Head and Lateral Line Erosion (HLLE)

About this condition

A chronic condition most commonly seen in surgeonfish (tangs) and angelfish, causing pitting and erosion of skin around the head and along the lateral line. It is not infectious and is primarily attributed to nutritional deficiencies and water quality issues.

Common symptoms

• Small pits and erosions along the head and lateral line
• Loss of pigmentation and whitening in affected areas
• Gradual expansion of affected skin regions
• Appearance worsens while appetite is often relatively maintained

Common causes

• Nutritional deficiencies (vitamins and minerals)
• Use of activated carbon (some evidence suggests carbon dust is a contributing factor)
• Chronic poor water quality and persistent stress
• Inadequate or improper lighting conditions

Prevention (husbandry & daily care)

Provide a varied diet including algae, frozen foods, and vitamin-supplemented preparations. Review the frequency of activated carbon filter use. Maintain stable water quality and keep fish stress to a minimum.

Related species guide

When to see a vet

What can a specialist store do?

As this is not an infectious disease, reviewing husbandry conditions takes priority over isolation. Consulting a specialist marine aquarium store with water quality data and feeding or care records can yield specific recommendations on nutrition management, lighting, and activated carbon use.

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