Important aquarium checks
Ammonia in an Aquarium – Immediate Water Checks
See water-first actions for a high aquarium ammonia reading, including water changes, aeration, filter checks and retesting.
What to check first
- Perform an appropriate partial water change.
- Condition replacement tap water and increase aeration.
- Confirm the filter is working and retest after corrective action.
What you can do now
- Perform an appropriate partial water change.
- Condition replacement tap water.
- Increase aeration.
- Check whether the filter is running normally.
- Remove uneaten food and obvious decaying material.
- Reduce feeding temporarily.
- Do not replace all biological filter media at once.
- Test again after corrective action.
What may be contributing
- An immature or disrupted biological filter
- Excess feeding, stocking or decaying material
- Reduced filter operation
Questions that help narrow the problem
Are fish gasping, very inactive or otherwise distressed?
Yes · No · Not sure
Is the filter running, and was it recently cleaned or changed?
Running normally / no recent change · Recently cleaned or media changed · Stopped or not working normally · Not sure
Would you like to enter the exact ammonia and other water-test results?
Yes · No
Relevant tests and product guidance
These links come from the existing troubleshooting record. They do not replace water-quality correction or the current product label.
Avoid for now
- Do not treat an ammonia-binding conditioner as a replacement for correcting the underlying aquarium problem.
- Avoid replacing all biological media.
- Avoid continued heavy feeding.