Marine Ich

🦠 Marine Ich (Cryptocaryon irritans)

1. Name/Common Name

• Common Name: Marine Ich, Saltwater Ich, White Spot Disease

• Scientific Name: Cryptocaryon irritans

2. Category

• Protozoan Parasite

3. Description

• Single-celled ciliated protozoan

• Appears as tiny white cysts or bumps on fish skin, fins, and gills

• Often compared to grains of salt or sugar

4. What They Affect

• All marine fish, especially tangs, clownfish, and wrasses

• Can affect both reef and fish-only systems (though corals/inverts aren’t infected directly)

5. Size

• Cysts on fish: ~0.3 to 0.5 mm (visible to the naked eye)

• Trophonts (feeding stage) burrow into tissue

• Tomonts (reproductive cysts) can be found on substrate and rocks

6. Reproduction Rate

• High

• Lifecycle: ~6–10 days at 25°C (77°F), but varies with temperature

• One tomont can release hundreds of free-swimming theronts (infectious stage)

7. Contagiousness

• Highly contagious among fish

• Spreads through water, nets, fish transfers, even aerosols from splashing

• Can spread tank-wide quickly if left untreated

8. Symptoms/Signs

• White spots on skin, fins, or eyes

• Rapid breathing or gill movement

• Scratching (flashing) against rocks or substrate

• Lethargy, loss of appetite, hiding

• Fin clamping or secondary infections (bacterial)

9. Environmental Triggers

• Stress from poor water quality, aggression, or new tankmates

• Sudden temp/salinity changes

• Often introduced from unquarantined fish

10. Prevention

• Strict quarantine of all fish (4–6 weeks minimum)

• Freshwater dips and observation before introduction

• UV sterilizer may help limit spread (but not eradicate)

• Avoid overstocking or mixing aggressive tankmates

11. Treatment Options

In a separate hospital tank only (NOT reef-safe):

• Copper treatments (e.g., Cupramine, Copper Power)

• Chloroquine phosphate (requires precise dosing)

• Hyposalinity (1.009–1.010 SG) for several weeks

• Tank transfer method (TTM): Moving fish every 72 hours to prevent reinfection

For display tank:

• Fallow period of 6–8 weeks (fish-free) to break parasite lifecycle

• Maintain stable conditions and feed fish well during treatment

12. Prognosis

• Good if caught early and treated correctly

• Fatal if left untreated, especially in heavily infested systems

• Can remain dormant for short periods, then reappear under stress

13. Difficulty to Eliminate

• 🔥🔥🔥 Very High in reef systems

• Must treat all fish and go fallow in display to fully eradicate

14. Additional Notes

• Often confused with Brooklynella or Velvet (Amyloodinium)—both far more aggressive

• Do not treat with copper or formalin in your display tank—kills inverts and corals

• Can coexist with fish subclinically, but will flare under stress