Why Shrimp Die Before Fish
Written 2026-10-16
Cherry shrimp die before neon tetras in the same tank because shrimp have a much lower nitrite tolerance than fish. In the Water Kiwoogi simulator, we added 8 neon tetras and 10 cherry shrimp to a brand-new 60cm tank on day one and ran 30 days. Nitrite climbs to a test-kit peak of 0.91ppm between days 6 and 8, and by then 2 of the 10 cherry shrimp have died. The 8 neon tetras that lived through the exact same water all survive.
Same water, so why only the shrimp?
Converting Water Kiwoogi’s published tolerance values into test-kit numbers, cherry shrimp start dying around 0.29ppm nitrite, while neon tetras hold out to roughly 0.66ppm — less than half the fish’s threshold. So while the nitrite spike during cycling is still tolerable for the tetras, it’s already in toxic territory for the shrimp. Small invertebrates with simpler gills are usually the first to react to water-quality swings, and shrimp are no exception.
| Species | Nitrite toxicity threshold (test-kit ppm) |
|---|---|
| Cherry shrimp | 0.29ppm |
| Neon tetra | 0.66ppm |
Running it out to 30–50 days
Same 60cm tank, same bacteria starter on day one, same weekly 25% water change starting on day 10 — only the stocking schedule changes.
| Stocking | Peak nitrite (ppm) | Neon tetra survival | Cherry shrimp survival |
|---|---|---|---|
| Both added day one | 0.91 | 8 / 8 | 8 / 10 (deaths on days 6 and 8) |
| Tetras only, day one (control) | 0.43 | 8 / 8 | – |
| Tetras day one, shrimp day 35 | 0.43 | 8 / 8 | 10 / 10 |
This tank finishes cycling on day 10 — the day ammonia and nitrite both settle to a test-kit zero and stay there. The two shrimp deaths on days 6 and 8 land right in the last stretch before that, exactly when nitrite is at its highest. Add the shrimp on day 35 instead, well after the tank has cycled, and all 18 animals — tetras and shrimp alike — make it through.
What this means for your tank
Shrimp and other invertebrates are more sensitive than fish, so it’s safer to hold off on adding them to a brand-new tank until cycling is finished. Wait until your ammonia and nitrite test kits both read zero, or buy shrimp for a tank that’s already cycled. If shrimp start dying while the fish in the same tank look fine, don’t assume the water is okay — test for nitrite, and talk to your local fish store or a specialist if you’re not sure what to do next.
The button below runs the exact tank from this guide — a 60cm tank with 8 neon tetras and 10 cherry shrimp added together on day one. Change the shrimp’s add-day and run it again to see how much survival changes.
Run this tank yourselfThe numbers in this guide come from the Water Kiwoogi simulator model; real tanks can differ.