Parasitic
🔴 Fatal
✓ Treatable
Ichthyobodo (Costia) Infection
🦠 Ichthyobodo necator (formerly Costia necatrix) · Ichthyobodonidae (Kinetoplastida)
📋 Overview
Ichthyobodo is one of the most common and dangerous parasites of freshwater aquaculture fry. The biflagellate parasite attaches to epithelial cells and feeds on host cytoplasm, causing rapid tissue destruction. It thrives in cool water (5–20 °C) and spreads rapidly through infected fry batches.
📊 Key Facts
Causative Agent
Ichthyobodo necator (formerly Costia necatrix)
Agent Family
Ichthyobodonidae (Kinetoplastida)
Geographic Range
Worldwide in fresh and slightly brackish water
Transmission Routes
Direct fish-to-fish contact; free-swimming zoites
Primary Host
Salmonids, cyprinids, many freshwater species
Vaccine
✗ None / Experimental
🩺 Clinical Signs
Grey-blue skin sheen, excessive mucus, fin clamping, hanging at surface, skin erosion, haemorrhagic patches, acute mortality in juveniles.
🔬 Symptoms
🔬
Grey-blue skin sheen
Integumentary Acute
🔬
Haemorrhagic skin patches
Integumentary Acute
🔬
Fin clamping
Integumentary Subacute
🔬
Hanging at surface
Respiratory Acute
🧪 Diagnosis
Wet mount of skin scrape (small comma-shaped flagellates, ~8–15 µm), gill examination.
💊 Treatment
Formalin (most effective), salt, copper sulphate, acriflavine.
🛡️ Prevention
ℹ️ Prevention is the most effective strategy for managing this disease in aquaculture and aquarium settings.
Screen broodstock, quarantine, treat incoming eggs, optimise temperature.