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Royal grammas are one of the hardier marine fish and are less disease-prone than species like the blue tang. That said, they are not immune to marine ich, velvet, flukes, and bacterial infections. Most royal gramma health problems are preventable with proper quarantine, stable water quality, and appropriate tankmates. This guide covers the most common royal gramma diseases, how to identify them, and what to do.
Marine Ich (Cryptocaryon irritans)
Marine ich is the most common disease in saltwater fish and royal grammas can contract it, though they are significantly less susceptible than blue tangs. Royal grammas may show symptoms during a tank-wide ich outbreak even if they were not the first fish affected.
Symptoms: Small white spots on the body and fins resembling grains of salt; flashing (rubbing against rockwork); rapid breathing; appetite loss; lethargy.
Cause: Ciliate parasite Cryptocaryon irritans, introduced through new fish or live rock without quarantine.
Treatment: Marine ich cannot be reliably treated in a display reef tank. Move affected fish to a hospital tank and treat with copper-based medication at therapeutic levels for a minimum of 30 days, or use hyposalinity (1.009-1.010 specific gravity) for 4-6 weeks. Leave the display tank fallow (fish-free) for a minimum of 72 days to break the parasite life cycle.
Prevention: Quarantine all new fish for 4-6 weeks. Maintain stable water parameters and minimize stress.
Velvet (Amyloodinium ocellatum)
Marine velvet is more dangerous than ich and progresses rapidly. Royal grammas are susceptible and may show symptoms quickly once exposed.
Symptoms: Fine gold, rust, or yellow dust-like coating on the body and fins, most visible under a flashlight at an angle; rapid breathing; flashing; lethargy; appetite loss. Gill involvement often precedes visible body symptoms.
Treatment: Move all fish to a hospital tank immediately. Treat with copper-based medication or chloroquine phosphate. Leave the display tank fallow for 72 days. Do not delay - velvet progresses faster than ich and is rapidly fatal.
Prevention: Quarantine all new additions. Velvet can survive on live rock and corals.
Flukes (Monogenean Trematodes)
Flukes are external parasites that attach to the skin and gills. Gill flukes can cause significant damage before visible symptoms appear.
Symptoms: Rapid breathing; flashing; excess mucus production; scratching against rockwork. Gill flukes may cause rapid breathing and lethargy without other obvious symptoms.
Treatment: Praziquantel is the most effective treatment and is reef safe at appropriate doses. Treat in a hospital tank. Praziquantel treatment during quarantine is good practice for all new marine fish.
Prevention: Quarantine all new fish for 4-6 weeks.
Bacterial Infections
Bacterial infections in royal grammas are usually secondary - developing at sites of injury from aggression, or in fish weakened by poor water quality or chronic stress.
Symptoms: Red or inflamed patches; fin deterioration; open sores or ulcers; lethargy; appetite loss.
Cause: Often follows physical injury from tankmate aggression or damage from parasites. Poor water quality is a contributing factor.
Treatment: Improve water quality immediately. Treat with a broad-spectrum antibacterial medication in a hospital tank. Identify and address the underlying cause - if aggression is the source, separate the fish.
Aggression Injuries
While not a disease, physical injuries from aggression are a common health problem in royal grammas. Two royal grammas in a tank without adequate territory will fight, often resulting in torn fins, wounds, and secondary bacterial infection. A royal gramma housed with an aggressive dottyback or damselfish may also sustain injuries.
Prevention: Keep only one royal gramma per tank. Avoid housing with known aggressive species. See our Royal Gramma Tankmates guide.
Prevention: The Most Important Section
- Quarantine all new fish for 4-6 weeks - the single most effective prevention measure
- Maintain stable water quality - ammonia and nitrite at 0 ppm, nitrate below 20 ppm. See our Best Reef Test Kits guide
- Use an auto top-off system to prevent salinity instability - see our Best Auto Top-Off Systems guide
- Keep only one royal gramma per tank to prevent aggression injuries
- Have a hospital tank ready before purchasing any marine fish
- Provide adequate rockwork so the fish can establish territory and reduce stress