Sand anemone (Heteractis crispa blue tip)

Choose it for an experienced marine setup

The Sand anemone is an Indo-Pacific sea anemone also known as the sebae anemone, leathery sea anemone, long tentacle anemone and purple tip anemone. This advanced-care marine invertebrate suits experienced keepers who can maintain stable saltwater chemistry, suitable lighting and safe clearance around its tentacles. The sebae anemone species summary places it in the Indo-Pacific, giving useful natural-history context for an animal that belongs in a saltwater aquarium rather than a freshwater or brackish system.

The World Register of Marine Species now lists it as Radianthus crispa. The familiar binomial Heteractis crispa identifies the same animal throughout its care fields and product name.

Understand what makes an anemone different

An anemone is a single-polyp marine invertebrate rather than a fish or a skeleton-building coral. It obtains nutrition through photosynthesis by internal zooxanthellae and through prey capture. Its tentacles can sting and hold animals that come within reach, while the anemone itself may change position when conditions or placement do not suit it.

Those characteristics make the aquarium’s lighting, water stability, open clearance and livestock plan inseparable. A visually attractive gap between rocks is not automatically a safe position if the animal can reach a coral, intercept a slow-moving fish or move into a crowded area. Plan the whole surrounding zone, not just the point where you first place its base.

Decide whether the care level fits

This is an advanced-care choice for an experienced marine keeper. Success depends on a mature biological filter, stable saltwater chemistry, appropriate lighting, careful feeding and regular observation. The right keeper is prepared to test several water values, maintain them within narrow targets and alter the livestock layout if the animal moves.

Understand the animal and the offer

One purchase supplies one Sand anemone. Use purchase quantity to choose how many animals you want. Plan the aquarium around the animal’s fully extended reach and the clearance it may need after settling.

Sex is guaranteed only when the selected option explicitly states male or female. This Sand anemone listing has no sex-guaranteed option.

Allow for natural visual variation

The gallery images are representative of this type of animal rather than photographs of the exact animal supplied, so colours can look slightly different from the live animal.

Use the image to understand the general anemone form, including the dense spread of slender tentacles, rather than as a promise of an exact shade or tip pattern. Colour and extension should also be considered alongside behaviour and water quality after introduction because darkening, bleaching, brown dead tissue, reduced extension and failure to open are among the changes that need attention.

Plan before choosing related livestock

Complete the aquarium and compatibility plan before purchase. Check the swimming habits of fish, the location of corals, the behaviour of any clownfish and the space the anemone could occupy if it moves. Choosing livestock independently and trying to create clearance afterwards can leave no safe route for the anemone or its neighbours.

You can browse the wider marine invertebrates collection when planning the aquarium, but treat each animal as a separate husbandry and compatibility decision. A shared marine category does not make two animals suitable tank mates.

Start with the water and space plan

OATA’s anemone guidance gives broad group targets of 24–26°C, pH 8.1–8.3 and salinity 1.023–1.026. Use these figures as the routine planning range while checking that every other animal in the aquarium can share it.

OATA recommends an aquarium of at least 80 litres for most anemones because smaller systems may undergo rapid chemistry changes. Treat that figure as a planning floor for most members of the group, not an automatic final fit for every animal. Larger anemones need larger aquariums, and the footprint must leave enough clearance around the tentacles.

Make stability the first buying test

Do not judge readiness by water volume alone. The aquarium also needs an established biological filter, suitable lighting, sufficient water movement and repeatable test results. An 80-litre system with changing salinity or detectable ammonia is a poorer choice than a larger, mature aquarium that consistently stays within target.

Choose this animal only when you can maintain the full set of values, not merely temperature and salinity. Ammonia and nitrite must remain at zero, while nitrate and phosphate must stay below their stated maxima. Calcium, magnesium and carbonate hardness also form part of the saltwater plan even though anemones do not build a calcium carbonate skeleton.

Mature the aquarium before introduction

A mature marine aquarium is one in which the biological filter can process waste without allowing ammonia or nitrite to accumulate. Anemones can be stressed by even small amounts of either compound, so introduction should wait until both test at zero and the rest of the chemistry remains steady.

The RSPCA’s aquarium filtration guidance explains the biological sequence: beneficial bacteria convert toxic ammonia into nitrite and then into the safer nitrate. The filter must be established and maintained so this process continues as livestock and feeding add more waste.

