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HomeProblemsRapid Tissue Necrosis (RTN)

algae

Rapid Tissue Necrosis (RTN)

Fast-progressing coral tissue death, typically SPS

Symptoms

Coral tissue sloughs off rapidly — often within hours — leaving bare white skeleton.
Usually starts at the base or branch tips of SPS corals (E1: typically SPS).
Mucus may be visible at the boundary between living tissue and bare skeleton.

Common Causes

Stress response to sudden parameter swings (temperature, salinity, alkalinity).
Freshly fragged, shipped, or handled corals are most vulnerable.
Bacterial involvement is suspected but not confirmed in all cases.

What to Check

Test temperature, salinity, and alkalinity immediately — correct any spike gently.
Identify how far the tissue loss has progressed — cut back to healthy tissue if acting fast.
Review recent changes: new livestock, equipment changes, or dosing adjustments.

What Not to Do

Do not make large simultaneous parameter changes — this often accelerates tissue loss.
Do not treat the whole tank without diagnosis — supportive stability first.

This guide is informational and does not replace professional veterinary advice. If fish are severely ill, consult a veterinarian.