Black Spot Disease treatment protocol — controlling shell damage and secondary infection

1. Causes of black spots

3 main causes, often co-occurring:

• Mechanical shell damage — high density, rubbing, biting.
• Mineral deficiency — soft shells damage easily on moult.
• Vibrio harveyi / V. parahaemolyticus entry → melanin-secreting enzymes.
• Sometimes Fusarium fungi — especially with low DO, dirty bottom.

2. Treatment protocol

Apply simultaneously on 3 fronts:

• Water disinfection: single VIBRIO CLEAR (1 kg/3,000 m³), cut feed 30%.
• Shell recovery: feed CELL CANPHOS GOLD 10 ml/kg + QUICKSHELL GOLD 5 g/kg, 7 consecutive days.
• Immunity: CLEVER 5 g/kg + AQUAMOS 3 g/kg, 5 consecutive days.
• 24h after disinfection: reseed SOILMAX or MAX 4000.
• Boost DO ≥ 5 ppm, reduce density if possible (split ponds).

3. Recurrence prevention

• Routine mineral supplementation: CELL CANPHOS GOLD 5 ml/kg + QUICKSHELL GOLD 3 g/kg during peak moult.
• Track green Vibrio on TCBS weekly.
• Avoid DO < 4 ppm at night — increases stress + lets fungi grow.
• Frequent bottom siphoning late-cycle to cut accumulated organics.