What is an ammonia spike in aquariums?
An ammonia spike occurs when ammonia accumulates faster than beneficial bacteria can convert it, making the water toxic to fish and invertebrates.
Why ammonia spikes are dangerous
Ammonia is highly toxic and can:
- Burn gills and skin
- Cause rapid breathing and lethargy
- Lead to internal organ damage
Even low concentrations can be fatal with prolonged exposure.
Common causes of ammonia spikes
- Overfeeding and excess uneaten food
- Overstocking fish
- Dead fish or decaying plants
- New or uncycled aquariums
- Improper cleaning of biological filter media
Safe ammonia levels
- Freshwater aquariums: 0 ppm
- Marine aquariums: 0 ppm
Any detectable ammonia requires immediate action.
Ammonia in the nitrogen cycle
Ammonia is the first stage of the nitrogen cycle:
A fully cycled aquarium converts ammonia continuously, preventing spikes.
How to fix and prevent ammonia spikes
- Perform partial water changes
- Reduce feeding temporarily
- Remove decaying organic matter
- Avoid rinsing filter media with tap water
- Ensure proper tank cycling before adding livestock
Regular water testing is essential for early detection.