Why does my Hammer Coral (Fimbriaphyllia parancora) inflate and deflate throughout the day, and when should I worry?

Normal cycles include daytime expansion for light capture and slight night contraction. Concern arises if tissue stays retracted for days, exposing sharp septa, or shows localized gel-like decay (brown jelly). Check for excessive flow, abrupt PAR changes, alk swings, or nudibranchs. Stabilize dKH 8–9, Ca 420–450, Mg ~1300, keep phosphate detectable, and perform an iodine dip if tissue loss starts.

What lighting keeps color without risking bleaching or dulling?

Branching hammers favor moderate PAR (80–150). Too high washes color and shortens polyp; too low produces brown, elongated tentacles. Ramp intensity slowly over 2–3 weeks. Blue-heavy spectra (400–470 nm) help greens and golds pop, but provide some white for growth. If tips pale while bases darken, reduce PAR or increase diffusion and improve nutrients slightly.

My hammer stings neighbors inconsistently. What affects sweeper length and aggression?

Nighttime sweepers extend 2–6 inches, longer with higher flow, intermittent feeding, and when sensing rival cnidarians (especially torches). Chemical cues from other LPS can trigger extra extension. Give 6–8 inches of space and avoid down-current placement near meaty LPS. Activated carbon and regular water changes can reduce chemical warfare, but physical distance is still the best control.

How can I prevent and respond to brown jelly in a branching hammer colony?

Prevention: maintain stable parameters, moderate flow, gentle handling, and quarantine new Euphylliids. At first sign (brown, stringy mucus, rapid tissue melt), immediately siphon the jelly, remove the affected head by cutting the branch below healthy tissue, and perform an iodine dip. Increase aeration and flow, run fresh carbon, and reduce organics. Disinfect tools to avoid cross-contamination.

Neon Hammer Coral

Euphyllia Hammers

Overview

Hammer Coral has thick, fleshy polyps with hammer- or anchor-shaped tips that extend from branching heads. Fimbriaphyllia parancora is a branching large-polyp stony coral that prefers moderate light and gentle to moderate, indirect flow. It relies on symbiotic algae but will accept small meaty foods; occasional feeding can boost growth and maintain color. Allow several inches of space for its sweeper tentacles and avoid strong flow or close placement to other corals.

Quick Facts

Care Moderate

Lighting Moderate

Flow Moderate, indirect

Placement Mid–Low

Temperament Semi-aggressive (long sweeper tentacles; 6+ inches spacing)

Recommended Parameters

Temp 76–82°F

pH 8.1–8.4

Salinity 1.025–1.026

Calcium 400–450 ppm

AlkAlkalinity 8–9 dKH

Magnesium 1280–1350 ppm

Feeding photosynthetic, mysis shrimp, enriched brine shrimp, finely chopped shrimp/clam, zooplankton, microplankton, marine snow, powdered coral foods

Care & Placement

Hammer Coral (Fimbriaphyllia parancora) thrives with stable, moderate conditions. Provide medium light (PAR ~80–150); start lower and increase over 2–3 weeks to avoid bleaching. Aim for moderate, indirect water flow that gently moves tentacles without whipping; too much flow tears tissue, too little invites detritus and film algae. Target-feed 1–2 times weekly with small meaty foods (mysis, chopped shrimp) or fine coral foods; feed after lights dim when tentacles are extended. Keep temperature 76–79°F, salinity 1.025–1.026 (35 ppt), pH 8.1–8.4, alkalinity 8.0–9.5 dKH, calcium 400–450 ppm, magnesium 1250–1350 ppm, nitrate 2–15 ppm, phosphate 0.03–0.08 ppm. Test weekly with reliable kits and a refractometer; this coral is sensitive to rapid alkalinity and salinity swings and to copper.Place low to mid in the tank on stable rock or sand-supported rubble; avoid sharp edges contacting the skeleton. Leave 6–8 inches clearance from neighbors—sweeper tentacles extend at night and can sting other corals. Generally peaceful toward its own genus but may fight with different morphs. Acclimate by dripping 30–60 minutes and use light-screening or reduced intensity for a week. Signs of stress include fading (too much light), retracted polyps or receding tissue (alk swings, pests, or infection). If brown jelly appears, siphon, iodine dip, increase flow, and remove affected heads. Keep fish that won’t nip; clownfish may interact, so watch for irritation. Regularly baste to lift detritus and maintain stable parameters for steady growth.

FAQ

Frequently Asked Questions

About the Neon Hammer Coral

Why does my Hammer Coral (Fimbriaphyllia parancora) inflate and deflate throughout the day, and when should I worry?

Normal cycles include daytime expansion for light capture and slight night contraction. Concern arises if tissue stays retracted for days, exposing sharp septa, or shows localized gel-like decay (brown jelly). Check for excessive flow, abrupt PAR changes, alk swings, or nudibranchs. Stabilize dKH 8–9, Ca 420–450, Mg ~1300, keep phosphate detectable, and perform an iodine dip if tissue loss starts.
What lighting keeps color without risking bleaching or dulling?

Branching hammers favor moderate PAR (80–150). Too high washes color and shortens polyp; too low produces brown, elongated tentacles. Ramp intensity slowly over 2–3 weeks. Blue-heavy spectra (400–470 nm) help greens and golds pop, but provide some white for growth. If tips pale while bases darken, reduce PAR or increase diffusion and improve nutrients slightly.
My hammer stings neighbors inconsistently. What affects sweeper length and aggression?

Nighttime sweepers extend 2–6 inches, longer with higher flow, intermittent feeding, and when sensing rival cnidarians (especially torches). Chemical cues from other LPS can trigger extra extension. Give 6–8 inches of space and avoid down-current placement near meaty LPS. Activated carbon and regular water changes can reduce chemical warfare, but physical distance is still the best control.
How can I prevent and respond to brown jelly in a branching hammer colony?

Prevention: maintain stable parameters, moderate flow, gentle handling, and quarantine new Euphylliids. At first sign (brown, stringy mucus, rapid tissue melt), immediately siphon the jelly, remove the affected head by cutting the branch below healthy tissue, and perform an iodine dip. Increase aeration and flow, run fresh carbon, and reduce organics. Disinfect tools to avoid cross-contamination.