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Cycle Chemistry
Ammonia (NH3/NH4+)
The primary nitrogenous waste of fish - highly toxic and the number one killer in newly-set-up aquariums.
Unit: ppm Code: NH3
📖 Overview
Fish excrete ammonia constantly through their gills. Uneaten food and decaying organic matter also produce it. In an established aquarium, nitrifying bacteria convert ammonia to nitrite, then to less-toxic nitrate. But in a new tank - before those bacteria have colonized - ammonia accumulates rapidly. Even 0.25 ppm damages gill tissue; 1+ ppm can be fatal within hours.
❓ Why It Matters
Ammonia burns gills, causes internal bleeding, weakens the immune system, and kills fish. It is the single most common cause of new tank fish loss ("new tank syndrome").
🧪 Testing Methods
API Ammonia Test Kit (most common). Seachem Ammonia Alert (in-tank monitor). Salifert Ammonia (reef).
📉 How to Lower
Immediate: 25-50% water change. Use ammonia detoxifier (Prime, AmQuel). Longer-term: complete the nitrogen cycle before adding fish. Reduce feeding. Remove dead fish/plants.
⚠️ Symptoms of Imbalance
Red or bloody gills, gasping at surface, lethargy, refusing food, hemorrhaging on body.
🐟 Species with Specific Requirements