Anemone Shrinking: Causes, Effects, And Prevention Strategies!

Anemone shrinking is a common phenomenon observed in both marine and aquarium environments. Often, anemones shrink or deflate due to various stressors, such as proximity to other aquatic creatures in the tank or changes in environmental conditions like temperature and lighting.

While anemone shrinkage can be normal and not a cause for alarm, understanding the factors that contribute to this process may help aquarium owners maintain a healthy environment for their anemones.

Normal shrinkage can occur as part of the anemone’s natural behavior, such as when it’s eating, excreting waste, or responding to changes in lighting. However, underlying issues, such as problems with feeding, infection, and damage can also lead to an unnatural deflated appearance.

By familiarizing oneself with the reasons behind natural and unnatural anemone shrinkage and recognizing the signs of distress, one can take the necessary steps to prevent long-term damage or stress to their aquatic pets.

Key Takeaways

  • Anemone shrinkage is a common yet generally harmless phenomenon
  • Environmental factors and feeding issues contribute to anemone shrinking
  • Recognizing these factors is essential in maintaining a healthy environment for anemones

Causes Of Anemone Shrinking

An anemone in a reef tank

There are a number of common causes of anemone shrinking that even experienced anemone keepers can have problems with. These issues can cause natural and unnatural shrinkage in your anemone and some people can struggle to distinguish the difference between the two.

As a general rule of thumb, natural shrinking usually results in the anemone shrinking by 25-50% for less than a day. Anything more than that that lasts for longer than two days has a high chance of being unnatural shrinking due to a problem.

You will know your tank better than anyone though and depending on your setup, it may be totally normal for some of your anemones to shrink more than others. This is why many people use the “anything out of the ordinary” method to try and identify problems in their tanks.

Stress Factors

Stress can be a common cause of anemones shrinking

Anemones are delicate creatures that can be affected by various stressors in their environment causing them to shrink. Some common factors that contribute to stress include fluctuations in water parameters like pH, temperature, salinity, and ammonia levels.

Anemones can also become stressed from physical disturbances, such as being accidentally poked or having objects dropped on them.

One very common cause of stress that is often overlooked is vibrations in their tank. These vibrations can be caused by the tank being placed in a high trafficed area in your home, loud music/TV, and doors being slammed.

Most anemones will make a full recovery from being stressed within days of the cause of their stress being removed from their environment.

Feeding Issues

Feeding Issues can cause anemones to shrink due to a number of reasons

Starvation is one of the main reasons for anemone shrinking. Proper feeding is essential for their growth and health, but overfeeding can also lead to negative consequences.

An anemone might deflate due to expelling trapped water and waste food items, which is a normal behavior in response to overfeeding.

Some beginners often overlook the need to feed their anemone to keep it healthy and presume that their tank setup will provide all their anemone needs but this is difficult to achieve.

Here are some great food sources that work well with a wide range of anemone:

  1. Zooplankton: These tiny organisms are a primary food source for many anemones.
  2. Mysis Shrimp: These small shrimp are a commonly used food source for anemones, particularly in aquariums.
  3. Brine Shrimp: Brine shrimp (including newly hatched Artemia) can also be fed to anemones.
  4. Fish Fry or Small Fish Pieces: Smaller pieces of fish, or young fish, can also be a part of their diet.
  5. Chopped Seafood: This can include items like squid, mussels, or clams, all cut into appropriate sizes for the anemone to consume.
  6. Krill: Many species of anemones will consume krill, either whole or chopped, depending on the size of the anemone.
  7. Copepods: These tiny crustaceans are another natural food source for anemones.
  8. Phytoplankton: Although not a primary food source for anemones, some species may consume phytoplankton.

It can take weeks for an anemone to grow back to its previous size if it has shrunk due to feeding problems.

The key is to start to supplement your anemones diet with suitable foods as quickly as possible to prevent the issue getting worse and then build your anemones size up from there.

In some cases, simply increasing the magnesium and phosphate levels in your tank may be enough to correct the problem and encourage your anemone to return to its previous size.

Lighting Problems

lighting problems can be enough to cause some anemones to shrink

Anemones rely on light for their well-being, making the proper lighting system crucial in maintaining their health. Poor lighting can result in shrinkage or faded coloration.

The problem is, different types of anemones required different PAR ranges, light cycles, and types of lighting.

If you suspect that lighting is the reason behind your anemone shrinking then you will have to do some research into the specific requirements for the type of anemone you keep and its needs.

Once the lighting setup has been optimized to the needs of your anemone, you should see slight improvements within days with most anemones making a full recovery within a number of weeks.

Water Parameter Fluctuations

Water Parameter Fluctuations are another common cause of anemones shrinking

Maintaining stable water parameters is critical for the health of anemones. Poor water parameters or sudden changes in water temperature, pH, salinity, ammonia, nitrite, and phosphate levels can negatively affect your anemone.

Shrinking is a very common symptom of problems with water parameters but here are some additional symptoms to lookout for:

  1. Retraction of Tentacles: Anemones might retract their tentacles, making them look shriveled and unhealthy.
  2. Discoloration: A change in color, often fading or turning pale, may indicate a problem with lighting, nutrient levels, or water quality.
  3. Failure to Attach: If an anemone is unable to attach itself firmly to a substrate, it could signal an issue with the water parameters.
  4. Excess Mucus Production: An increase in mucus production might be a response to irritation or stress from incorrect water conditions.
  5. Sluggish Response: Anemones responding slowly or not at all to stimuli, such as food, might be struggling with improper water parameters.
  6. Lesions or Physical Damage: Visible sores or damage to the body can be signs of poor water quality or infection resulting from stress.
  7. Inability to Capture Food: Struggling to capture or consume food might be a sign of internal problems caused by incorrect water parameters.

