Marine Ich (Cryptocaryon)
Complete guide to identification, timeline, and treatment
What is Marine Ich (Cryptocaryon)?
Marine Ich (Cryptocaryon irritans) is a common parasitic disease affecting saltwater fish. The parasite appears as small white spots on the fish's body, fins, and gills.
Symptoms
White spots on body and fins
Flashing or scratching against objects
Rapid breathing
Lethargy and loss of appetite
Clamped fins
Causes
Stress from poor water quality
Temperature fluctuations
New fish introduction
Overcrowding
Weakened immune system
Marine Ich (Cryptocaryon) Life Cycle & Timeline
Day 1-7
Parasite attaches to fish. White spots become visible. Fish shows signs of irritation and flashing.
Day 8-14
Parasite leaves the fish, reproduces in the substrate, then releases hundreds of free-swimming parasites.
Day 15-28
Parasite leaves the fish, reproduces in the substrate, then releases hundreds of free-swimming parasites.
Day 29+
New parasites seek hosts. This is the most effective treatment window.
Treatment Protocol
- Raise temperature to 82-86°F (28-30°C) to speed up parasite life cycle.
- Use copper-based medication — most effective for Marine Ich.
- Try hyposalinity: lower salinity to 1.009 specific gravity for 3-4 weeks.
- Perform daily 25% water changes to remove free-swimming parasites.
- Continue treatment for 10-14 days to break the complete life cycle.
- Quarantine all new fish for 30-45 days before adding to display tank.
Medication Options
- Copper Power – Chelated copper medication highly effective against Marine Ich when maintained at therapeutic levels (approximately 2.0–2.5 ppm).
- Seachem Cupramine – Copper-based treatment for marine fish. Use only in a quarantine tank and monitor copper levels carefully.
- Chloroquine Phosphate – Highly effective against Marine Ich and gentle on many marine fish. Not safe for reef aquariums.
- Ruby Reef Rally Pro – Can be used as a supportive treatment and in combination with quarantine protocols.
- Formalin – Effective for severe infections and freshwater dips under experienced supervision. Follow manufacturer instructions carefully.
- Copper Test Kit – Essential for accurately maintaining therapeutic copper concentrations during treatment.
Important
Always treat fish in a quarantine tank. Copper and hyposalinity treatments will harm invertebrates and live rock. Never treat your display reef tank directly.
