Hammer Coral Care: The Complete Guide

Hammer coral’s array of colorful polyps bobbing in the current add an aesthetic to your fish tank that strikes a cord with observers. An alien-looking creature, Hammer coral is surprisingly simple to care for when you take the time to understand it. When your reef tank is stable, keeping a Hammer coral is easy and your tank will sing in delight at the newest addition.

Basic Hammer Coral Facts

Hammer corals are native in the Indo-West Pacific; found in Fiji, the Solomon Islands, Tonga, Thailand, and on the Great Barrier Reef. Hammer coral is LPS, or large polyp stony, characterized by the skeletal body and large elongate polyps. They used to be far more widespread, but they have been classified as vulnerable on the Endangered Species List.


This coral is from warm tropical waters and will need a relatively warm water temperature. Between 74 and 78 degrees Fahrenheit keeps them happily extending their polyps. They are rarely found deep in the water, as they need some light for their zooxnathellae to photosynthesize.

The degradation of the Hammer coral’s natural habitat and the overharvesting of this coral for aquariums has caused the costs of this coral to rise. They will run anywhere from $20-$40 for a small frag to $75-$150 for a decent-sized colony. Like all coral, the Hammer will become more expensive the prettier and more desirable the color variations are.


Hammer coral is a breed of Euphyllia, officially classified as Euphyllia Ancora. This coral comes in colors ranging from orange to blue and gray to purple, with the body usually darker than the tips of the coral. Their tips will glow under your aquarium lights due to a slight or partial infection of the viral green fluorescent protein. This is a highly sought-after trait for home aquarists.

The Fluorescent tipped Hammers are probably one of the prettiest LPS corals that can be kept in a home aquarium. Plus, they look the best when illuminated with dimmer lighting, but we will get to that further.

The tips of the Hammer also can have one of three different characteristics. They can be “T”-shaped, the traditional look associated with a Hammer. They can also be curved, which causes the coral’s tips to pull up slightly at each edge, giving the coral a distinct anchor look. They can be round, which looks like bubbles at the end of each polyp. The curved look is where the term anchor coral came from to describe this Euphyllia.


Like most of the Euphyllia, Hammers can be very aggressive and will actively harm any corals in the area where they want to be. It will extend long, sweeper tentacles that can reach far from its body. The nematocysts at the tips will deliver a sharp sting to an unsuspecting coral neighbor. They are incredibly territorial.

They can whack the unwanted coral until they kill it if the tank owner is not aware and careful. Hammers use this as a defense in the wild to ensure their survival and eliminate competition for food. Hammers and other Euphyllia corals can reside next to each other because they are immune to the stinging nematocysts on each other’s sweepers.

Hammer Corals in Your Tank

Like most coral, the Hammer coral is on the sensitive side. It doesn’t like sudden fluctuations, though it will tolerate more than some coral if the values change slowly, as opposed to a sudden shift. Remember that the parameters of your tank keep your marine habitat healthy, so make sure to take the utmost care in your tiny recreation of the ocean.

Water Parameters

Water Parameters are the number one priority when keeping saltwater fish, and even more so with coral. These critters don’t take too kindly to the water shifting suddenly. They require specific parameters to survive and be healthy and well-adapted in the aquarium. The most critical parameters for LPS coral are:

  • Salinity
  • pH
  • Phosphate
  • Alkalinity (hardness)
  • Nitrates
  • Other elements and minerals

If you can keep these parameters, then you will find success in your saltwater tank. If you cannot, then there is little likelihood that your expensive adventure into the underwater world will succeed which leaves you with negative, salty feelings.

Salinity and pH

Salinity is significant. It is, after all, a saltwater tank. Some will say that you can keep your tank at a specific gravity anywhere from 1.022 to 1.025. Truthfully, it is better to keep the tank right at 1.025, with little fluctuations. Salinity that is too low or too high can be disastrous. You can prevent this with an auto-top-off system in your sump. This prevents the build up of salt and other elements due to evaporation.

pH is the other critical level that you need to be aware of. Without proper pH, these animals cannot survive. The appropriate pH for this Hammer coral will sit between 8.1 and 8.3, which is slightly basic and lends to the alkalinity the tank should also have.


Alkalinity is also referred to as hardness and is measured using the degrees of hardness represented by dKh. The proper alkalinity should sit in the range of 8-11 dKh. Proper alkalinity will prevent pH shifts, alkalinity burns, coral bleaching, and tissue loss. In addition, the equipment on the tank will run better, and the alkalinity is vital to the formation of the hard coral skeleton creating the base of the Hammer coral.

Phosphates and Nitrates

These are two tank byproducts that can adversely affect the coral and the fish residing in the environment. The nitrates are the waste products that have gone through the ammonia cycle and should be kept low, though sometimes too clean of a tank can be detrimental. Nitrates should be kept under 30 ppm.

Phosphates can also cause adverse effects on a tank and phosphate can keep the coral from growing. This is why the levels should remain less than .1 ppm in a healthy tank. Again, you want a little phosphate to encourage growth, but letting it get out of hand is never good.

Calcium and Magnesium

These two are the building blocks of the skeletal structure of the Hammer coral. The calcium becomes calcium carbonate and is used to build the base. The magnesium helps the coral to absorb and utilize the calcium from the tank water. This is the same way people need magnesium to absorb calcium properly. Calcium should be around 400 ppm or even a bit higher at 450 ppm, depending on the reef you are keeping, and magnesium should be between 1250 and 1350 ppm.

