Camallanus Worms: causes, symptoms and treatment

Camallanus Worms (Camallanus cotti and related) — etiology, symptoms, diagnosis, active-substance medication, recovery and prevention; mortality without treatment: high.

Overview

Live-bearing intestinal nematode protruding red worms from the anus. Highly common in livebearers, gouramis, and discus from contaminated stock. Causative agent: Camallanus cotti and related. Transmission: direct-contact. Incubation: 14-60 days. Reported mortality without treatment: high.

Symptoms

red worms protruding from vent
swollen belly
weight loss
loss of color
stringy white faeces
lethargy

Causes

Outbreaks are typically triggered by chronic stress, poor water quality, temperature swings, overcrowding, or the introduction of unquarantined fish. The pathogen spreads via direct contact with infected fish or carriers.

Diagnosis

Diagnosis is based on clinical signs (visible worms, white stringy feces, weight loss despite eating) and microscopic examination of fresh faeces for eggs or fragments of Camallanus cotti and related.

Treatment

Effective treatment requires isolating affected fish in a quarantine tank, identifying the pathogen, administering the appropriate active substance at the correct dose and duration, and supporting recovery with stable water parameters and nutrition.

Step 1: Quarantine

Set up a bare-bottom quarantine tank with a mature sponge filter, heater, and aeration. Match temperature and pH to the display tank, and acclimate fish slowly. A bare bottom simplifies daily siphoning and prevents medication from being absorbed by substrate.

Step 2: Medication

Levamisole. Levamisole HCl 2 ppm in main tank, blackout 24h, 70% water change next day; repeat every 7 days x 3 cycles. (duration: 21 days)
Fenbendazole. Fenbendazole 2 mg/L in food or water for 3 days, repeat after 14 days; safer for invertebrate-tolerant tanks than levamisole. (duration: 21 days total)

Step 3: Recovery

After medication, perform a 30-50% water change and run fresh activated carbon for 24-48 hours to remove residues. Continue feeding a high-quality, varied diet with vitamins and immunostimulants. Reintroduce fish to the display tank only after at least one week without recurrence of symptoms.

Prevention

quarantine new livebearers and gouramis
deworm prophylactically with levamisole
avoid mixing fish from multiple sources
do not feed wild-collected copepods