Fritz Expel-F | Flubendazole Anthelmintic Treatment

Active ingredient: Flubendazole (benzimidazole anthelmintic)

Flubendazole is a benzimidazole anthelmintic — it binds selectively to β-tubulin in parasite cells, inhibiting microtubule polymerization. This disrupts intracellular transport and nutrient absorption in parasitic worms, causing their death. It has no antifungal, antibacterial, or antiprotozoal activity. Expel-F is a dewormer, not an antifungal.

Target Parasites

What Expel-F Does NOT Treat

• Protozoan parasites — no effect on ich (Ichthyophthirius multifiliis), velvet (Oodinium), Hexamita, or Spironucleus
• Monogenean flukes (Dactylogyrus, Gyrodactylus) — flubendazole has limited activity against flukes at standard aquarium doses
• Fungal or bacterial infections — no activity against these

Signs of Internal Parasites

• White, stringy, or mucus-laden feces
• Hollow belly despite normal or increased appetite
• Gradual wasting and progressive weight loss
• Fish rubbing abdomen against substrate
• Camallanus specifically: orange or red worm tips visibly protruding from the vent (anus), most easily spotted at night or when the fish is stressed

Invertebrate & Plant Safety

• Safe for shrimp and snails at recommended doses — flubendazole's β-tubulin binding mechanism is selective to helminths and does not affect invertebrates via nAChR pathways the way levamisole does
• Safe for planted tanks — does not harm aquatic plants, unlike levamisole (Expel-P) which can affect some sensitive species

Treatment Protocol

• Remove activated carbon during treatment
• Dose per label directions; works systemically when the fish ingests the medication
• Best delivered as a food soak — mix into a small amount of gel food or food paste to ensure each fish ingests the medication directly rather than relying on waterborne uptake
• Retreat in 2–3 weeks — flubendazole kills adult worms but does not destroy eggs; a second dose after eggs hatch is required to fully eliminate the infestation