Ich (White Spot) Treatment in Tropical Aquariums: UK Guide

Quick action plan

If you see white spots on your fish RIGHT NOW:

1. Raise temperature to 28-30 °C gradually (1 °C per 6 hours)
2. Buy ich medication — Esha 2000, Waterlife Protozin, or eSHa Exit (UK shops have these)
3. Dose per bottle instructions — usually one full dose every 24 hours for 5-7 days
4. Increase aeration — warm water holds less oxygen; add an airstone
5. Reduce feeding to 50% — less waste, less stress
6. Continue for 14 days even if spots disappear by day 5 — the parasite cycle takes 14 days at 28 °C

Don't panic. Caught early, 95% of fish recover.

What ich looks like (identification)

Ich (also spelt "ick") is caused by the parasite Ichthyophthirius multifiliis.

Visual signs:

• Tiny white spots, like grains of salt or sugar, on body and fins
• Spots concentrated on fins first, then spread to body
• Cotton-like or fluffy spots = different problem (fungus, not ich)
• Slimy white film over the fish = advanced ich (or columnaris — get a second opinion)

Behavioural signs:

• Flashing — fish dart and rub against decor, gravel, or plants
• Clamped fins (held tight against body)
• Lethargy, hiding
• Loss of appetite
• Gasping at the surface (gills affected)

Timeline:

• Days 1-3: A few visible spots
• Days 3-7: More spots; fish flashing constantly
• Days 7-14: Severe coverage, lethargy, breathing distress
• Day 14+ untreated: Death

The parasite has a 3-stage lifecycle:

1. Trophont (visible white spot on fish) — feeding stage, 3-7 days
2. Tomont (drops off fish, attaches to substrate) — reproductive stage, 1-3 days
3. Theront (free-swimming) — searches for new fish to infect, 1-2 days; KILLED by medication

You can only kill ich during the free-swimming theront stage. This is why treatment takes 14 days minimum.

Why ich appears

Ich is opportunistic — it preys on stressed fish. Common triggers:

1. Temperature drop — heater failure, cold water change, draught from open window
2. New fish introduced without quarantine — most common entry point
3. Poor water quality — high ammonia/nitrite weakens immunity
4. Tank not fully cycled — new tank syndrome
5. Stressful tank mates — bullying, fin-nipping
6. Plants or decor from infected source

Healthy fish in stable warm well-cycled tanks rarely get ich. When ich strikes, fix the underlying stressor too.

Treatment options (UK)

Option 1: Heat + medication (most reliable, mixed-species safe)

1. Raise temperature from current to 28-30 °C over 12-24 hours (1 °C per 6 hours — too fast = stress)
2. Add medication: Esha 2000 (best for community), Waterlife Protozin, or eSHa Exit
3. Add airstone — warm water = less dissolved oxygen
4. Dose per bottle instructions for 7-10 days
5. Don't carbon filter during treatment — carbon removes medication
6. Water change 25% between doses if instructions say so

Works for: community tanks, mixed species, sensitive fish

Option 2: Heat + salt (for hardy fish only)

1. Raise temperature to 28-30 °C
2. Add aquarium salt: 1 tablespoon (15g) per 20 L of water
3. Pre-dissolve salt in a jug of tank water, then add to tank gradually
4. Add airstone
5. Continue for 10-14 days
6. After treatment: water changes to dilute salt over a week

Do NOT use for: corydoras, kuhli loaches, most tetras, scaleless fish (loaches generally), shrimp, snails

Option 3: Heat alone (mild cases, hardy fish)

1. Raise temperature to 30 °C
2. Maintain for 14 days minimum
3. Maximum aeration

The parasite can't reproduce above 30 °C. This works for some hardy species (danios, platies) in mild infections. Don't use for sensitive species or severe outbreaks.

Species-specific treatment notes

When in doubt: half-dose medication + heat. Slower but safer.

Common ich treatment mistakes

Mistake 1: Stopping treatment when spots disappear

Why it fails: Spots vanish around day 5-7 because the trophont stage drops off. But tomont eggs are still on substrate, releasing free-swimming theronts. Stop treatment now → outbreak in 2 weeks.

Fix: Treat for FULL 14 days even after spots vanish.

Mistake 2: Carbon filter left in during treatment

Why it fails: Activated carbon absorbs medication out of the water within hours. Treatment becomes useless.

Fix: Remove carbon during treatment. Replace it AFTER full course.

Mistake 3: Raising temperature too fast

Why it fails: Going from 25 °C to 30 °C in an hour shocks fish. Stresses them more, reduces survival.

Fix: Raise 1 °C per 4-6 hours. Takes 24-30 hours total — that's fine.

Mistake 4: Treating without raising temperature

Why it fails: Most ich medications work best at warmer temperatures. At 25 °C the parasite cycle takes 21+ days; at 30 °C it takes 7 days.

Fix: Raise temperature regardless of medication.

Mistake 5: Adding new fish during treatment

Why it fails: New fish stress the tank, get infected immediately, and may carry it back into other tanks.

Fix: No new fish for 30 days after treatment ends. Quarantine all future additions.

Prevention

90% of ich outbreaks come from new fish. Prevent ich:

1. Quarantine all new fish in a separate tank for 14-21 days
2. Stable temperature — replace heater every 2-3 years
3. Stable parameters — no sudden water changes
4. Heated tank during winter in unheated rooms
5. Don't share nets/equipment between tanks without disinfection
6. Buy fish from healthy-looking tanks — if you see ich at the shop, don't buy ANY fish from that tank

Recovery timeline

After successful treatment:

• Day 14: Spots gone, fish behaviour back to normal
• Day 21: Resume normal feeding
• Day 30: Replace carbon filter, do large water change to clear medication residue
• Day 30-60: Watch for any returning spots; sometimes a small re-emergence

Fish that survived ich generally have improved immunity to future infections.

Summary

Ich is curable. Heat + medication for 14 full days. Don't stop early. Don't add new fish for a month after. Catch it early at first spot and 95% of fish recover.

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