Ich: salt and temperature treatment

Ich (Ichthyophthirius multifiliis, "white spot") is the most common disease of aquarium fish. The pathogen is a protozoan. It's treatable — even beginners with the right protocol clear it in 2 weeks.

The parasite's life cycle

Understanding the cycle = understanding the treatment.

• Trophont — the stage inside the fish's skin. Under the scales. Visible as a white spot. At this stage, medications can NOT reach it.

• Tomont — the parasite leaves the fish, drops into the substrate, encapsulates. Also protected.

• Theront — the free-swimming stage. Looking for a new host. THIS STAGE IS VULNERABLE to treatment.

The cycle takes 3–4 days at 25 °C, 1–2 days at 30 °C. Treatment only works while the parasite is in its free-swimming stage.

Symptoms

• White grains 0.5–1 mm on scales and fins — like coarse sugar.

• Itching: fish rub against rocks and plants.

• Rapid breathing (if ich is in the gills — life-threatening).

• Withdrawn behavior, loss of appetite.

Treatment: heat + salt

Standard humane protocol (no chemistry):

Days 1–3: raising temperature

Raise temperature by 1 °C per day to 30 °C. At this temperature the parasite cycle speeds up (1–2 days instead of 4), and the parasite leaves protected stages faster.

DANGEROUS for discus, neons (at the upper edge of their tolerance). For them — no heat raise, salt only.

Days 1–14: salt

Table salt (NaCl, iodine-free) or specialized aquarium salt:

• 1 g/L — tolerated by most fish.

• 2 g/L — standard treatment dose.

• 3 g/L — last resort.

DANGEROUS: corydoras, tetras, kuhli loaches, botias — they tolerate salt poorly. For them — heat only or specialized medications.

Days 1–14: extra aeration

At high temperatures, oxygen solubility drops. An air pump is mandatory for the entire treatment.

Days 7–14: assessment

White spots should be gone. If not — extend or switch to chemical treatment.

Day 14+: returning to normal

Gradually lower the temperature (1 °C per day). Salt is removed via 20 % water changes every 3–4 days.

When chemistry is needed

If salt/heat doesn't work within 2 weeks, use:

• Malachite green — old and effective, but stains silicone and is toxic to scaleless fish. Doses per the instructions.

• Formalin-based products — for large fish with heavy infestation.

• Commercial mixes (Sera Costapur, JBL Punktol).

Prevention

• Quarantine new fish for 4 weeks.

• Stable temperature — sudden swings trigger ich.

• Strong immune system (clean water, varied diet).

Ich is 95 % treatable with early diagnosis. The main mistake is waiting for it to "go away on its own." The longer you wait, the more fish are infected, the harder the treatment.