Fritz Zyme 9 Saltwater Nitrifying Bacteria for Aquariums, 8-fl oz bottle

Deal
Skip image gallery
Slide 1 of 2

$4.67 First Time Autoship Price
this order
Save 35% (up to $20) today when you set up Autoship. 
$7.19 Autoship Price
future orders
  • Get deliveries on your schedule
  • Skip, change, or cancel anytime
$7.19 Chewy Price
($0.90 /fl oz)
Save $1.80 (-20%)
$8.99 List Price
Promo, New Customers Only: Spend $49+, Get $20 eGift Card + Free Shipping with code: WELCOME
In Stock
FREE 1-3 day delivery on first-time orders over $35
Free 365-day returns

No interest if paid in full in 6 months on PayPal purchases of $149+. .

About This Item

Details

  • Formulated to immediately work to remove ammonia and nitrite with fast-acting nitrifying bacteria.
  • Made for saltwater tanks and reduces cycle time so you can add fish without having to wait.
  • The natural bacteria “move in” to your biofilters to establish colonies to keep your tank healthy, and won’t harm invertebrates.
  • Prevents new tank syndrome and can be used in established tanks, after water changes, adding medications or introducing new fish.
  • Available in 8-oz, 16-oz and 32-oz bottles to suit your needs and aquarium size.

Instructions

Frequently bought together

Questions & Answers

1 Customer Questions

How many gallons does the 32 oz do?

Answer by Chewy • Jan 24, 2022
For a new system, dose 4 ounces per 5 gallons. For a large livestock system, new system dosage may be safely increased up to 10x. For established systems, use 2 ounces per 5 gallons.
Reviews
Write a Review
4.6
Rated 4.6 out of 5 stars
25 Ratings
Terms & Conditions

10 Customer Reviews

Rated 5 out of 5 stars
By Kylina on Oct 22, 2025

just what i needed !

great price and great product

great price and great product

Rated 5 out of 5 stars
By Todd on May 3, 2025

Cycled tank fast

Tank cycled less than two weeks. I’ve used other brands in the past to cycle tanks this by far was the fastest.

Tank cycled less than two weeks. I’ve used other brands in the past to cycle tanks this by far was the fastest.

Rated 4 out of 5 stars
By Tom on Jun 14, 2025

Nitrifying Bacteria

It’s doing the unglamorous but necessary work it needs to do!!

It’s doing the unglamorous but necessary work it needs to do!!

Rated 5 out of 5 stars
By Robin on Aug 4, 2024

Excellent for adding fish to a new tank, safely!!

I love this product!! It is so good for fish! No heavy breathing nor stressing if you follow directions as it is.

I love this product!! It is so good for fish! No heavy breathing nor stressing if you follow directions as it is.

Rated 3 out of 5 stars
By Eugene on Aug 3, 2024

1st reef

this was so helpful

this was so helpful

Rated 5 out of 5 stars
By Edward on Jan 6, 2024

Great Price

Notice Chewy is much cheaper than Amazon

Notice Chewy is much cheaper than Amazon

Rated 5 out of 5 stars
By Dakevbo on May 7, 2023

You Must Wait to Add Fish

Like all bacterial additives, you need an ammonia source. If you add fish to provide this source you are stressing your fish. Add pure ammonia or a piece of raw

Like all bacterial additives, you need an ammonia source. If you add fish to provide this source you are stressing your fish. Add pure ammonia or a piece of raw shrimp and then add Fritz 9. You will need to measure your ammonia and nitrite. Once they go down and you see a nitrate spike you can do a small water change and then add fish. This cycle takes at least a week. Fritz 9 only gives the nitrogen cycle a jump start.

Rated 5 out of 5 stars
By jbhydroman on Jun 4, 2023

Great Stuff

Great bacteria for the Saltwater Hobbyist. Will tackle Ammonia spikes. The product has a long shelf life.

Great bacteria for the Saltwater Hobbyist. Will tackle Ammonia spikes. The product has a long shelf life.

Rated 1 out of 5 stars
By Charles on Nov 30, 2022

Do Not Add Fish Immediately

Directions State - Allows Safe Immediate Introduction of Livestock. I Added Fritz Zyme to a new aquarium fallowing directions. After 2 hours ammonia and nitrite

Directions State - Allows Safe Immediate Introduction of Livestock. I Added Fritz Zyme to a new aquarium fallowing directions. After 2 hours ammonia and nitrite were still to high to add fish. This possibly due to Fedex delivering a day late and allowing the bottle to freeze.

Rated 4 out of 5 stars
By Maee on Jan 31, 2022

It works well

It clears the bacteria but you have to use it every 5 days or so

It clears the bacteria but you have to use it every 5 days or so