Use readiness tests rather than a calendar

A single acceptable test is only a snapshot. Repeat testing through normal lighting, feeding and maintenance routines so you know the aquarium can hold its values during ordinary use. Correct the cause of any instability before introducing the animal rather than relying on a large adjustment at the last moment.

Increase livestock slowly

Add livestock gradually because the beneficial bacterial population has to respond whenever waste and feeding increase. Adding too many animals too quickly can create new tank syndrome, in which the filter lacks enough nitrifying bacteria to process the extra waste. The result may be unhealthy ammonia or nitrite levels capable of making an anemone ill or causing its death.

Keep the filter operating throughout preparation. If maintenance temporarily reduces flow or removes filter media, complete that work and confirm normal operation before introduction. The aim is a settled system whose normal routine is already working, not an aquarium undergoing major changes while the anemone tries to attach and adjust.

Control water quality with repeatable actions

Use the target table as an operating range, not as permission to let readings swing from one edge to the other. Anemones need stable marine conditions, and smaller aquariums can change quickly. Measure values consistently and investigate movement before a limit is crossed.

Read each test as a decision

• Ammonia or nitrite above zero: treat the aquarium as unsuitable for introduction. If either appears after the animal is settled, test again, check filtration and reduce the waste pressure rather than adding livestock.
• Nitrate approaching 40 mg per litre: perform the scheduled partial water change, check for trapped waste and review uneaten food. The stated limit is not a target to maintain.
• Phosphate approaching 0.05 mg per litre: check feeding residue and maintenance before the value passes its maximum.
• Salinity outside 1.023–1.026: restore the aquarium to the target carefully and identify why it moved before introduction.
• pH outside 8.1–8.3: examine the wider chemistry, including carbonate hardness, rather than treating pH as an isolated number.
• Calcium, magnesium or carbonate hardness outside range: bring the marine-water plan back into balance and retest before making another change.

Record results in the same units each time: carbonate hardness is 8–12°dKH, calcium is 380–450 ppm and magnesium is 1250–1350 ppm. Keeping a short dated log makes gradual movement easier to see than relying on memory.

Change one controllable factor at a time

When a reading moves, begin with clear causes such as missed maintenance, excess food, blocked filtration or a recent increase in livestock. Several simultaneous changes make it difficult to identify what restored the value and can replace one instability with another.

Test again after corrective maintenance and before adding more food or animals. If the anemone is already present, combine the numbers with observation: reduced tentacle extension, failure to open, movement after a settled period, bleaching or a gaping mouth outside defecation all justify an immediate water-quality check.

Keep filtration and flow reliable

A filter is essential for an anemone aquarium. Marine filtration may use live rock with sufficient water flow, an internal or external filter, or a sump-based filter. Choose a method that can operate continuously and be maintained without repeatedly disrupting the biological bacteria that process waste.

Protect the biological filter during cleaning

Check the filter regularly and clean it before blockages reduce performance. Never rinse biological media under the tap because chlorine or chloramine may kill the established bacterial population. During a partial water change, rinse the media lightly in the removed aquarium water instead. This preserves more of the bacteria while loosening accumulated debris.

After cleaning, confirm that the filter has restarted normally and that water movement has returned to its usual pattern.

Use a protein skimmer as additional control

A protein skimmer can help maintain water quality by removing dissolved organic waste before it breaks down into more harmful substances. Clean it regularly so its performance does not decline. A skimmer supports the maintenance plan; it does not replace biological filtration, water testing or partial water changes.

Make flow part of the placement decision

Live rock used for filtration needs sufficient water movement, and the anemone may relocate if its position does not suit it. Observe the animal’s extension and position after introduction rather than assuming the first placement is permanent. A settled animal that later detaches and moves is a health and husbandry signal, particularly if the change occurs alongside worsening water tests or reduced feeding.

Check the full flow path whenever pumps, rockwork or filtration are changed. A modification elsewhere in the aquarium can alter the conditions reaching the anemone. Complete major filtration and layout work before introduction whenever possible so the animal is not repeatedly asked to settle into a changing environment.

Match lighting to photosynthetic care

Anemones obtain part of their nutrition through photosynthesis carried out by zooxanthellae living within their tissues. Lighting is therefore a nutritional requirement rather than decoration. OATA advises that anemones generally require moderate to high light, although the precise requirement and placement vary among species.

