Why does my “Blueberry Duncan” look plain green or brown in daylight?

The blue/purple look is mostly fluorescence under strong blue/actinic channels. Under whiter spectra, zooxanthellae pigment and tissue color dominate, so it appears greener or browner. Increase blue/violet channels for pop, but keep PAR moderate (80–150). If it’s dull even under blues, check nutrients (NO3 5–15 ppm, PO4 0.03–0.1) and avoid over-filtration that strips color. Don’t chase color by blasting light.

My Duncan stays retracted for days—what hidden issues should I check?

Beyond parameters, look for irritants: vermetid snails (mucus webs), bristleworms picking at food, amphipod swarms, or a gall crab in the skeleton. Also check for direct, laminar flow hitting the oral disc and micro-shading from overgrown frags nearby. Glue over vermetid tubes, adjust to indirect, pulsing flow, and baste detritus from the base. A brief iodine dip helps after physical irritation.

How do I push multi-head growth without stressing the colony?

Stability grows heads. Keep alkalinity 8–9 dKH, calcium 420–450 ppm, magnesium ~1350. Feed small, frequent portions (mysis, enriched brine, pellet) 2–3 times weekly; oversize prey slows recovery. Aim for moderate PAR and low-moderate, chaotic flow. Avoid rapid nutrient swings; zeros stall growth. Once branching is visible, frag between heads at the skeleton, not through tissue, and do an iodine dip.

The base is receding while tops look fine—what causes “bottom-up” loss?

Shaded skirts plus trapped detritus invite bacteria and sponges. Increase crossflow around the base, raise the colony slightly, and turkey-baste weekly. Keep NO3/PO4 non-zero to support tissue. If you see brown jelly (stringy, foul tissue), immediately siphon, iodine dip, and cut away healthy heads above the rot. Monitor alk stability—daily swings often show first at the base.

TSA Blueberry Duncan Coral

Beginner Corals LPS Duncan

Overview

Blueberry Duncan Coral has fleshy, round polyps with short, ringed tentacles and a green to blue center. Duncanopsammia axifuga is a branching large-polyp stony coral; it prefers low to moderate light and gentle to moderate water flow. It hosts symbiotic algae for energy and readily accepts small meaty foods, with regular feeding promoting faster growth and fuller polyp extension. Place it on stable rockwork or sand with some space from aggressive neighbors, and avoid strong, direct flow that keeps the polyps from opening.

Quick Facts

Care Easy

Lighting Low–Moderate

Flow Moderate, indirect

Placement Low–Mid

Temperament Peaceful to semi-aggressive (3–4 inches spacing)

Recommended Parameters

Temp 76–80°F

pH 8.1–8.4

Salinity 1.025–1.026

Calcium 400–450 ppm

AlkAlkalinity 8–10 dKH

Magnesium 1250–1350 ppm

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

Care & Placement

Blueberry Duncan Coral (Duncanopsammia axifuga) thrives with stable, moderate conditions and regular feeding. Provide moderate light (PAR ~80–150) and indirect, moderate flow that keeps detritus off the skeleton without blasting the polyps; too much flow leads to closed heads and tissue wear. Target-feed 2–3 times weekly with small meaty foods (mysis, chopped krill, reef roids) to support growth and new heads. Keep temperature 75–79°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 2–10 ppm, phosphate 0.02–0.08 ppm, and zero ammonia/nitrite. Test weekly, verify salinity with a calibrated refractometer, and avoid rapid swings—this coral is sensitive to sudden changes in alkalinity and light.Place low to mid in the tank on stable rock or the sandbed with the plug secured, giving 3–4 inches clearance from aggressive neighbors; Duncan sweepers are short and mild, but they can be stung by torches, hammers, and galaxea. Light acclimate by starting in lower light and moving up over 1–2 weeks; drip acclimate 30–45 minutes and consider a coral dip to exclude pests. Signs of trouble include bleaching from abrupt light increases, polyp recession from alk swings, and brown jelly after damage—improve flow, siphon infected tissue, and consider an iodine dip if needed. Watch for nipping fish (angels, butterflies) and keep nutrients non-zero to avoid starvation and sulking.

FAQ

Frequently Asked Questions

About the TSA Blueberry Duncan Coral

Why does my “Blueberry Duncan” look plain green or brown in daylight?

The blue/purple look is mostly fluorescence under strong blue/actinic channels. Under whiter spectra, zooxanthellae pigment and tissue color dominate, so it appears greener or browner. Increase blue/violet channels for pop, but keep PAR moderate (80–150). If it’s dull even under blues, check nutrients (NO3 5–15 ppm, PO4 0.03–0.1) and avoid over-filtration that strips color. Don’t chase color by blasting light.
My Duncan stays retracted for days—what hidden issues should I check?

Beyond parameters, look for irritants: vermetid snails (mucus webs), bristleworms picking at food, amphipod swarms, or a gall crab in the skeleton. Also check for direct, laminar flow hitting the oral disc and micro-shading from overgrown frags nearby. Glue over vermetid tubes, adjust to indirect, pulsing flow, and baste detritus from the base. A brief iodine dip helps after physical irritation.
How do I push multi-head growth without stressing the colony?

Stability grows heads. Keep alkalinity 8–9 dKH, calcium 420–450 ppm, magnesium ~1350. Feed small, frequent portions (mysis, enriched brine, pellet) 2–3 times weekly; oversize prey slows recovery. Aim for moderate PAR and low-moderate, chaotic flow. Avoid rapid nutrient swings; zeros stall growth. Once branching is visible, frag between heads at the skeleton, not through tissue, and do an iodine dip.
The base is receding while tops look fine—what causes “bottom-up” loss?

Shaded skirts plus trapped detritus invite bacteria and sponges. Increase crossflow around the base, raise the colony slightly, and turkey-baste weekly. Keep NO3/PO4 non-zero to support tissue. If you see brown jelly (stringy, foul tissue), immediately siphon, iodine dip, and cut away healthy heads above the rot. Monitor alk stability—daily swings often show first at the base.

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