Euphyllia divisa, better known as the Frogspawn coral is one of the most popular large polyp stony (LPS) coral in the reef hobby alongside its sibling species, Hammer coral (Euphyllia ancora) and Torch coral (Euphyllia glabrescens).
The name Frogspawn was coined from its attractive multi-tipped tentacles that bear a striking resemblance to a mass of frog eggs. This coral species is hardy, semi-aggressive, and able to attain rapid growth spurts in favorable water conditions.
This article provides an insight into the captive care of Frogspawn corals; these consist of feeding, behavior, placement, care tips, and lots more.
Quick Notes about Frogspawn Corals
|Scientific Name||Euphyllia divisa|
|Tank size (minimum)||30 gallons (~120 liters)|
|Propagation||Easy to moderate|
|Optimal Temperature||24 – 28°C (~76°F – 83°F)|
|Optimal Salinity||SG = 1.023 – 1.025|
|Optimal PH||8.1 – 8.4|
|Optimal KH||8 – 12|
|Nitrate||Less than 20 ppm|
|Tank placement||Bottom to Middle|
|Growth Rate||Slow to moderate|
|Color Form||Brown to tan, green to yellow-green and blue (rare), with cream, pink, lavender or white visible tips at the end of the tentacles|
Origin and Taxonomy of Frogspawn Corals
Frogspawn coral is a large polyp stony coral that belongs to Euphylliidae, a family of zooxanthellate scleractinans. The coral species Euphyllia divisa was first described by Veron & Pichon in 1979. Frogspawn coral can also be referred to as Octopus coral, Grape coral, Honey coral, and Wall coral, and it is related to other renowned LPS corals, namely: Torch coral and Hammer coral.
Species: Euphyllia divisa
Habitat of Frogspawn Corals
Frogspawn coral is a species that can be found in a variety of reef regions around the world. They form colonies in reef slopes of fairly deep turbid waters to a depth of 40 m (131 ft) where they enjoy planktonic matter and indirect bright lighting.
This coral is naturally domiciled in the Indo-Pacific, Fiji, Australia, Solomon Islands, East China Sea, The Great Barrier Reef, and Ryukyu Islands.
Description of Frogspawn Corals
Frogspawn corals form large colonies with corralite walls that emerge on the outer edges, these corralites are thin and sharp-edged. Some colonies are capable of reaching up to 1 meter (3 ft) in size.
This Euphyllia species has very long tentacles when fully extended, they are covered with short branches that are tipped with multiple small rounded knobs. Another prominent feature is the presence of a flabello-meandroid skeleton.
Frogspawn coral tentacles are thick, lumpy, and long; with some branching into double skeletal or single heads, at the end of these tentacles are brightly colored tips. These polyps have a bubble-like outward appearance that resembles a mass frog spawn (frog eggs).
A variety of Frogspawn corals is the Euphyllia paradivisa known to hobbyists as the Branching Frogspawn coral. This species is endemic to the waters of the Central-Indo Pacific and American Samoa. Like Euphyllia divisa, it has very long tentacles ending with multiple tipped branches, this variety has a branching/phaceloid skeleton. Branching Frogspawn corals also grow a little bit faster and easier to frag.
The color of Frogspawn coral tentacles is usually brown to tan, green to yellow-green, and blue (rare), with cream, pink, lavender, or white visible tips at the end of the tentacles.
Behavior of Frogspawn Corals
Euphyllia corals can be quite aggressive when placed in close proximity to other corals, as they tend to battle/compete for real estate in your aquarium. Therefore they should be adequately spaced from other corals in the tank.
Frogspawn coral is hostile but not to the species in its own genus, however, corals of other genera in the family Euphylliidae are not exempted from this hostility.
As observed, the polyps extend during the day and only partially at night. Their sweeper tentacles can extend up to 25 cm in larger colonies when they witness hunger pangs, this poses a threat to nearby corals because of the powerful sting they can deliver.
Some shrimp species dwelling nearby will enjoy the protection of the Frogspawn coral tentacles by means of commensalism.
Feeding Frogspawn Corals
Frogspawn coral has a symbiotic relationship with algae hosting in their tissues, this alga is called zooxanthellae. This specialized feeding mode enables them to feed through the conversion of light into food, the zooxanthellae provide just enough nutrition to sustain itself and the coral.
Additionally, the corals will capture planktonic organisms and food particles suspended in the water column, as well as the absorption of organic matter.
Regardless of the presence and role of the photosynthetic zooxanthellae, they should also be fed live and meaty frozen food. Through supplemental or manual feeding, the corals will grow more vigorously, so don’t assume that the nutrition they get from photosynthesis is enough to make them attain rapid growth spurt and gain enormous mass.
