Care guide · Marine · corals

Torch coral

Euphyllia glabrescens

Species level

Photo: Josuevg · Source · CC BY-SA 3.0Resized and compressed; no cropping or colour changes.

Euphyllia glabrescens is a stony coral whose long tentacles move conspicuously with the water. Their ends usually have distinct, rounded tips. This appearance makes torch coral attractive, but the extended polyps also determine how much open space it needs. It is not an animal to squeeze into the last gap between established colonies. Choose it for a mature reef with stable conditions and a dedicated position in indirect flow. The trade name of an expensive colour variant does not establish different care requirements. This guide covers the named species, distinguishing its lighting needs, vulnerable tissue and capacity to injure neighbouring corals. A healthy colony particularly needs space, stability and attention to changes.

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At a glance

Identification level: Species level
Coral group: LPS
Difficulty: Moderate
Growth and pruning: Moderate
Temperature: 24–26 °C
Specific gravity (SG at 25 °C): 1.025–1.026 SG
pH: 8.1–8.3
Alkalinity: 8–9 °dKH
Calcium: 400–450 mg/L
Magnesium: 1250–1350 mg/L
Light requirement: Moderate
Flow requirement: Moderate
Position: Low, Middle
Aggression: Aggressive
Supplementary feeding: Optional

Water values are reef-care guidance, not proven species limits. PAR describes only the stated culture experience; stability and gradual acclimation remain important.

About this coral

A branching calcareous skeleton supports the moving tentacles. Living tissue extends around the upper rim of each skeletal head; handle the coral by a bare base or holder. A fully retracted colony looks quite different from its daytime appearance. Hammer corals have differently shaped tentacle tips and belong to Fimbriaphyllia in the current classification. Relatedness does not make direct contact safe. Colour and fluorescence also change with lighting and photography; assess tissue condition and identification when buying.

Natural habitat

This species occurs in the Indo-Pacific. Sheltered reef conditions and water that is not permanently crystal clear form part of its natural context. This does not mean polluted aquarium water is desirable. In a tank, the same animal at the same height can receive very different light because of optics, clarity and reflection. Translate its environment into indirectly moving water and space around the colony, rather than an untested recipe based on collection depth. Ask about the parent colony's conditions when purchasing a cultured frag.

Aquarium and layout

Reserve a stable rock position with clearance in the direction in which flow carries the tentacles. A tipping plug can press living tissue against rock. Keep sand off the heads and leave the coral accessible for inspection. The eventual colony requires substantially more space than a small frag. No species-specific minimum volume has been established that guarantees safety independently of colony size and layout. In a small aquarium, also allow for fewer alternative positions and faster fluctuations.

Water conditions

Stable salinity and temperature matter more than rapidly chasing different targets. Skeletal growth consumes calcium and alkalinity; supplementation follows measured consumption by the whole aquarium. Check an unexpected result before dosing and record maintenance that might explain it. Nitrate and phosphate are not simple dirt indicators that must always read zero. Where species-specific evidence is inadequate, we do not display a hard nutrient limit. Persistent closure calls for examining several factors, not automatically making a chemical correction.

Lighting and acclimation

Moderate lighting is a useful starting point. The consulted advice does not establish sufficiently consistent species-specific PAR limits to publish one guaranteed range. A light can appear powerful enough while still producing shaded areas or local peaks. Measure where the polyps actually sit. Acclimate a new animal gradually, without imposing a fixed increase schedule on every aquarium. A temporarily lower or dimmer position can help, but should not become a permanently dark location. Fading or reduced expansion calls for investigation and does not by itself diagnose a lighting problem.

Water movement

Provide movement that lets the tentacles sway without repeatedly striking their own skeleton. Sources describe anything from moderate to stronger flow; the shared practical point is that a hard, continuous pump jet onto the tissue is unsuitable. Change direction or pattern if necessary before simply adding power. Observe the colony under different pump settings and as neighbours grow. A bare patch on the continuously exposed side may indicate mechanical damage.

Feeding

Symbiotic microalgae make an important nutritional contribution. Small animal-based particles may be offered as a supplement when the polyps actually ingest them. Do not push a large piece into the mouth. Start modestly and stop when food is released or remains uneaten. Target feeding is an option here, not a reason to add ever more coral powder every day. Watch for fish or shrimp pulling food away. Every additional feed contributes to the load on the aquarium.

Growth and behaviour

A healthy branching colony can develop new heads. The space it occupies increases beyond the skeleton itself: fully expanded tentacles enlarge the area that must remain clear. Follow growth with photographs from the same angle and check the boundary towards neighbours. A new head is different from an entire polyp detaching. Polyp bailout can be a serious stress response and should not be treated as desirable propagation. Sudden tissue loss requires prompt assessment of the system.

Aggression and spacing

Torch coral can damage neighbours through stinging contact. Observe tentacle extension outside normal viewing times too, including the effect of flow direction. A measured gap is only a snapshot: growth or a different pump setting can change the situation. There is therefore no universal safe distance in centimetres. Plan a dedicated zone that keeps living neighbours out of reach. If a neighbour deteriorates on the side facing the torch, investigate contact promptly and separate the animals if necessary without causing further tissue damage.

Keeping with fish

Fish that nip fleshy coral polyps need particular attention. A dwarf angelfish can present a real risk even when its general reef label merely carries a caution. Clownfish may use a coral as a host; this is neither necessary nor invariably harmless. Repeated rubbing in a small colony can interfere with expansion. Observe actual behaviour rather than relying on photographs of apparently successful combinations. A sand-sifting fish may also bury a low-placed colony without eating coral.

Keeping with corals

A hammer coral is not a safe touching neighbour simply because it looks related. Give Duncan coral and other fleshy LPS their own space too. SPS can occupy different light and flow zones, but should not intersect tentacle reach or future growth space. Fast-growing soft corals can shade neighbours; chemical competition also deserves attention in a mixed reef. A conditional relationship means coexistence in an appropriately arranged system, not sharing one small rock.

Other invertebrates

Coral safety varies greatly among marine invertebrates. A grazing snail may mainly threaten an unsecured frag by knocking it over, whereas an opportunistic crab may approach tissue or captured food. Shrimp that actively steal food can repeatedly disturb a weak polyp. Assess the exact species and what it does. Starfish and sea urchins cannot each be given a blanket safe rating. Freshwater animals from the existing database do not belong in this marine combination.

Propagation and fragging

A healthy, widely branching colony offers different possibilities from a compact colony with continuous living tissue. If necessary, ask an experienced grower to take a frag through a suitable skeletal section. Cutting an inflated polyp or pulling its tissue causes unnecessary damage. Use eye and hand protection against mucus and sharp skeletal parts. Glue only a holder or suitable dead skeleton. A recently transported or deteriorating colony is not a suitable starting point for propagation.

Possible problems

Watch for persistently retracted polyps, receding tissue, tissue detachment and changes spreading rapidly to other heads. Brown mucus can accompany serious deterioration but does not establish a specific pathogen without investigation. Check water conditions, pump exposure, contact damage and nipping. Do not apply an arbitrary mixture of treatments to the reef. Document the progression and seek experienced help for rapid tissue loss; isolation may limit further spread when achievable without additional injury. A brief response to touch differs from sustained deterioration.

Keeping with other species

Care products

No sufficiently supported match to a specific existing care product has been established for this coral. Follow the feeding and care chapters; an absent product card does not mean feeding or measurements are unnecessary.

Sources & review

This care guide draws on several specialist sources and was last checked on 9 October 2026.

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