What are the symptoms of Freshwater Ich?

Pinpoint white spots 0.5-1 mm across the body and fins, like scattered salt grains, increasing in number over days; Frequent flashing, rubbing the body against glass, wood or gravel; Rapid gill movement and occasional gasping near the surface or filter outlet; Reduced appetite, hiding, clamped fins, and in severe cases red streaks on the body. It usually starts with: New fish added without quarantine, carrying tomonts or theronts into the tank; Sudden temperature drops or large day/night swings suppressing the immune system; Elevated ammonia or nitrite, or long-term overcrowding; Water changes where the new water differs from tank water by more than 2 °C.

How do you treat Freshwater Ich?

In order: 1. Isolate affected fish (Move affected fish into a hospital tank with their own net and tools so the parasite is not spread on shared equipment; start raising the display tank temperature at the same time.) 2. Change water and clear the substrate (Change 30-50% of the water with temperature-matched water and siphon out leftover food and waste. Part of the life cycle is spent as tomonts on the substrate, so cutting organic debris lowers reinfection pressure.) 3. Raise the temperature to 30-32 °C (Raise to 30-32 °C no faster than 1 °C per hour and hold for 10-14 days, with a heater plus a separate controller. Heat accelerates the parasite life cycle so it enters the stage that can be killed; it does not cook the parasite.) 4. Add salt to 0.3-0.5% (Dissolve 3-5 g of non-iodised salt per litre, added in 2-3 portions over a day. Scaleless fish such as loaches, plecos and corydoras cannot tolerate salt - use heat alone for them.) 5. Medicate only if heat and salt fail (Only if new spots keep appearing after 3-5 days, treat in the hospital tank with malachite green, methylene blue or a copper-based product. These harm the biofilter, and copper is lethal to shrimp, snails and live rock life, so it must never go into the display tank.) 6. Observe for a week after treatment (Keep the fish under observation for 7 more days after all spots are gone before returning it, and re-acclimate temperature and water on the way back to avoid a second stress event.)

What medication treats Freshwater Ich?

Malachite green: Hospital tank only. Follow the label; a common regimen is 0.1-0.2 mg/L with alternate-day redosing for 7-10 days. It is toxic to nitrifying bacteria and invertebrates, carries toxicity and carcinogenicity concerns for fish, and is restricted in many regions - avoid it if you can.; Methylene blue: Hospital tank only. Used as a short bath at the label dose (a few drops per 10 L). It affects plants and the biofilter; change water and run activated carbon afterwards.; Copper sulfate / copper-based ich remedies: Hospital tank only, dosed to the label with a copper test kit. Copper is lethal to corals, shrimp, snails, starfish and live rock life, so it must never enter a reef or invertebrate tank, and should not be combined with formalin.

G-04 / 01Freshwater

Freshwater Ich白点病

Act now. A properly treated tank comes under control in 2-3 weeks, but once the gills are heavily infested mortality is high - do not wait and see.

Illustration to come

G-04 / 01 · Freshwater Ich

SpecificationsDisease atlas

Cause: Parasite
Severity: Severe
Contagion: Highly contagious
Corals / inverts: Not safe
Also known as: White spot disease、Ichthyophthirius multifiliis

Symptoms

Pinpoint white spots 0.5-1 mm across the body and fins, like scattered salt grains, increasing in number over days
Frequent flashing, rubbing the body against glass, wood or gravel
Rapid gill movement and occasional gasping near the surface or filter outlet
Reduced appetite, hiding, clamped fins, and in severe cases red streaks on the body

Typical triggers

— New fish added without quarantine, carrying tomonts or theronts into the tank
— Sudden temperature drops or large day/night swings suppressing the immune system
— Elevated ammonia or nitrite, or long-term overcrowding
— Water changes where the new water differs from tank water by more than 2 °C

Treatment, in order

1 · IsolateIsolate affected fishMove affected fish into a hospital tank with their own net and tools so the parasite is not spread on shared equipment; start raising the display tank temperature at the same time.
2 · Water changeChange water and clear the substrateChange 30-50% of the water with temperature-matched water and siphon out leftover food and waste. Part of the life cycle is spent as tomonts on the substrate, so cutting organic debris lowers reinfection pressure.
3 · HeatRaise the temperature to 30-32 °CRaise to 30-32 °C no faster than 1 °C per hour and hold for 10-14 days, with a heater plus a separate controller. Heat accelerates the parasite life cycle so it enters the stage that can be killed; it does not cook the parasite.
4 · SaltAdd salt to 0.3-0.5%Dissolve 3-5 g of non-iodised salt per litre, added in 2-3 portions over a day. Scaleless fish such as loaches, plecos and corydoras cannot tolerate salt - use heat alone for them.
5 · MedicationMedicate only if heat and salt failOnly if new spots keep appearing after 3-5 days, treat in the hospital tank with malachite green, methylene blue or a copper-based product. These harm the biofilter, and copper is lethal to shrimp, snails and live rock life, so it must never go into the display tank.
6 · ObserveObserve for a week after treatmentKeep the fish under observation for 7 more days after all spots are gone before returning it, and re-acclimate temperature and water on the way back to avoid a second stress event.