They can be fed:
- mysis shrimp,
- vitamin-enriched brine shrimp,
- daphnia or small fish,
- reef roids (link to Amazon)
Frozen foods can be thawed to make it easier for the corals to consume them.
Tank Requirements and Water Parameters
The minimum tank size for housing Frogspawn corals is 20 gallons (80 L). Opting for a larger tank is even better as it allows for adequate spacing amongst the corals and stability of water parameters.
Water type, Temperature, Hardness, and pH:
Temperature: The optimal temperature range for keeping Frogspawn corals is between 76 – 83 °F (24 – 28 °C). Keeping the temperature constant (avoiding fluctuation) is more important than the actual temperature itself.
pH: The ideal pH level is between 8.1 – 8.4. Make sure to keep your tank from experiencing rapid swings in pH.
Hardness: Frogspawn corals will appreciate water hardness value between 8 – 12 dKH.
Although Frogspawn corals can tolerate a wide range of light intensity, including high lighting, they still prefer moderate lighting for best growth and coloration. Output from fluorescent bulbs and LED lighting are enough for the lighting and energy requirements of the corals.
Metal halides might seem like a good option, but this light source gives off too much heat that is capable of damaging the corals’ tissues.
Note: The output from LED lighting around 50 – 100 PAR value, is sufficient for the lighting needs of the corals.
Tip: Do not forget that in nature these corals are commonly attached to vertical surfaces. So, place Frogspawn corals at of an angle. If the light cannot reach their branches, they often stop growing and their head do not sprout at all.
The water flow should be moderate, not too weak or strong. It should be good enough to keep detritus from collecting on the body of the Frogspawn corals.
Ensure that the corals do not get hit by direct water flow. It may damage the corals or even make the polyps unable to extend fully.
Note: Under too low flow Frogspawn corals take on more water to inflate themselves. As a result, there is more space between tissue, it leads to the loss of the coloration, from the visual point.
Care and Maintenance of Frogspawn Corals
Endeavor to carry out partial water changes of either 20 – 25% monthly, 10 – 15% bi-weekly, or 5% weekly to maintain good water quality and replenish the required trace elements.
In addition, the corals should be inspected frequently, this goes a long way in the timely detection of any damage, infection or unusual changes in their behavior. A sick or unhealthy coral should be separated from the rest, and moved to a quarantine tank for proper treatment, this helps to prevent further spread of infections.
Regular inspection and a good water change schedule are essential in ensuring good health of the corals and optimal water chemistry. Maintain the following trace elements and compounds in the right proportions to promote the best growth conditions.
Calcium: Between 400 to 450 ppm.
Magnesium: 1,250 – 1,350 ppm
Salinity/Specific Gravity: 1.023 – 1.025
Strontium: 8 – 10 ppm
Nitrates: < 1 ppm
Phosphate: < 0.05 ppm
Ammonia: 0 ppm
Placement in the Tank
Positioning the Frogspawn coral should be subjected to three factors:
- light intensity,
- water flow and
- proper spacing to curb aggression.
A best practice in housing Frogspawn corals is to abide by the 6-inches (15 cm) rule. Place other corals at least 6 inches away from Euphyllia divisa. An exception to this rule is with other similar Euphyllia species like the Hammer corals, as they will not be harmed by the sweeper tentacles of the Frogspawn coral.
Note: Even though Torch corals Frogspawn corals are different species of the same genus. Torch corals can be too aggressive towards Frogspawn corals. It is not recommended to keep them together as they tend to compete with other corals for space in the reef tank.
The placement of the corals should be subjected to an exercise of trial and error in different areas of the tank till you locate a pleasant spot, they will extend their polyps fully and feed properly when they are situated in a comfortable place.
Avoid placing the corals in a spot with very fast or direct water flow, this can cause the polyps to retract and hamper on its ability to filter-feed.
Potential Problems Associated with Frogspawn Corals
Brown jelly infection: This is a common disease for corals. It is characterized by a jelly-like brown mass that appears to be floating on the surface of the coral. Brown jelly disease is caused by poor water quality or tissue damage, it can lead to rapid tissue necrosis and it is capable of spreading to other corals in the tank.
Solution: Brown jelly disease can be treated using a broad-spectrum on the infected areas. You should remove the sick colony from the main tank, scrub off and siphon any visible brown jelly. Afterward, treat the sick colony in a freshwater or iodine dip (15ppt), then place the colony in a quarantine tank till it recovers before transferring to the main tank.
