Why does my Doomsday Pectinia show big nighttime tentacles but stay retracted by day?

Pectinia alcicornis is strongly nocturnal. It inflates tissue and extends long capture tentacles after lights out for plankton and small meaty prey. Support this rhythm with moderate, random flow at night and low–moderate PAR (80–150) by day. If daytime retraction worsens, check for fish nipping, excess light, or alkalinity swings. Feed small particle foods 1–2 hours after lights out to boost growth.

The valleys are receding while the rims look okay—what’s causing this pattern?

Valley recession often points to detritus buildup and shadowing, compounded by unstable alkalinity. Increase cross-flow to keep valleys clean, tilt the colony slightly vertical, and provide diffuse light rather than point-source hotspots. Keep alk stable around 8–9 dKH. If tissue looks slimy or smells foul, suspect bacterial issues; perform an iodine or broad-spectrum coral dip and improve water clarity with fresh carbon.

What placement maximizes color without bleaching this morph?

Start low and shaded, then acclimate to 80–150 PAR using mesh or gradual intensity ramps over 2–3 weeks. This species colors best under diffuse lighting (T5 hybrids or high-mount LEDs with wide spread). Excess light washes fluorescent pigments; too little flattens contrast. Maintain nutrients in the “not zero” range (NO3 5–15 ppm, PO4 0.03–0.1). A sloped or vertical mount prevents sediment in folds and improves polyp health.

How aggressive is it, and how much room should I give?

Expect long nighttime sweepers, often 4–6 inches, occasionally more on hungry or stressed colonies. Maintain a generous buffer from other LPS and chalices. Avoid direct conflicts with fleshy neighbors; Pectinia stings are potent and can cause melting. Run fresh activated carbon and ensure good gas exchange to reduce allelopathy. If it’s consistently launching long sweepers, increase feeding and review PAR to reduce resource stress.

TSA Black Lotus Pectinia Coral

Chalice Pectinia LPS

Overview

Doomsday Pectinia Coral shows antler-like ridges and ruffled plates, with sweeper tentacles extending at night. Pectinia alcicornis is a stony, plating/branching LPS coral that does well under moderate light and moderate, variable flow. It is photosynthetic with symbiotic algae but benefits from occasional small meaty feedings, supporting growth and color. Place with ample space, as long sweeper tentacles can sting nearby corals, and avoid strong light when newly introduced.

Quick Facts

Care Moderate

Lighting Low–Moderate

Flow Moderate, indirect

Placement Low–Mid

Temperament Aggressive (8–10 inches spacing)

Recommended Parameters

Temp 76–80°F

pH 8.1–8.4

Salinity 1.025–1.026

Calcium 420–450 ppm

AlkAlkalinity 8–10 dKH

Magnesium 1280–1350 ppm

Feeding photosynthetic, mysis shrimp, enriched brine shrimp, copepods, zooplankton, microplankton, finely chopped marine meats, coral-specific powdered foods

Care & Placement

Doomsday Pectinia Coral (Pectinia alcicornis) thrives with stable, moderate conditions and careful spacing. Provide moderate light (PAR 80–150), acclimating slowly from lower light to avoid bleaching; a PAR meter or gradual screen method helps. Use moderate, indirect flow that keeps detritus from settling in its valleys without whipping tissue; aim for a gentle, random pattern. Feed 2–3 times weekly after lights dim with small meaty foods (mysis, chopped krill, reef roids) when feeder tentacles extend; this supports growth and coloration. Keep temperature 75–78°F (24–26°C), salinity 1.025–1.026, pH 8.1–8.4, alkalinity 8–9.5 dKH, calcium 400–450 ppm, magnesium 1250–1350 ppm, nitrate 2–15 ppm, phosphate 0.03–0.10 ppm. Avoid rapid swings—this coral is sensitive to sudden changes, especially alkalinity and light.Place mid to lower in the tank on stable rock, not in sand, with 6–10 inches of space from neighbors; Pectinia has long, stinging sweeper tentacles and is aggressive. Compatible with peaceful LPS and soft corals at a distance; keep away from delicate SPS. Acclimate with a drip over 30–45 minutes and light-acclimate over 1–2 weeks. Watch for tissue recession from detritus buildup or abrasive flow, and for brown jelly after damage; siphon promptly, iodine dip if needed, and frag past dead tissue. If color pales, reduce light and feed more; if tissue darkens and grows algae, increase flow and check nutrients. Keep hands and tools gentle—sharp skeleton can tear tissue.

FAQ

Frequently Asked Questions

About the TSA Black Lotus Pectinia Coral

Why does my Doomsday Pectinia show big nighttime tentacles but stay retracted by day?

Pectinia alcicornis is strongly nocturnal. It inflates tissue and extends long capture tentacles after lights out for plankton and small meaty prey. Support this rhythm with moderate, random flow at night and low–moderate PAR (80–150) by day. If daytime retraction worsens, check for fish nipping, excess light, or alkalinity swings. Feed small particle foods 1–2 hours after lights out to boost growth.
The valleys are receding while the rims look okay—what’s causing this pattern?

Valley recession often points to detritus buildup and shadowing, compounded by unstable alkalinity. Increase cross-flow to keep valleys clean, tilt the colony slightly vertical, and provide diffuse light rather than point-source hotspots. Keep alk stable around 8–9 dKH. If tissue looks slimy or smells foul, suspect bacterial issues; perform an iodine or broad-spectrum coral dip and improve water clarity with fresh carbon.
What placement maximizes color without bleaching this morph?

Start low and shaded, then acclimate to 80–150 PAR using mesh or gradual intensity ramps over 2–3 weeks. This species colors best under diffuse lighting (T5 hybrids or high-mount LEDs with wide spread). Excess light washes fluorescent pigments; too little flattens contrast. Maintain nutrients in the “not zero” range (NO3 5–15 ppm, PO4 0.03–0.1). A sloped or vertical mount prevents sediment in folds and improves polyp health.
How aggressive is it, and how much room should I give?

Expect long nighttime sweepers, often 4–6 inches, occasionally more on hungry or stressed colonies. Maintain a generous buffer from other LPS and chalices. Avoid direct conflicts with fleshy neighbors; Pectinia stings are potent and can cause melting. Run fresh activated carbon and ensure good gas exchange to reduce allelopathy. If it’s consistently launching long sweepers, increase feeding and review PAR to reduce resource stress.