Tank Environment

Water is not the only important thing in the tank. These things make ocean water livable for marine life, making the aquarium a home where the creatures are happy and thriving.

Tank Size and Temperature

Hammer corals are territorial and aggressive, so they like a lot of room. There needs to be a certain amount of space in your tank for them. This will be true of any tank unless you are doing a Euphyllia-only tank, which is beautiful but not always practical. If you have a mixed reef and fish tank or coral tank, you will need at least 50 gallons for a Hammer coral.

This allows enough space to house the Hammer if it needs to be separate. This also allows you to regulate the tank temperature a bit better. Hammer coral likes a warm, tropical temperature. Between 74 and 78 degrees Fahrenheit is very agreeable for them. Fifty gallons also allows you to acclimate the coral to the lighting parameters and flow as needed.


Though this is not as critical for the Hammer as other Euphyllia, but the substrate with a Hammer should be nice and sandy. This way, if it is necessary to place the coral directly onto the sand, the bottom of the tank will be acceptable to this LPS.


Hammer corals do not need too much light. Anywhere from 80 to 120 PAR, in LED terms. You might want to consider the switch if you’re not using LED. LED has longevity, and good light can be adjusted to the right spectrum to highlight the best in your coral. Plus, you can set the light for different zones in a mixed tank.


Hammer corals are fans of moderate current. They like enough strength to jostle their polyps and help keep them afloat. But if the flow is too high, they will scrape against the coral skeleton and get damaged or even tear off, leaving them prone to infection. It is best to start low and gradually increase it until the polyps fully extend and seem the happiest.


Hammer corals are not as particular about their placement as some corals are. If you remember avoiding extremes, you should be okay with placement wherever you like. If the coral is bleaching it might need less light intensity. If you see the polyps non-extended, it may require less shade. Move it around by small increments, and you should eventually see where the coral looks plump and full, and sways happily in the current.

Water Changes

Water changes will always be a part of aquarium maintenance for the hobbyist, so you should try to minimize the stress on the creatures in the tank. Do not exchange more than 25% of tank water at a time; if you do that much, shoot for once every three to four weeks. You may also choose to do 10-15% bi-weekly, which will minimize the stress further and help ensure no sudden shifts in parameters.


So we all know that there are reef-safe fish, and then there are fish unsuitable for the aquarium. The reef-safe fish are gentle with the coral and even sometimes clear parasites off of them. Clownfish are often found hosting Hammers without causing damage, unlike when they host the Hammer’s cousin, the Torch coral.

These are reef-safe for the Hammer:

  • Anthias
  • Blennies
  • Gobies
  • Tags
  • Clownfish
  • Cardinal fish
  • Wrasses
  • Damsel fish

It would be best if you avoided these fish as they have a tendency to want to take nibbles of the Hammer and can end up causing severe damage:

  • Angelfish
  • Parrotfish
  • Butterflyfish
  • Groupers
  • Pufferfish
  • Triggerfish
  • Hermit crabs
  • Emerald crabs
  • Peppermint shrimp


Hammers share a symbiotic relationship with zooxanthellae algae. Therefore they do not need to be fed as the zooxanthellae will provide them with food. This is the special relationship that all coral share with zooxanthellae. You might want to feed to encourage growth but be warned that Hammers are the least likely to want to partake in extra feedings.

Feed meaty foods like Mysis shrimp, enriched brine shrimp, or copepods, but probably no more than once every week or ten days. Target feeding is also the best choice for Hammer coral so they can grab ahold. Don’t forget to turn off the flow for the duration of feeding.

Diseases and Other Problems

Hammer coral can be more prone to diseases and issues than some coral. They are susceptible to parasites and share the common problem of Euphyllia of the polyps not extending.

Brown Jelly Disease

This is a known cause of concern for all euphoria and coral in general. The polyps will become dull and look to be coated in a brown, jelly-like substance, and then they melt away. This is dangerous because if you’re not proactive and quarantine or remove the affected piece, the entire tank can get it and be gone in a flash.


Hammer Coral is notorious for parasites, and besides aiptasia, Aceol worms, also known as brown flatworms, absolutely love Hammer coral. They live in the base and slowly devour the coral. However, a quick coral dip can rid the offending piece of this problem. Ensure you visually inspect new coral before it is added to the tank and along with a dip, and you will most likely avoid these worms.

Euphyllia Specific Problems

All Euphyllia species share some common issues. Bleaching and non-extension of polyps. A lot of similar things also cause them. Both known issues can be caused by suddenly shifting water parameters or improper placement in the tank. Adjusting these can fix any problems you see.

Non-extension of polyps is caused by a flow that is too strong, and bleaching is often caused by lighting that is much too intense, causing the expelling of the zooxanthellae algae. Adjusting these should fix the issue if it isn’t caused by water parameters being wrong.

Stop! Hammer Time

Hammer coral is a stunning creature and a fabulous addition to a tank. They are reasonably sturdy and gorgeous, fulfilling many needs of both the novice and expert reef-keeper alike. They can create incredible movement in an aquarium. Don’t discount this unassuming coral; Hammer coral can drive your tank from pretty nice to spectacular.