🚑 Fish Are Dying: Advanced Emergency Playbook

⏱️ First 10 Minutes — Stabilize

1. 💨 Max oxygen now
   • Crank air and aim returns at the surface for ripples.
   • Lower water level slightly so HOB filters “waterfall.”
   • Turn off CO₂ (planted tanks).
   • No airstone? Point a powerhead at the surface; even scooping and pouring water from height helps in a pinch.
2. 💧 Detox immediately
   • Dose a conditioner that handles chlorine/chloramine and binds ammonia/nitrite (per label).
   • Stop feeding 24–48 hrs (waste reduction = oxygen back to your fish + lower ammonia production).
3. 🧪 Fast tests
   • NH₃/NH₄⁺, NO₂⁻, NO₃⁻, pH, KH, Temp.
   • Remove corpses and rotting organics right away.

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🕐 Next 60 Minutes — Correct Course

1. 🚿 Emergency water change
   • 40–50%, temp-matched, fully dechlorinated.
   • If NH₃ or NO₂⁻ still > 0, do 25–30% again in 12–24 hrs until 0/0.
2. 🔌 Hardware triage
   • Heater reading vs thermometer? (over/underheat kills fast)
   • Filter flowing? Impeller spinning? Prefilter clogged?
   • Canister: check O-rings/hoses for air leaks (microbubbles reduce pump efficiency).
   • Recent power outage? Treat it like a filter crash (see below).
3. 🧴 Suspect toxin?
   • Run fresh activated carbon / Poly-Filter (paint, aerosol, cleaners, smoke, pesticides, metals).
   • Keep heavy aeration while running chemical media.
4. 🧱 pH/KH crash (Old Tank Syndrome) signs
   • Very low pH, lethargy/gasping, high NO₃⁻, KH near zero.
   • Fix gradually: 15–20% water changes every 6–12 hrs + re-buffer KH in small steps. Avoid a big one-time jump.

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🧭 Root-Cause Fast Map

• 💥 Ammonia/Nitrite detected → New tank, filter crash, overcleaned media, overfeeding, hidden dead fish.
• 🌡️ Temperature off → Heater failure, room heat spike, cold top-off.
• ⚖️ pH/KH crash → Long intervals between changes + high nitrate.
• 🧴 Toxins → Household sprays, soap residue on hands, off-gassing décor, metals.
• 🪵 New substrate/wood/rocks → Leaching or dust; remove suspect item and polish water.

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🔬 Deep Diagnostics & What to Do

🧫 If NH₃ / NO₂⁻ > 0

• Water changes as above + extra aeration (detox products don’t add oxygen).
• Don’t clean bio-media right now; you need those bacteria.
• After stable: add bottled nitrifiers to bolster the biofilter.

⚖️ If pH/KH crashed

• Raise KH slowly (crushed coral, baking-soda-based buffers per label).
• Multiple small water changes; recheck pH between rounds.

🌡️ If temp shock

• Adjust ≤2°F (1°C) per hour toward target.
• Add aeration—warm water holds less O₂.

🧴 If chemical poisoning suspected

• Massive water change, carbon/Poly-Filter, continuous aeration.
• Remove the source; open room ventilation.
• Metallic contamination? Poly-Filter color change can hint at the culprit.

🧰 After antibiotics or a power outage

• Expect a biofilter setback. Feed sparingly, test daily, and reseed with nitrifiers.

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💊 When & How to Medicate (safely)

Fix water first. Stressed, hypoxic fish don’t tolerate meds well.

• ❄️ Ich → Heat (if species tolerate) + ich med per label.
• 🦠 Bacterial signs (fin rot, ulcers, red streaks) → broad-spectrum antibiotic.
• 🍄 True fungus → methylene blue/antifungal; salt only if species tolerate.
• 🪱 Flukes/parasites (flashing, excess slime) → praziquantel/metronidazole.
• 🧩 Look-alikes matter: White spots may be Epistylis (needs antibiotics, not ich meds).
  Treatment rules:
• Remove carbon/chem media, turn UV off during medication.
• Dose to label, maintain O₂, and finish the course.
• Quarantine if multiple meds are needed or species are sensitive (loaches, Corys, plecos, shrimp).

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🍽️ Supportive Care (speeds recovery)

• 🌑 Dim lights; minimize traffic near tank.
• 🍲 Resume tiny, high-quality feedings only when fish are responsive (vitamin-soaked frozen is great).
• 💨 Keep strong aeration through recovery.
• 🧪 Test daily for a week; log values.

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🧰 “Aquarium First-Aid Kit” (keep stocked)

• 🧴 Conditioner that binds ammonia/nitrite + dechlorinates.
• 💨 Spare air pump/airstone (battery backup if you can).
• 🧪 Liquid test kit; KH/GH strips for quick checks.
• 💊 Core meds: ich remedy, broad antibiotic, praziquantel/metronidazole, methylene blue, aquarium salt (know which fish are salt-sensitive).
• 🧊 Activated carbon/Poly-Filter for toxins.
• 🪣 QT tank, cycled sponge filter (seed in main tank), spare heater, nets/buckets dedicated to QT.

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📅 72-Hour Recovery Plan (template)

• Day 1: Emergency WC 40–50%, binders, max aeration; remove corpses/decay; test 2×/day.
• Day 2: If NH₃/NO₂⁻ > 0 → 25–30% WC; begin targeted meds only if symptoms persist and O₂ is good.
• Day 3: Reassess appetite/respiration; continue WCs until 0/0; keep lights low; re-seed bacteria if filter was compromised.

Improving: calmer breathing, schooling normally, interest in food.
Worsening: surface gasping despite O₂, rolling, hemorrhagic streaks—bigger WC, more O₂, reassess toxin/temperature/pH.

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🔒 Biosecurity (stop the cascade)

• 🪣 Separate tools for QT vs display.
• 🧼 Rinse hands/arms with water only before/after.
• 📦 Quarantine all new fish 2–4 weeks.
• 🧽 Clean prefilters weekly; don’t deep-clean all media at once.

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🧮 Nitrate-Based WC Planning (why schedule matters)

• Find weekly nitrate gain (ΔNO₃).
• If Δ ≈ 20 ppm/week:
  • 50% weekly keeps swing ~20→40 ppm (acceptable for most).
  • 25% weekly allows buildup ~45–60+ ppm (stress).
• Adjust % and frequency to hold your target (<20–30 ppm; <10 ppm for delicate species).

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🧩 Common Killer Timelines (helps pinpoint cause)

• Minutes–hours: toxins, heater stuck on, massive pH/temperature shock, O₂ crash (CO₂ mishap).
• Hours–day: ammonia/nitrite spike, severe aggression, overstocking with weak aeration.
• Days–weeks: chronic nitrate, parasites/bacteria, starvation after overstock stress.

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✅ After Stabilization — Hardening the System

• 📏 Right-size filtration (4–8× turnover; prefilter sponges).
• 📅 Consistent WC cadence (based on your ΔNO₃, not guesswork).
• 🍽️ Slight underfeeding beats overfeeding; remove leftovers.
• 🧪 Weekly testing until trends are boring (that’s good!).
• 🧱 Add redundancy: spare heater, spare air pump, battery backup if outages happen.