Do not overdose. Use the instructions on the bottle based on your tank size.
Rust brown flatworms: Brown flatworm is an acoel worm prevalent in the reefkeeping hobby. These organisms are tan-brown or rust-colored with a red dot and can reach a quarter of an inch in size. They are characterized by an oval and slightly elongated structure with two tail-like appendages at their posterior.
Rust brown flatworms grow rapidly in aquariums with high nutrient levels, often existing in high populations, they will actively attach to the Frogspawn coral’s body and block light from reaching their tissues.
Solution: These flatworms can be controlled by maintaining low nutrient levels in the reef tank through the use of carbon, aggressive protein skimming, and increased water flow. Also, proper quarantine of new corals and other fauna before placement will help to minimize the risk of transferring acoels into the tank. They can also be tackled using natural predators like the Blue Velvet Nudibranch (Chelidonura varians) and Wrasses.
In addition, an infected colony can be treated by dipping it in a dechlorinated freshwater dip for 5 to 10 seconds (Acoels are sensitive to salinity changes). Before doing that, ensure that the water has a similar pH and temperature as the aquarium water, this is to reduce the amount of stress on the colony.
Mishandling: The corals should be handled with caution during fragging, placement, relocation, or transfer between tanks; that way the risk of soft tissue damage will be highly minimized. Furthermore, shy away from fragging corals with a bone crusher of scissors to avoid splintering into the fleshy polyp area.
Solution: The use of band saw allows for a safer and precise cutting of the corals when compared to bone cutters and sheers.
Fragging and Propagation Frogspawn Corals
Frogspawn corals can reproduce through sexual and asexual means.
In the wild, they carry out sexual reproduction by releasing gametes into the water, resulting in a fertilized egg which eventually gives rise to a free-swimming planula larva. Afterward, the planula larva will metamorphose to a tiny polyp which begins to excrete calcium carbonate, thus developing into a coral.
Moreover, Frogspawn corals are capable of reproducing asexually. As seen in reef aquariums, a Frogspawn coral will bud off a small group of polyps with little skeletons present. It usually takes them a few months to turn into full-sized heads.
They will also break-off individual polyps in response to stress, these polyps will relocate elsewhere and start a new colony.
Another method is through coral fragging. However, it can be a little bit tricky because, as I have mentioned earlier, there are two types of Frogspawn corals: the wall type and the branching type.
Personally, I would not recommend fragging the wall type if you do not have the skill to make clean cuts with a bandsaw. The branching type is way more receptive to this process.
This process is simple, but you have to be cautious.
- You should ensure your hands are clean or wear a pair of gloves. Do not touch it with your bare hands. Their stings can cause skin rash for a few days!
- You will need a decent-sized, healthy, and lively coral for this purpose.
- Take out the coral and irritate it a little bit, so that it will retract the tentacles. Frogspawn corals are pretty sticky and it is easy to accidentally rip their feeder tentacle off.
- Using an electric bandsaw, divide the coral into several parts by cutting through it at least 2 inches (5 cm) away from the top.
- Attach the frag to a coral frag plug or live rock using cyanoacrylate gel or 2-part epoxy adhesive, place them back into the aquarium and provide ample water flow.
Tip: Take a frag plug and put it in the water for a couple of minutes to release the air bubbles that might be in the ceramic frag plug.
Tip #2: Treat the new frags with an iodine solution (for example, Lugol’s solution) to prevent them from contracting diseases, then you can attach them to a live rock before placing them back into the tank.
Things that you might need depending on your method:
Frogspawn Corals and Tankmates
Also, in the absence of sea anemones, Clownfish are known to host in Frogspawn corals in reef tanks. Is it good? No, it is not.
Clownfish may accidentally damage Frogspawn corals that can cause infections like brown jelly. Basically the same can be said about hermit crabs, crabs, etc.
Frogspawn corals do not like to be disturbed.
Buying Frogspawn Corals
This hardy LPS coral can be purchased at offline pet stores and from reputable online breeders/vendors as well.
Endeavor to inspect or enquire extensively to be sure of the coral’s health condition in order not to obtain specimens that may have soft tissue damage.
A head may cost about $50 – $200 depending on size and other factors.
Frogspawn corals make for a great addition to reef aquariums. It is adored for a lot of reasons which include fast growth rate, ease of care, attractive colors, and the gentle sway of its long multi-tipped tentacles in the water current.
This Euphyllia coral is lively, charming, intriguing, and beginner-friendly. Therefore, it can be easily recommended to get one or two for your reef aquarium.
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