How to Cycle a Shrimp Tank: The Complete Beginner's Guide
Updated February 2026 | 10 min read
Cycling a tank is the single most important thing you'll do before adding shrimp. Skip this step, and your shrimp will die. It's that simple.
The good news? It's not complicated once you understand what's happening. This guide will walk you through everything you need to know about cycling a shrimp tank, from the nitrogen cycle basics to fishless cycling methods.
What Is Tank Cycling?
Tank cycling is the process of establishing beneficial bacteria colonies that convert toxic ammonia into less harmful compounds. Without these bacteria, ammonia from shrimp waste builds up and kills your shrimp within days.
Here's how the nitrogen cycle works:
- Ammonia (NH3) - Produced by waste, uneaten food, and decaying plants. Highly toxic to shrimp.
- Nitrite (NO2) - Bacteria convert ammonia to nitrite. Still toxic, but less so.
- Nitrate (NO3) - Different bacteria convert nitrite to nitrate. Much less toxic; removed by water changes and plants.
The goal of cycling is to grow enough bacteria to handle this conversion instantly, keeping ammonia and nitrite at zero.
Why Shrimp Need a Fully Cycled Tank
Shrimp are far more sensitive to water quality than most fish. While a fish might survive a small ammonia spike, shrimp often don't get that chance.
"Shrimp are the canary in the coal mine. They're the first to show stress and the first to die if something's off." - r/shrimptank
Here's what happens to shrimp in an uncycled tank:
- 0.25 ppm ammonia - Shrimp become stressed, stop eating
- 0.5 ppm ammonia - Lethargy, hiding, possible deaths
- 1.0+ ppm ammonia - Mass die-off within 24-48 hours
The same applies to nitrite. Both must read zero before adding shrimp.
The Fishless Cycling Method (Recommended)
Fishless cycling is the best approach for shrimp tanks. You'll add an ammonia source without any livestock, letting bacteria establish before shrimp arrive.
What You'll Need
- API Freshwater Master Test Kit - Essential for tracking the cycle
- Ammonia source (pure ammonia, fish food, or shrimp food)
- Patience (4-8 weeks typically)
Step-by-Step Process
Week 1: Setup
- Set up your tank with substrate, filter, heater, and plants
- Fill with dechlorinated water
- Add your ammonia source to reach 2-4 ppm ammonia
- Test and record ammonia levels
Week 2-3: Ammonia Phase
Your ammonia will stay high while bacteria colonies establish. This is normal. Keep:
- Temperature at 76-80°F (bacteria grow faster in warmth)
- Filter running 24/7
- Light on 8-10 hours for plant growth
Test every 2-3 days. You're waiting for ammonia to start dropping.
Week 3-4: Nitrite Spike
Once you see nitrite appear, congratulations! Your first bacteria colony is working. Ammonia will drop while nitrite rises.
This is the dangerous middle phase. Nitrite often spikes to 5+ ppm. Don't panic; this is normal.
Week 5-6: Nitrite Drop
Nitrite-eating bacteria take longer to establish but eventually catch up. You'll see:
- Nitrite dropping
- Nitrate appearing (this is good!)
- Ammonia staying low
Week 6-8: Cycle Complete
Your tank is cycled when:
- Ammonia drops from 2 ppm to 0 ppm within 24 hours
- Nitrite drops from 2 ppm to 0 ppm within 24 hours
- Nitrate is present (usually 10-40 ppm)
Do a large water change (50-80%) to reduce nitrates before adding shrimp.
Speeding Up the Cycle
Want to cut your cycling time in half? Here's how:
1. Use Established Filter Media
The fastest method. If you know someone with a healthy tank, ask for:
- A used sponge filter
- Some filter floss or ceramic rings
- Substrate from their tank
"I got some filter media from my LFS and my tank cycled in 10 days." - r/shrimptank
2. Bottled Bacteria
Products like Fritz Turbo Start 700 or Seachem Stability contain live bacteria.
