API Freshwater & Saltwater Ammonia Test Kit – Aquarium Water Testing

Ammonia is, without question, the number one killer of freshwater fish – and the worst part is, you can't see it coming. Fish constantly release ammonia through their gills, urine, and waste, and it builds up further from uneaten food and decaying organic matter. Small amounts stress fish. Large amounts kill them. The only way to know what's actually happening in your water is to test it – which is exactly what the API Ammonia Test Kit is built for.

Trusted for over 50 years, API have built their reputation on research-driven aquarium care, and this test kit is a core part of that. It includes everything you need: two liquid dropper bottles, a glass test tube with snap-tight cap, two colour charts, and clear instructions on how to test and correct unsafe ammonia levels. Suitable for both freshwater and saltwater aquariums, reading levels from 0 to 8 mg/L.

Key Features & Benefits

• Detects Ammonia Levels 0–8 mg/L: A wide testing range to catch problems early, before they become dangerous.
• Suitable for Freshwater & Saltwater: One kit works across both tank types.
• Complete Testing Kit: Includes dropper bottles, a glass test tube with snap-tight cap, two colour charts, and clear instructions.
• Easy to Read Results: Colour-matching charts make interpreting results straightforward, even for first-time testers.
• Includes Guidance on Correcting Problems: Instructions cover not just how to test, but how to address unsafe ammonia levels if found.
• 50+ Years of API Research: Backed by decades of aquarium science and product development.
• Works Alongside the Wider API Range: Designed to be used in conjunction with other API treatments for algae control, beneficial bacteria, and disease management.

Why We Rate This

Ammonia poisoning is one of the most common – and most preventable – causes of fish loss, particularly in new aquariums going through their nitrogen cycle. The trouble is, ammonia is completely invisible. Your tank can look perfectly clear and healthy while ammonia levels are quietly climbing to dangerous levels underneath. Regular testing is the only reliable way to catch that before it becomes a problem.

We’d especially recommend testing several times a week for the first 4–6 weeks of a new aquarium, when the beneficial bacteria that naturally process ammonia haven’t yet established themselves. After that, weekly testing is a sensible habit to maintain, or whenever you notice anything off with your fish’s behaviour or appearance. A simple test kit like this one takes the guesswork out of water quality entirely.

What's Included

• Two liquid dropper bottles
• Glass test tube with snap-tight cap
• Two colour comparison charts
• Easy-to-read testing and troubleshooting instructions

Testing Guide

Use several times a week for 4–6 weeks when setting up a new aquarium, then switch to weekly testing for ongoing monitoring, or test immediately if you notice any signs of a problem. Always follow the included instructions for accurate results.

Suitable For:

• Freshwater and saltwater aquariums
• New aquarium setups going through their nitrogen cycle
• Tropical community fish, cichlids, goldfish, and other freshwater species
• Owners wanting to proactively monitor water quality

Know what's really in your water – add the API Ammonia Test Kit to your basket today.