Plan the light before choosing a position

Use a marine lighting system capable of supporting a photosynthetic anemone and include the intended position in the plan. Do not select a location solely because it makes the animal easy to see. The position must combine appropriate illumination with stable water, workable flow and enough clearance from animals that could be stung.

Rockwork and neighbouring livestock can change how much light reaches a position. Consider shading from overhangs and the space occupied by corals before introduction. If the anemone changes location, reassess the light and compatibility around its new position rather than moving unrelated livestock without a plan.

Use the animal’s appearance as an alert

Watch for reduced tentacle extension, failure to open, darkening, bleaching or brown dead tissue. These signs do not identify one cause by themselves, so pair the observation with immediate checks of temperature, salinity, pH, ammonia, nitrite, nitrate and the lighting arrangement.

A change in colour is more useful when compared with the animal’s own settled appearance than with a representative gallery image. Make a simple visual note after settling, including extension, mouth position and where the base is attached. That gives you a practical baseline for spotting change without expecting every animal to show the same shade.

Keep light and feeding in the same nutrition plan

Photosynthesis does not remove the need for prey-based feeding. Conversely, feeding does not make unsuitable lighting acceptable. Plan both routes together: maintain appropriate moderate-to-high illumination for the group, then offer manageable food items through the tentacles while controlling waste.

Feed through the tentacles without waste

Anemones combine photosynthesis with prey capture. Suitable offered foods include pellets or larger frozen items such as lance fish, cockles or mussels. The item must be small enough for the animal to accept; an oversized piece may be rejected and left to break down in the aquarium.

Use a response-led feeding routine

1. Choose one manageable food item rather than a large portion.
2. If using a frozen food, prepare it for feeding and keep the portion small enough for the anemone to handle.
3. Place the item into the tentacles rather than dropping food elsewhere in the aquarium.
4. Allow the tentacles to recognise the item and move it towards the mouth.
5. Watch for acceptance or rejection and remove uneaten residue before it contributes to waste.

The tentacles and mouth provide the clearest immediate feedback. A recognised item is moved towards the mouth. Repeated rejection, reduced intake or constant expulsion of stomach contents is a reason to stop adding food and check the animal’s condition and water quality.

Prevent overfeeding

Do not offer extra food simply because the previous item disappeared from view. Overfeeding can leave uneaten material that breaks down and releases toxic waste. Use acceptance, the absence of residue and stable ammonia, nitrite, nitrate and phosphate readings to guide the next feeding decision.

If a piece is rejected, consider portion size before changing the food type. The group guidance specifically warns that pieces which are too large may be refused. A smaller item gives the animal a more manageable feeding task and puts less waste into the aquarium if it is not accepted.

Respond to declining intake

Reduced feeding should be read alongside tentacle extension, mouth position, movement and colour. Begin with water tests and a check of lighting and filtration. Do not mask a declining response by repeatedly presenting different foods, because every rejected item adds avoidable organic load to the system.

Keep feeding tools and actions gentle around the tentacles. Place the food where the animal can grasp it and allow the anemone to complete the transfer itself rather than forcing food into the mouth.

Acclimatise without adding bag water

Prepare the aquarium before the animal arrives. Use OATA’s anemone targets to confirm that temperature, salinity, pH, ammonia and nitrite are within range, make sure the filter and lighting operate normally, and clear the intended position from nearby animals that could be stung.

Follow the store acclimatisation steps

1. Be present to receive the parcel so the live animal is not left unattended.
2. Start filming before opening the parcel, showing it still sealed with the outer box visible. Continue filming as you open it and show the animal still inside the sealed bag.
3. Float the bag in the aquarium for 20–30 minutes.
4. Release the animal after floating, and never pour the bag water into the aquarium.

These steps come from our delivery and Live Arrival Guarantee policy. Film every delivery continuously from the sealed parcel onwards. Keep the video with your order details and send it if you need to make a Live Arrival Guarantee claim.

Do not combine arrival with other disruption

Avoid carrying out major filter cleaning, rockwork rebuilding or a large livestock addition during the same introduction period. Beneficial bacteria need time to respond when livestock and feeding increase, and changing several parts of the system together makes any resulting water-quality movement harder to diagnose.