Results vary. Some people see great results; others notice little difference. Worth trying if you're impatient.
3. Add Live Plants
Plants help in two ways:
- They absorb ammonia and nitrate directly
- They provide surface area for bacteria
Heavily planted tanks sometimes cycle faster and more stably.
Common Cycling Mistakes
Adding Shrimp Too Early
The #1 cause of shrimp deaths. Even if ammonia and nitrite read zero, wait another week to be sure the cycle is stable.
"I was impatient and added shrimp after 2 weeks because parameters looked good. Lost them all to an ammonia spike 3 days later." - r/shrimptank
Using Chlorinated Water
Chlorine and chloramine in tap water kill beneficial bacteria. Always use a dechlorinator like Seachem Prime.
Cleaning the Filter During Cycling
Your filter houses most of your bacteria. Cleaning it restarts your cycle. Leave it alone until cycling is complete.
Not Testing Regularly
You can't see ammonia or nitrite. The only way to know your cycle progress is testing. Test at least twice a week.
Over-Feeding the Cycle
Adding too much ammonia (over 4 ppm) can stall the cycle. Bacteria get overwhelmed and die off. Keep ammonia at 2-4 ppm.
Testing Your Water
A reliable test kit is non-negotiable. The API Freshwater Master Test Kit tests:
- Ammonia
- Nitrite
- Nitrate
- pH
Liquid tests are more accurate than strips. Yes, they're more work, but they're worth it for shrimp.
Reading Your Results
| Ammonia | Nitrite | Nitrate | Status |
|---|---|---|---|
| High | 0 | 0 | Just started cycling |
| High | Low | 0 | Cycle beginning |
| Dropping | High | Low | Middle of cycle |
| 0 | High | Rising | Almost there |
| 0 | 0 | Present | Cycled! |
The Silent Cycle Method (For Planted Tanks)
If you're setting up a heavily planted tank, you might be able to skip traditional cycling entirely.
How it works:
- Plant heavily from day one (50%+ coverage)
- Add no livestock
- Let plants establish for 4-6 weeks
- Plants absorb ammonia before it becomes a problem
- Bacteria still establish, just more gradually
This works best with:
- Fast-growing plants (hornwort, water sprite, floaters)
- Nutrient-rich substrate
- Good lighting
"My Walstad-style tank with tons of plants never showed ammonia or nitrite. Plants handled everything." - r/shrimptank
When to Add Shrimp
Your tank is ready for shrimp when:
- Ammonia = 0 ppm (for 1 week)
- Nitrite = 0 ppm (for 1 week)
- Nitrate < 20 ppm (do water changes if higher)
- pH is stable (not swinging day to day)
- Temperature is stable (74-78°F for Neocaridina)
Start with 5-10 shrimp, not 50. Watch them for a week before adding more.
Maintaining Your Cycle
Once cycled, your tank stays cycled as long as you:
- Keep the filter running (never turn it off)
- Don't over-clean (rinse filter media in old tank water only)
- Don't overfeed
- Do regular water changes (10-20% weekly)
If you remove all livestock, the bacteria will slowly die off without an ammonia source. Add a pinch of food every few days to keep them fed.
Quick Reference: Cycling Timeline
| Week | What's Happening | Your Job |
|---|---|---|
| 1 | Ammonia high, nothing else | Add ammonia to 2-4 ppm |
| 2-3 | Ammonia still high | Test, wait |
| 3-4 | Nitrite appears! | Keep testing |
| 4-5 | Nitrite spikes high | Don't panic |
| 5-6 | Nitrite drops, nitrate rises | Almost there |
| 6-8 | Both hit zero quickly | Do big water change, add shrimp! |
Final Thoughts
Cycling takes patience, but it's the foundation of a healthy shrimp tank. Rush it, and you'll be replacing dead shrimp. Do it right, and you'll have a thriving colony for years.
The wait is worth it. Your future shrimp will thank you.