20 ppm, it is very high. In this case, you should act to reduce it.

The steps which you can take include:

  • Change the water regularly to lower the nitrate levels. If it is about 20 PPM, it is better to replace 75% of the water of your aquarium within the first week.[7]
  • Add living plants to your aquarium so that the nitrate levels go down.
  • Use an RO filter to reduce the nitrate levels.

These are probably the most apparent measures when it comes to reducing nitrate levels in aquariums. Once their environment is well balanced, follow your angelfish and see if they had left their hiding spot.

7. The Fear of Predators

Many times, angelfish might go into hiding due to a predator being introduced in the tank: 

“However, when something scary, such as a diver, approaches an angelfish, it often darts among coral branches, Marshall notes.”[8]

Therefore, if you have introduced a predator in that fish tank, the angelfish are likely to stay hidden. It is a natural response which you cannot modify. The only thing which you can do in such a case is to isolate the natural predator so that the angelfish do not feel threatened inside the aquarium.

Also Read: Angelfish Sitting At The Bottom

When Does Hiding of Angelfish Indicate a Problem?

Going into hiding for a relatively short duration is normal for angelfish due to their natural habitat. Still, if they are continuously in hiding, it may raise a concern. With my guide above, you can determine the cause and act accordingly. 

Some of the symptoms which indicate that hiding of the angelfish is a problem include:

  • Angelfish are hiding throughout the day or for days together.
  • Angelfish do not come out even during feed times.
  • The Angelfish seem lethargic.
  • There are wounds or injuries on the body of the angelfish.

These symptoms are an indication that there is some problem, and it is not the natural behavior of your angelfish. In that case, follow my guide above to detect the problem and sort it out.

Should You Introduce Hiding Spots in Your Aquarium?

Many aquarium owners think that by eliminating the hiding spots in the aquarium, they will be able to make angelfish active once again. However, this can be a big mistake.

The natural habitat of angelfish in the amazon basin consists of plenty of hiding spots. That is why, if you remove them, the angelfish will always be under stress. It will try to hide behind the filter or other such spots available. Also, this continuous stress will undermine the growth of the angelfish.

Instead of eliminating the hiding spots to make angelfish active, it is advisable to work on the root cause of the problem and remove it.

As for adding hiding spots to your aquarium, you should at least add a few of them like:

  • Rocks
  • Driftwood
  • Vertically floating plants

It will ensure that you can mimic the natural habitat of angelfish, and therefore, they will not be under stress consistently. However, when you do put these in the tank, make sure you do so gently without hassling movements.


Angelfish tend to hide. However, in some cases, hiding behavior can indicate a problem. For example, if your angelfish hides consistently and seldom comes out, it is time to find out a few reasons why it might be behaving in such a manner.

I, for one, have observed angelfish in my aquarium pretty carefully over the years and have devised a list of reasons for this behavior. You can use my guide above to identify the problem and eliminate it. Remember that if the angelfish suffers due to this cause for an extended period, its health can take a toll as well. 


  1. https://en.wikipedia.org/wiki/Hard_water
  2. https://pets.thenest.com/test-water-hardness-aquariums-12161.html
  3. https://en.wikipedia.org/wiki/Sphagnum
  4. https://www.algone.com/adjust-ph-aquarium
  5. https://www.theaquariumguide.com/articles/an-overcrowded-aquarium
  6. https://aquariumtidings.com/angelfish-tank-mates/
  7. https://www.fishlore.com/aquariumfishforum/threads/angelfish-hiding-all-the-time-now.292578/
  8. http://www.soest.hawaii.edu/SOEST_News/….pdf