What Causes Brown Jelly Disease in Corals and How Do I Stop It?
Quick Answer
Brown jelly disease is a fast-moving bacterial infection that appears as brown mucus on coral tissue. Remove affected coral immediately, frag away healthy sections, and dip in coral disinfectant.
Brown jelly disease (BJD) is a devastating bacterial infection that can kill corals within hours. The "brown jelly" is actually decomposing coral tissue mixed with bacteria, typically Vibrio species. Once started, it spreads rapidly across the coral and can infect neighboring colonies.
Identifying Brown Jelly Disease
BJD appears as:
- Brown, stringy mucus on coral tissue
- Tissue sloughing off to expose skeleton
- Foul smell in severe cases
- Rapid spread (can consume a colony in 24-48 hours)
It most commonly affects LPS corals like torches, hammers, frogspawn, and elegance corals, but can attack any stressed coral.
What Causes Brown Jelly
BJD is opportunistic—bacteria attack weakened corals. Common triggers include:
- Physical damage – Tissue tears, shipping stress, fragging wounds
- Sting damage – From aggressive neighboring corals
- Poor water quality – Elevated ammonia, nitrite, or sudden parameter swings
- Temperature stress – Rapid heating or cooling
- Low flow – Dead spots where bacteria thrive
Emergency Treatment Steps
- Remove the coral immediately – Don't wait. BJD spreads fast and can infect nearby corals.
- Cut away healthy tissue – Frag any unaffected parts at least 1 inch away from the brown jelly. Work quickly.
- Dip healthy frags – Use Lugol's iodine dip or commercial coral dip for 5-10 minutes.
- Discard infected portions – Don't try to save heavily infected sections—they're gone.
- Quarantine survivors – Keep saved frags in a separate container to monitor before returning to display.
Prevention
To prevent BJD:
- Quarantine and dip all new corals before adding to your tank
- Maintain stable water parameters (track with the ReefBay app)
- Ensure adequate flow around euphyllia corals
- Space corals properly to avoid sting wars
- Act immediately if you see any tissue damage or recession
Brown jelly is one of the scariest things reef keepers encounter, but quick action can save healthy portions of affected colonies and protect your other corals.
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