Fusarium infection and damaged gills

01 · AquaGrow

What it is

Fusarium fungi can invade shrimp tissues, including the gills. Darkened lesions may accompany breathing difficulty and mortality. Similar colours occur for other reasons, so an appropriate laboratory must distinguish a true invasive infection from surface dirt or an unrelated organism.

Signs to watch for

• Localised or extensive dark patches appear in affected gills.
• Shrimp become weak or show difficulty maintaining normal activity.
• Feeding falls and deaths may occur; none of these observations alone confirms Fusarium.

Common causes

• Different Fusarium species and members of the Fusarium solani species complex have been investigated in penaeid shrimp. A black-gill appearance cannot identify a fungal species.
• Similar signs can have other causes: Ciliate or filamentous-bacterial fouling that traps dark debris. Gill injury from sediment, poor water quality, or chemical exposure.

How to confirm the cause

• Contact a qualified aquatic animal health professional and an appropriate diagnostic laboratory. Fresh lesion microscopy and histology (microscope examination of tissue) can show fungal threads invading tissue, rather than merely lying on its surface.
• Fungal culture with morphological or molecular identification may establish the organism. Ask the laboratory to relate its isolate to the lesions: finding Fusarium in pond water alone does not establish the cause of disease.

Prevention: your practical checklist

• Reduce shell and appendage injuries during sampling, grading, and transport.
• Clean and maintain inlet filtration equipment so trapped waste does not accumulate.
• Remove feed waste and manage bottom organic deposits throughout the crop.
• Maintain water quality and adequate oxygen to reduce additional gill stress.
• Keep equipment separate and include affected facilities in between-crop sanitation planning.

Keep learning

Farmer questions