Poor water parameters in reef tanks and marine tanks are far more common than people realize due to people often using regular freshwater test kits. You can usually get a specialist reef tank test kit for a couple of dollars more than the freshwater versions that test more parameters.

If you don’t already have a reef tank test kit for your anemone tank we would highly recommend you get one.

Depending on the specific water parameter that is out of range as well as how long it has been problematic, it may take weeks or even months for your anemone to recover. In extreme cases, your anemone may not be able to recover and it can perish even if you correct the water problems and get everything back in range.


Infection is another common reason that anemones shrink

There are a number of different types of infection that can also lead to anemone shrinking. Healthy anemones might be more resistant to infections, while those subject to stress or poor water conditions may be more susceptible to disease.

Depending on the specific type of infection, shrinking may be one of the later symptoms to show. Thankfully, discoloration and excess mucus production are both common symptoms for most types of infection in anemones giving you plenty of notice that something is wrong.

Quarantining an infected anemone can be a good idea as it helps to stop the infection spreading to other anemone in the tank.

Here are some infections that can cause problems for anemones:

  1. Bacterial Infections:
    • Vibrio Infections: These bacteria can cause tissue necrosis and are often associated with poor water quality.
    • Cytophaga: This bacterial infection can lead to lesions and degradation of tissue.
  2. Protozoan Infections:
    • Brooklynella: Though more commonly found in fish, some protozoans like Brooklynella might affect invertebrates like anemones.
  3. Parasitic Infections:
    • Nematodes: Certain types of parasitic worms might infect anemones, leading to physical damage.
    • Flatworms: Some species of flatworms might prey on or irritate anemones.
  4. Fungal Infections:
    • These are less common but can affect anemones, leading to discolored patches or lesions.

Correctly identifying the type of infection causing problems with your anemone can be a pain but is worth it as it helps you find the correct treatment. In many cases, once a suitable treatment has been dosed in your tank, your anemone will rapidly show signs of improvement.

Damage From Predators

Damage From Predators can cause anemones to start shrinking

Anemones can fall victim to damage from predators, such as fish or invertebrates, which can lead to shrinking as a defensive mechanism. Try to ensure that anemones are housed with suitable tank mates that are considered reef safe.

One thing to note is that even “reef safe” species does not mean that they will not take a liking to your anemone or corals and start eating them. This is why it is important to look for visual signs of damage to your anemone that may help you confirm that a tank mate is eating it and causing it to shrink.

It may already be too late to save the anemone if a large amount of it has been eaten or damaged.

This is probably the most difficult cause of anemone shrinking to fix as you often have to re-tank the anemone or the offending tank mate and not everyone has suitable spare tanks available.

Night-Time Shrinking

The natural day and night cycle of anemones will often result in them shrinking

Anemones can naturally shrink at night when light levels are low. This is a normal behavior that usually doesn’t indicate any underlying issue but often catches people out as some anemone can shrink by as much as 50% at night.

However, if the anemone remains shrunken for several days in a row, it is advised to investigate its environment further and address any potential problems.

An infographic on why your anemone is shrinking

How To Stop An Anemone Shrinking

An anemone after having made a full recovery after shrinking

There are some common steps you can take to try and stop your anemone from shrinking with these often helping counter most of the common causes of shrinking.

Aquarium Conditions

Maintaining suitable Aquarium Conditions will often be enough to help a shrinking anemone

It is crucial to maintain optimal aquarium conditions for your anemone when it’s shrinking. Ensure the water quality is high by regularly checking and maintaining parameters such as salinity, temperature, and pH.

Keep these elements stable and within the recommended ranges for your specific anemone species. Performing regular water changes and using an appropriate filter will also help in preserving water quality.

Feeding Practices

Offering suitable food that can nurish your anemone will often prevent shrinking

Anemones require a proper diet to stay healthy and avoid shrinking. While they don’t need food every day, it’s essential to provide ample amounts of appropriate nutrition.

Feed them a varied diet, including small pieces of fish, shrimp, or other meaty items. Monitor your anemone’s response to feeding and adjust the amount and frequency accordingly. Be sure not to overfeed or underfeed, as both can lead to stress and shrinking.

Proper Lighting

Providing Proper Lighting can help a shrinking anemone

Lighting plays a vital role in the well-being of anemones because some anemones have symbiotic relationships with algae that use photosynthesis for energy.

Ensure your aquarium has suitable lights, ideally LED or metal halide, to provide the required intensity and spectrum for your anemone. Adjust the light positioning and duration to ensure the anemone receives sufficient light without causing stress.

Regularly check and maintain your lighting system to keep it functioning efficiently and meeting the anemone’s needs.

An infographic going over 3 Ways To Stop An Anemone Shrinking

How Long Does it Take For An Anemone To Return To Normal Size

A thriving anemone in a reef tank

You have to factor in a number of different variables when trying to workout how long it will take for your anemone to return to its regular size. These include the specific issue that caused your anemone to shrink, how long your anemone was exposed to the issue, and the type of anemone you keep.

Due to this, it is very difficult to give a reliable timeframe without knowing this information with some anemones returning to their normal size within days and others taking months.

One thing that we would say is investigate any changes in your anemone as soon as possible to ensure that you have enough time to treat any potential problems. Shrinking, discoloration, and excess mucus production are all common early signs that your anemone has a problem.

Just like most things in the aquarium keeping hobby, the sooner you treat a problem, the higher your anemones survival chance will be. In many cases, treating a problem as soon as you notice it will also drastically reduce the required recovery time for your anemone to return to normal too.

Similar Posts