Common Diseases in Corals, Bleaching Causes, and Prevention Methods
Explanation of common diseases and troubles in corals, including bleaching, RTN, and brown jelly, covering symptoms, causes, and remedies. Protect your precious corals through water quality management and early detection.
Key Takeaways
Explanation of common diseases and troubles in corals, including bleaching, RTN, and brown jelly, covering symptoms, causes, and remedies. Protect your precious corals through water quality management and early detection.
Corals are exceptionally delicate organisms in marine aquariums and react sensitively to even minor fluctuations in water temperature, water quality, and light intensity. To maintain beautiful polyps over the long term, careful observation to catch early warning signs of disease or problems, combined with preventive management, is essential. This article provides detailed explanations of common coral diseases, their causes and treatments, and tips for introducing healthy specimens.
Main Causes of Coral Disease
Coral problems fall into two broad categories: "environmental stress" and "infection by pathogenic organisms."
The primary form of environmental stress is sudden changes in water temperature and quality. Corals harbor symbiotic zooxanthellae (zooxanthellae algae) within their tissues and obtain energy through photosynthesis. When water temperature exceeds 28°C or major parameters—alkalinity (ALK), calcium (Ca), and magnesium (Mg)—become severely imbalanced, the zooxanthellae abandon the coral. This is the direct mechanism behind bleaching.
Infection by pathogenic organisms involves bacteria, parasites, protozoa, and other agents. Introducing newly purchased specimens or live rock into the main tank without quarantine significantly increases the risk of harboring invisible pathogens. Even apparently healthy individuals may suddenly show symptoms when stress from environmental changes builds up. It is not uncommon for disease to surface all at once under such conditions.
Common Diseases, Troubles, and Remedies
Bleaching
Bleaching is the most commonly observed problem in coral keeping. The coral loses its color, turning beige or white, and the skeleton becomes visible underneath. In mild cases, restoring water temperature to 25–26°C and increasing water change frequency can allow the zooxanthellae to recover naturally. However, if bleaching persists for more than two weeks, the coral's stamina declines drastically, often leading to death; early intervention is critical.
- Main causes: Water temperature rise (exceeding 28°C), excessively strong lighting, sudden changes in pH or ALK
- Remedies: Stabilize water temperature (25–26°C), increase water change volume to 1.5–2× normal levels, review lighting duration