nutritional · both tank

HLLE (Head and Lateral Line Erosion)

HLLE (Head and Lateral Line Erosion, also Hole-In-The-Head) is the progressive erosion of pits or holes along the lateral line and head. Caused by nutritional deficiency, activated carbon overuse, or stray voltage.

Reviewed by the Fast Aquatics husbandry team · Updated May 2026
Severity: Mild but disfiguring; reversible if caught early

Symptoms to look for

What causes it

Vitamin deficiency (especially A, D, C), low-quality dry food, excessive activated carbon, stray voltage from equipment.

Treatment options

Multiple effective treatments exist. Pick based on your tank type, livestock sensitivity, and severity. Always treat in a separate quarantine/hospital tank - most medications are toxic to coral, invertebrates, and live rock biology.

Diet upgrade. Switch to high-quality varied diet: frozen mysis, brine shrimp, nori, Selcon vitamin soak. Add fresh garlic juice to food. Most cases improve within 4-8 weeks of diet change.
Remove activated carbon. Carbon may strip trace nutrients. Test removing it for 4 weeks while feeding a vitamin-rich diet.
Check for stray voltage. Use a multimeter probe in the tank with one end grounded. Reading should be near 0 mV. Replace any equipment showing voltage leak.

Prevention

Feed varied, high-quality diet from day one. Soak dry food in Selcon or VitaChem twice a week. Don't over-rely on activated carbon.

Frequently asked questions

What does HLLE (Head and Lateral Line Erosion) look like?

Small pits or holes along the lateral line. Erosion around the eyes and head. Color loss in affected areas.

What causes HLLE (Head and Lateral Line Erosion)?

Vitamin deficiency (especially A, D, C), low-quality dry food, excessive activated carbon, stray voltage from equipment.

How is HLLE (Head and Lateral Line Erosion) treated?

Diet upgrade: Switch to high-quality varied diet: frozen mysis, brine shrimp, nori, Selcon vitamin soak. Add fresh garlic juice to food. Most cases improve within 4-8 weeks of diet change.

Can HLLE (Head and Lateral Line Erosion) be prevented?

Feed varied, high-quality diet from day one. Soak dry food in Selcon or VitaChem twice a week. Don't over-rely on activated carbon.

How fatal is HLLE (Head and Lateral Line Erosion)?

Mild but disfiguring; reversible if caught early

Should I treat in the display tank or quarantine?

Always treat in a separate quarantine or hospital tank. Most medications are toxic to coral, invertebrates, and live rock biology.

Related

Browse the full disease database for 45 aquarium conditions with treatment protocols, or check the care library for prevention-focused husbandry guides. Use our symptom matcher to rank likely diseases from observed signs, the water parameter checker to diagnose related water-quality issues, or the QT timeline calculator to plan a treatment schedule.