Coral care guide
Blastomussa Coral Care Guide
Blastomussa corals—usually shortened to “Blastos”—combine oversized fleshy polyps with the kind of fluorescence that makes a lower-light corner look considerably more expensive. They are generally approachable LPS corals when their tissue is protected and the reef stays stable.
Soft-looking coral. Very real skeleton underneath.
Blastomussa wellsi and Blastomussa merleti
The two names most often encountered in the hobby are Blastomussa wellsi and Blastomussa merleti. Both are valid species, but retail identification should still be treated cautiously when provenance is uncertain.
B. wellsi typically develops larger, fuller polyps over a more compact colony structure. B. merleti generally has smaller polyps on distinct branching corallites. Their practical care overlaps, although the branching structure of B. merleti can make trapped debris and tissue contact easier to inspect.
Quick care guide
| Requirement | Recommended starting point |
|---|---|
| Care level | Easy to moderate |
| Lighting | Low to moderate; roughly 50–120 PAR |
| Flow | Low to moderate, indirect and varied |
| Placement | Lower to middle reef on a stable surface |
| Feeding | Optional but beneficial; small meaty foods 1–2 times weekly |
| Temperament | Usually manageable, but capable of damaging close neighbors |
| Temperature | 76–79°F |
| Salinity | 1.025–1.026 specific gravity |
| Alkalinity | Approximately 7–9 dKH, kept stable |
| Calcium | Approximately 400–450 ppm |
| Magnesium | Approximately 1,250–1,400 ppm |
| Nutrients | Detectable nitrate and phosphate without abrupt swings |
These are starting points, not guarantees. A Blasto grown under one spectrum and nutrient level may need time before it looks fully settled in another reef.
Lighting
Most Blastomussa do well under low-to-moderate light. Around 50–120 PAR is a practical starting range when the source conditions are unknown, with new arrivals beginning toward the lower end.
Increase light gradually only after the coral is inflating normally and holding stable color. Abrupt intensity changes can cause retraction, paling or bleaching. Insufficient light may contribute to darker tissue or slower growth, but nutrients, feeding and spectrum can create similar changes.
Blue-heavy lighting emphasizes fluorescence. A coral can look less electric under a whiter spectrum without being unhealthy or inaccurately represented.
Water flow
Use low-to-moderate indirect flow. The polyps should inflate without being folded sharply against the skeleton. Enough varied circulation should reach the colony to prevent mucus, food and detritus from settling between polyps or around branching corallites.
If one side remains compressed or tissue is repeatedly pushed against a skeletal edge, redirect the pump. If debris collects consistently, increase varied flow slightly rather than aiming a narrow stream at the coral.
Placement and tissue protection
The lower half of the reef is usually a sensible starting location. Mount the coral securely where snails, fish and routine maintenance cannot knock it into rockwork or another coral.
Blastomussa tissue can inflate well beyond the visible skeleton. Keep it away from sharp rock and coarse substrate that may abrade the flesh. A sandbed position can work when the colony is stable and cannot become buried, but a secure rock placement often keeps tissue cleaner and easier to inspect.
Feeding
Blastomussa are photosynthetic, but occasional direct feeding can support tissue and growth. Offer small portions of mysis, finely chopped seafood, quality frozen blends or appropriately sized LPS pellets once or twice per week.
Reduce strong circulation briefly and place food near the mouths without pressing into the tissue. Resume normal flow after the coral has had time to close around the food. Portions should be easy to swallow; rejected food can decay between polyps or raise nutrients without helping the coral.
Water chemistry and stability
Like other stony corals, Blastomussa need stable alkalinity, calcium, magnesium, temperature and salinity to maintain tissue and build skeleton. A practical foundation is alkalinity around 7–9 dKH, calcium around 400–450 ppm, magnesium around 1,250–1,400 ppm, temperature around 76–79°F and salinity around 1.025–1.026.
Keep nitrate and phosphate detectable rather than forcing the aquarium to zero. Extremely low nutrients can contribute to pale tissue and poor resilience, while chronic excess can support algae around exposed skeleton. Correct confirmed problems gradually.
Spacing and aggression
Blastomussa are often less openly aggressive than many chalices or Euphyllia, but they should not be placed in direct contact with neighbors. Inflated tissue, feeding tentacles and mesenterial filaments can extend beyond the daytime footprint, and the neighboring coral may be more aggressive than the Blasto.
Leave several inches where practical and inspect the reef after lights-out. “They looked far apart during the day” remains one of the hobby’s least useful warranties.
Acclimating a new Blasto
- Inspect the tissue, skeleton, plug and underside under white light.
- Look for fresh recession, damaged flesh, eggs, pests and nuisance algae.
- Follow a trusted coral-dip protocol and the product’s current directions.
- Begin in lower light with gentle, indirect flow.
- Keep the tissue clear of sharp rock, sand and aggressive neighbors.
- Allow the coral to settle before feeding heavily or moving it repeatedly.
A recently shipped colony may remain partially retracted for a short period. Look for steady improvement, intact tissue and an increasingly reliable feeding response.
Reading the coral
Healthy signs
- Full polyps with tissue extending safely beyond the skeleton
- Regular inflation and a clear feeding response
- Stable color under consistent lighting
- Clean tissue edges without fresh exposed skeleton
- New polyps or skeletal growth around the colony edge
Warning signs
- Tissue remaining tightly retracted against the skeleton
- Fresh white skeleton or a widening recession line
- Persistent gaping mouths
- Brown gelatinous material or rapid tissue loss
- Repeated damage on the side facing a pump, rock or neighboring coral
- Algae establishing on newly exposed skeleton
Troubleshooting
| Symptom | Check first | Practical response |
|---|---|---|
| Stays deflated | Direct flow, handling, salinity or alkalinity instability | Reduce confirmed stress and stop repeated relocation |
| Pale or bleaching | Recent light increase, temperature, very low nutrients | Reduce abrupt stress and acclimate gradually |
| Tissue recession | Injury, aggression, instability, pests or infection | Inspect closely, isolate the cause and protect healthy tissue |
| Damage on one side | Pump direction, rock contact, neighboring coral | Redirect flow or create more space |
| Algae on skeleton | Previous tissue loss plus available light and nutrients | Address the cause of recession and keep the area clean carefully |
| Refuses food | Stress, excessive flow, oversized food | Try a smaller portion after lights dim and reduce flow briefly |
Rapid tissue loss or brown gelatinous material requires prompt attention. Isolate the coral when practical, avoid sharing contaminated tools or water, and verify critical parameters immediately.
Final take
Start Blastomussa in modest light with indirect flow, protect the inflated tissue, keep water chemistry stable and feed small portions when useful. Give the colony enough space and time to settle before deciding it needs another change.