Once the anemone is released, treat the chosen position as a starting point rather than a permanent placement. It may move while selecting a location. Keep the wider route clear enough to reduce immediate conflicts with corals and slow-moving fish, then monitor extension, attachment, mouth position and colour.

Use the first observations as a baseline

Note whether the mouth is closed, how far the tentacles extend and where the base settles. Continue testing rather than judging success from extension alone. An animal can change appearance while the water is moving towards an unsafe value, so behaviour and chemistry should always be interpreted together.

Maintain the system every week

Make a 25% partial water change at least once every week. Use a siphon to remove solid waste from the gravel where practical, then use some of the removed aquarium water to rinse filter media lightly when cleaning is needed.

Use a fixed maintenance sequence

1. Observe the anemone before disturbing the aquarium.
2. Test ammonia, nitrite, nitrate, pH and the other marine values in the water plan.
3. Complete the 25% partial water change.
4. Remove visible solid waste and uneaten food.
5. Check the filter for blockage and rinse media only when needed.
6. Clean the protein skimmer regularly if one is used.
7. Restart and confirm all equipment before leaving the aquarium.

Testing before the water change tells you what developed during the normal week. Testing again after a concerning result shows whether maintenance restored the value. Keep dated results so a slow rise in nitrate or phosphate is visible before either reaches its maximum.

Know the changes that need action

No single sign identifies a complete diagnosis. Start with the measurable factors: ammonia, nitrite, nitrate, phosphate, temperature, salinity, pH, carbonate hardness, calcium and magnesium. Check filtration, lighting, flow and feeding residue at the same time.

If the signs persist after water and equipment checks, contact us for further guidance. Do not begin an improvised treatment in the display aquarium, because the first task is to identify and correct any husbandry pressure affecting the animal.

Use a first-month checkpoint plan

The first month should establish whether the aquarium routine remains stable with the added animal. The goal is not to force a particular position or appearance; it is to recognise the animal’s settled pattern while confirming that filtration, feeding and maintenance continue to hold the target values.

On the first day

• Confirm continuous filming began with the sealed parcel before it was opened.
• Confirm the bag was floated for 20–30 minutes and transport water stayed out of the aquarium.
• Record the initial position, mouth condition and degree of tentacle extension.
• Check that nearby corals and slow-moving fish remain beyond tentacle reach.
• Confirm filtration, flow and lighting are operating normally after introduction.

During the first week

• Test ammonia and nitrite closely enough to detect any response to the additional waste load; both must remain at zero.
• Watch whether the animal attaches, opens and begins to establish a consistent position.
• If it moves, reassess the new area for coral contact and fish exposure rather than assuming the original clearance still protects the aquarium.
• When feeding, use one manageable item and watch for acceptance before planning another offering.

By the first monthly review

• Compare the latest water log with the initial readings, paying particular attention to nitrate and phosphate trends.
• Review whether weekly 25% water changes and normal filter maintenance are keeping the system stable.
• Compare colour, tissue, mouth position, feeding and tentacle extension with the animal’s settled baseline.
• Check that its chosen location still leaves adequate space from corals and vulnerable fish.

A stable month is a reason to continue the routine, not to relax it. Keep the same water ranges, weekly water change, careful feeding and compatibility screening in place. If a later equipment, livestock or rockwork change alters the animal’s position or behaviour, return to the same observation-and-test sequence used during introduction.

Screen fish before combining them

An anemone can sting and capture animals that come within reach. Compatibility therefore depends on how a fish moves, where it spends its time and whether it may damage the anemone. A general marine label or peaceful temperament is not enough to make the decision.

Avoid vulnerable or damaging fish

Avoid slow-moving fish and fish that spend much of their time near rockwork, such as dragonets, because anemones are likely to prey on animals they can catch. Also avoid puffers and triggerfish because members of those groups may damage anemones.

Check clownfish by species

If the purpose is to house clownfish with the anemone, confirm that the chosen anemone can host the particular clownfish species. An incompatible pairing may result in the clownfish being stung or eaten. An anemone is not essential to keeping clownfish, so do not force a pairing merely to create a familiar display.

Observe the aquarium layout as part of this decision. A fish that usually stays clear may be channelled towards the tentacles by rockwork, feeding positions or narrow swimming routes. Leave a practical path around the anemone’s whole reach, including any area it could occupy after moving.