The standard treatment uses copper or formalin, which is lethal to corals, shrimp, snails and everything on live rock. Treat in a quarantine tank only, and leave the display tank fallow for the full period above before returning the fish.

Medications and cautions

Malachite green: Hospital tank only. Follow the label; a common regimen is 0.1-0.2 mg/L with alternate-day redosing for 7-10 days. It is toxic to nitrifying bacteria and invertebrates, carries toxicity and carcinogenicity concerns for fish, and is restricted in many regions - avoid it if you can.
Methylene blue: Hospital tank only. Used as a short bath at the label dose (a few drops per 10 L). It affects plants and the biofilter; change water and run activated carbon afterwards.
Copper sulfate / copper-based ich remedies: Hospital tank only, dosed to the label with a copper test kit. Copper is lethal to corals, shrimp, snails, starfish and live rock life, so it must never enter a reef or invertebrate tank, and should not be combined with formalin.

Prevention

Quarantine new fish for 2-4 weeks and confirm they are spot-free before adding them to the display tank
Measure the temperature gap before a water change and match new water to within 1 °C of the tank
Do not share nets or siphon hoses between the quarantine tank and the display tank
Clean the substrate and filter media regularly so organic debris does not accumulate

Frequently asked questions

What are the symptoms of Freshwater Ich?: Pinpoint white spots 0.5-1 mm across the body and fins, like scattered salt grains, increasing in number over days; Frequent flashing, rubbing the body against glass, wood or gravel; Rapid gill movement and occasional gasping near the surface or filter outlet; Reduced appetite, hiding, clamped fins, and in severe cases red streaks on the body. It usually starts with: New fish added without quarantine, carrying tomonts or theronts into the tank; Sudden temperature drops or large day/night swings suppressing the immune system; Elevated ammonia or nitrite, or long-term overcrowding; Water changes where the new water differs from tank water by more than 2 °C.
How do you treat Freshwater Ich?: In order: 1. Isolate affected fish (Move affected fish into a hospital tank with their own net and tools so the parasite is not spread on shared equipment; start raising the display tank temperature at the same time.) 2. Change water and clear the substrate (Change 30-50% of the water with temperature-matched water and siphon out leftover food and waste. Part of the life cycle is spent as tomonts on the substrate, so cutting organic debris lowers reinfection pressure.) 3. Raise the temperature to 30-32 °C (Raise to 30-32 °C no faster than 1 °C per hour and hold for 10-14 days, with a heater plus a separate controller. Heat accelerates the parasite life cycle so it enters the stage that can be killed; it does not cook the parasite.) 4. Add salt to 0.3-0.5% (Dissolve 3-5 g of non-iodised salt per litre, added in 2-3 portions over a day. Scaleless fish such as loaches, plecos and corydoras cannot tolerate salt - use heat alone for them.) 5. Medicate only if heat and salt fail (Only if new spots keep appearing after 3-5 days, treat in the hospital tank with malachite green, methylene blue or a copper-based product. These harm the biofilter, and copper is lethal to shrimp, snails and live rock life, so it must never go into the display tank.) 6. Observe for a week after treatment (Keep the fish under observation for 7 more days after all spots are gone before returning it, and re-acclimate temperature and water on the way back to avoid a second stress event.)
Is Freshwater Ich contagious, and how urgent is it?: Contagion: highly contagious. Severity: severe. Cause: parasite. Act now. A properly treated tank comes under control in 2-3 weeks, but once the gills are heavily infested mortality is high - do not wait and see.
What medication treats Freshwater Ich?: Malachite green: Hospital tank only. Follow the label; a common regimen is 0.1-0.2 mg/L with alternate-day redosing for 7-10 days. It is toxic to nitrifying bacteria and invertebrates, carries toxicity and carcinogenicity concerns for fish, and is restricted in many regions - avoid it if you can.; Methylene blue: Hospital tank only. Used as a short bath at the label dose (a few drops per 10 L). It affects plants and the biofilter; change water and run activated carbon afterwards.; Copper sulfate / copper-based ich remedies: Hospital tank only, dosed to the label with a copper test kit. Copper is lethal to corals, shrimp, snails, starfish and live rock life, so it must never enter a reef or invertebrate tank, and should not be combined with formalin.
Is the treatment for Freshwater Ich safe for corals and inverts?: No. The standard treatment (copper or formalin based) is lethal to corals, shrimp, snails and everything on live rock. Treat in a quarantine tank only, and leave the display tank fallow for the full period given above.