How Do I Know if My Coral is Healthy?

Healthy coral displays specific visual and behavioral signs that indicate it's thriving. Learning to recognize these indicators—and the warning signs of stress—helps you catch problems early.

Signs of Healthy Coral

Color and Appearance

• Vibrant coloration — Colors are rich and consistent throughout the colony
• No bleaching — White or pale patches indicate zooxanthellae loss
• Healthy tissue — Tissue covers the entire skeleton without recession

Polyp Extension

• Fully extended polyps — Polyps reach out during feeding/light periods
• Consistent behavior — Polyps retract normally when disturbed but re-extend
• Feeding response — Coral captures food particles when target fed

Growth Indicators

• New growth — White tips on SPS, new polyps on LPS/softies
• Encrusting spread — Base expands onto surrounding rock
• Colony size — Gradual increase over weeks and months

Warning Signs of Unhealthy Coral

Tissue Issues

• Bleaching — White or pale coloration (loss of zooxanthellae)
• Tissue recession — Skeleton visible at base or edges
• Brown jelly — Brown slime indicating bacterial infection
• RTN/STN — Rapid or slow tissue necrosis spreading across colony

Behavioral Changes

• Prolonged polyp retraction — Polyps stay closed for extended periods
• Excess mucus production — Stringy slime coating the coral
• No feeding response — Ignores food or fails to capture particles

Common Causes of Coral Stress

• Unstable water parameters (temperature, salinity, pH)
• Improper lighting (too much or too little PAR)
• Poor water quality (high nitrates, phosphates)
• Inadequate flow (too much or too little)
• Pests (flatworms, nudibranchs, AEFW)
• Aggression from nearby corals

Track your water parameters regularly with the ReefBay app to catch changes before they stress your coral. Stable parameters are the foundation of coral health.

When to Take Action

If you notice warning signs:

1. Test water parameters immediately
2. Check for pests with a flashlight at night
3. Verify placement (lighting, flow, aggression)
4. Consider a coral dip if pests are suspected
5. Maintain stable conditions and monitor closely

Early intervention gives coral the best chance of recovery. Browse healthy coral from verified sellers on ReefBay when you're ready to add to your collection.