Compatibility with an unlisted fish remains uncertain until its swimming zone, feeding behaviour and tendency to bite anemones have been assessed. Arrange a stocking and compatibility assessment before combining animals whose behaviour does not clearly pass those screens.

Leave room around corals and anemones

Corals can share an aquarium with anemones when there is enough room to prevent stinging. Measure usable separation around the extended tentacles rather than spacing livestock only from the centre of the anemone. The animal may change position, so clearance must still work if it settles somewhere nearby.

Map the contact zone

1. Mark the intended anemone position and the surrounding area its tentacles may occupy.
2. Identify corals that cannot move away if the anemone relocates.
3. Check whether rockwork creates a route towards those corals.
4. Leave open separation rather than relying on a narrow visual gap.
5. Review the map whenever the animal moves or the aquascape changes.

Do not treat attachment as proof that the position is permanent. Movement by an anemone that has been settled for some time is also a health warning, so respond in two ways: protect neighbouring livestock from contact and test the aquarium conditions that may have prompted the change.

Plan around one before considering more

Begin the space plan with one animal. Consider an additional anemone only after accounting for the mature reach, movement zone and stinging clearance of each animal, as well as the extra waste and feeding added to the filter. Purchase quantity chooses the number supplied; it does not establish that multiple animals should share one aquarium.

There is no universal tank-mate list. A suitable decision combines water-range overlap with behaviour and physical space. Every proposed neighbour must tolerate 24–26°C, pH 8.1–8.3 and salinity 1.023–1.026, but matching water alone is insufficient if it can be caught, sting the anemone, damage it or become trapped within its movement zone.

Reassess after every layout change

Moving a coral, adding rock or changing flow can turn a previously clear route into a contact point. Observe tentacle reach after the change and confirm that slow-moving fish still have safe routes through the aquarium. Make compatibility a continuing maintenance decision rather than a one-time check made on introduction day.

Answer common buying and care questions

How big does the Sand anemone get?

Plan its space around the animal’s fully extended tentacle reach and the area it may occupy if it moves. Leave open clearance from corals and vulnerable fish rather than fitting it to a fixed decorative gap.

What size aquarium does it need?

OATA’s group guidance recommends an aquarium of at least 80 litres for most anemones because smaller systems may experience rapid chemistry changes; larger animals need larger aquariums. Use a mature, filtered marine setup with sufficient tentacle clearance.

How many Sand anemones should I keep together?

Begin with one animal. Consider another only after allowing for each anemone’s extended reach, movement zone, stinging clearance, feeding and added waste load.

Is the Sand anemone suitable for beginners?

It is best suited to experienced marine keepers. OATA advises that anemones can have specific requirements, including stable water chemistry, suitable lighting, careful feeding and compatibility planning.

What does it eat?

It obtains nutrition through photosynthesis and prey capture. Offer a manageable pellet or a small frozen item such as lance fish, cockle or mussel by placing it in the tentacles, and remove rejected food before it breaks down.

What temperature and pH does Heteractis crispa need?

OATA’s group guidance gives 24–26°C, pH 8.1–8.3 and salinity 1.023–1.026 for anemones. Keep ammonia and nitrite at zero mg per litre, nitrate at no more than 40 mg per litre and phosphate at no more than 0.05 mg per litre.

Is this animal aggressive or likely to nip fins?

It uses stinging tentacles to capture animals within reach and may move around the aquarium. Avoid slow-moving fish and fish that spend much of their time near rockwork because they are vulnerable to predation.

Which animals can it live with?

Avoid slow-moving fish, rockwork-dwelling fish such as dragonets, puffers and triggerfish. Check clownfish compatibility by species, and keep corals only when there is enough room to prevent stinging if the anemone moves.

How does the Sand anemone arrive alive in the UK?

Someone must be present to receive it. Film every delivery continuously from the sealed parcel, showing the outer box as it is opened and the animal still in the sealed bag; then float the bag for 20–30 minutes before release and never pour the bag water into the aquarium.

Check the care and identity references

• World Register of Marine Species — accepted-name and taxonomic-family placement.
• Sebae anemone species summary — common names and Indo-Pacific natural history.
• OATA: How to look after anemones — water, aquarium, feeding, maintenance and compatibility guidance for anemones.
• RSPCA aquarium environment guidance — biological filtration and waste processing.