🐟 Fish Lice & Leeches: Vet Guide 2025 🩺

By Dr Duncan Houston BVSc – Small crustaceans and annelids like lice (Argulus) and leeches can infest fish, causing irritation, disease risk, and anemia. This 2025 vet-approved guide explains how to spot them, treat safely, and prevent future outbreaks.

📌 What Are Fish Lice & Leeches?

Fish lice (e.g., Argulus spp.) are rod‑shaped crustaceans that attach to skin, fins, or gills using hooked claws, feeding on blood and tissue :contentReference[oaicite:2]{index=2}. Leeches (e.g., Myzobdella lugubris) are annelid worms that similarly suck blood and often spread other parasites like Cryptobia :contentReference[oaicite:3]{index=3}.

⚠️ Signs of Infestation

• Visible parasites on skin, gills, or fins – small, flat lice or worm-like leeches :contentReference[oaicite:4]{index=4}
• Flashing or rubbing against objects
• Red, ulcerated skin or inflamed fins
• Gasping, lethargy, and weight loss due to anemia :contentReference[oaicite:5]{index=5}
• Surface swimming with exposed dorsum in leech‑infested fish :contentReference[oaicite:6]{index=6}

🔬 How Vets Diagnose

• Direct visual inspection with magnification
• Wet-mount microscopy to check gills and skin scrapings
• Observation of behavior (flashing, gasping, lethargy)
• Tank history including new fish or plants

🛡️ Treatment Options

1. Physical Removal

Use tweezers or a moist cotton swab in a quarantine tank to gently remove visible lice or leeches :contentReference[oaicite:7]{index=7}.

2. Medicinal Baths and Baths

• Trichlorfon (Dylox, Clout): Effective against lice and leeches in freshwater—follow label and tank parameters carefully :contentReference[oaicite:8]{index=8}.
• Organophosphates: Effective but toxic to invertebrates—avoid if you keep snails or shrimps :contentReference[oaicite:9]{index=9}.
• Diflubenzuron: Targets parasite molts (lice, anchor worms) – water must remain quarantined for 28 days :contentReference[oaicite:10]{index=10}.
• Microbe‑Lift Lice & Anchor Worm: OTC option favored by hobbyists—added with each water change; disrupting molts reduces infestation :contentReference[oaicite:11]{index=11}.

3. Quarantine Protocols

Move infested fish to quarantine tank before treatment. Treat the main tank simultaneously to prevent reinfestation. Repeat treatment after one molting cycle (~2 weeks) for effectiveness :contentReference[oaicite:12]{index=12}.

4. Environmental Control

• Clean and disinfect tanks, décor, and equipment before reuse
• Quarantine new fish and plants for at least 2–4 weeks
• Maintain excellent water quality to bolster fish immune resilience

🐾 Safety & Fish Welfare Considerations

• Avoid harsh chemicals in planted, shrimp, or snail tanks
• Match treatment to life stage—residuals may harm sensitive invertebrates
• Support fish with gentle water flow, aeration, and immune-enhancing supplements
• Monitor closely during and after treatment; use Ask A Vet for tailored advice

🩺 Vet-Approved Care Tips 2025

• Quickly isolate any fish showing flashing, rubbing, or visible parasites
• Combine removal and medicinal baths for faster relief
• Repeat treatments after two weeks to catch new hatchlings
• Disinfect everything—nets, filter media, décor—after use in infected tanks
• Use quarantine for new arrivals and dip plants before adding them to display tanks
• Use Ask A Vet app to report photos, signs, and water data to aquatic vets instantly

📊 Prevention Is Key

• Quarantine every new fish and plant for 2–4 weeks
• Avoid sourcing from wild or untreated ponds
• Maintain stable water quality and low stress environments
• Use parasite-disrupting treatments periodically if lice are common in area tanks (e.g., Microbe‑Lift)

🔗 About Ask A Vet

The Ask A Vet app offers 24/7 access to aquatic vets for parasite concerns. Upload tank parameters and images to receive tailored treatment protocols, dose guidance, and quarantine plans. Our AquaCare line includes water conditioners and fish protectants to support recovery and prevention. Download today to keep your fish healthy and lice-free in 2025! 🐠📲💙