protozoan · freshwater

Hexamita (Hole-In-The-Head Parasite)

Hexamita is an internal protozoan parasite that causes white stringy feces, weight loss, and the classic "hole in the head" disease in cichlids. Treatment: metronidazole.

Severity: Moderate - treatable if caught early

Symptoms

Cause

Hexamita parasite enters via contaminated food or stress. Most common in cichlids (oscars, severums, discus, angelfish).

Treatment

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

Metronidazole (Metroplex). Most effective treatment. Dose per Seachem instructions for 7-10 days. Mix with food for internal infection.
API General Cure. Praziquantel + metronidazole combo. 7-day course.
Improved diet + vitamins. Soak food in Selcon vitamins. Reduces susceptibility.

Prevention

Pristine water, varied vitamin-rich diet, reduce activated carbon (depletes vitamins).

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.