Search  for anything...

Seachem Stability Fish Tank Stabilizer - For Freshwater and Marine Aquariums, 16.9 Fl Oz (Pack of 1)

  • Based on 12,362 reviews
Condition: New
Checking for the best price...
$14.25 Why this price?
Save $2.43 was $16.68

Buy Now, Pay Later


As low as $3 / mo
  • – 4-month term
  • – No impact on credit
  • – Instant approval decision
  • – Secure and straightforward checkout

Ready to go? Add this product to your cart and select a plan during checkout.

Payment plans are offered through our trusted finance partners Klarna, PayTomorrow, Affirm, Afterpay, Apple Pay, and PayPal. No-credit-needed leasing options through Acima may also be available at checkout.

Learn more about financing & leasing here.

Selected Option

Free shipping on this product

30-day refund/replacement

To qualify for a full refund, items must be returned in their original, unused condition. If an item is returned in a used, damaged, or materially different state, you may be granted a partial refund.

To initiate a return, please visit our Returns Center.

View our full returns policy here.


Availability: In Stock.
Fulfilled by Amazon

Arrives Thursday, Oct 2
Order within 10 hours and 29 minutes
Available payment plans shown during checkout

Size: 500 ml


Color: clear


Features

  • TANK STABILIZATION: Seachem Stability will rapidly and safely establish the aquarium biofilter in freshwater and marine systems, thereby preventing the #1 cause of fish death: "new tank syndrome".
  • TREATMENT: Stability is formulated specifically for the aquarium and contains a synergistic blend of aerobic, anaerobic, and facultative bacteria which facilitate the breakdown of waste organics, ammonia, nitrite, and nitrate.
  • BACTERIA GROWTH: The necessary conditions for the growth of Stability's bacteria strains encompass a very broad range. When other bacteria begin to die off (usually from high organic loads caused by the unknown death of an organism), Stability simply becomes more effective.
  • USE: Shake Seachem Stability well before use and turn off UV/ozone filter. Use 1 capful (5 mL) for each 40 L (10 US gallons) on the first day with a new aquarium. Then use 1 capful for each 80 L (20 US gallons) daily for 7 days. Fish and other aquatic species may be introduced at any time as long as dosage is maintained for 7 days.
  • SAFE: The bacteria employed by Stability are non-sulfur fixing and will not produce toxic hydrogen sulfide. Stability is completely harmless to all aquatic organisms as well as aquatic plants, thus there is no danger of overuse.

Description

Seachem Stability will rapidly and safely establish the aquarium biofilter in freshwater and marine systems, thereby preventing the 1 cause of fish death: "new tank syndrome". For over three decades, Seachem has been a company rooted in sound science. Our experience in the hobby and an educated staff of chemists and biologists are part of the package when you purchase Seachem products. Seachem remains as one of the few surviving independent and privately owned pet care companies. Seachem is owned and operated by hobbyists. All of our employees are hobbyists who maintain aquariums at home and at the office. Seachem itself was started because one such passionate hobbyist - Dr. Leo G. Morin (Founder) - recognized that the available solutions to aquarists problem wanting. This resulted in Seachem’s very first product: Cupraplex (today known as Cupramine). Over thirty years later Seachem is still approaching old problems in a new way. Seachem’s philosophy is that the knowledgeable hobbyist makes the best customer. This is reflected in solid and reliable customer education and support as well as products proven in science and performance. While Seachem has grown rapidly into a national and international firm, it retains the culture of a small company and is readily available to its customers.

Brand: Seachem


Liquid Volume: 5E+2 Milliliters


Item Weight: 1.09 Pounds


Item Form: Liquid


Target Species: Fish


Is Discontinued By Manufacturer ‏ : ‎ No


Product Dimensions ‏ : ‎ 7.6 x 2 x 1.5 inches; 1.09 Pounds


Item model number ‏ : ‎ 123


Date First Available ‏ : ‎ June 20, 2004


Manufacturer ‏ : ‎ Seachem Laboratories, Inc.


Best Sellers Rank: #1,965 in Pet Supplies (See Top 100 in Pet Supplies) #6 in Aquarium Water Treatments


#6 in Aquarium Water Treatments:


Customer Reviews: 4.8 4.8 out of 5 stars 12,362 ratings


Item Weight: 1.09 pounds


Manufacturer: Seachem Laboratories, Inc.


Item model number: 123


Date First Available: June 20, 2004


Item Package Dimensions L x W x H: 7.48 x 2.5 x 2.4 inches


Item Dimensions LxWxH: 7.6 x 2 x 1.5 inches


Item Weight: 1.09 Pounds


Brand Name: Seachem


Target Audience Keyword: all fish, fish


Country of Origin: United States


Model Name: Stability 500ml


Color: clear


Size: 500 ml


Material: Rubber


Age Range Description: All Life Stages


Number of Items: 1


Style: Tank Stabilizer


Included Components: Aquatics, Maintenance and Supplies, Aquarium-Biological-Additives


Specific Uses for Product: Active


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Thursday, Oct 2

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

  • Klarna Financing
  • Affirm Pay in 4
  • Affirm Financing
  • Afterpay Financing
  • PayTomorrow Financing
  • Financing through Apple Pay
Leasing options through Acima may also be available during checkout.

Learn more about financing & leasing here.

Top Amazon Reviews


  • Best for cycling!
Size: 500 ml Color: clear
Best product I've ever used to cycle a tank quickly! Highly recommend!
Reviewed in the United States on July 20, 2025 by Scarecrow2021

  • It keeps my nitrite in range.
Size: 2 L/ 67.6 fl. oz. Color: No Color
It works exclent keeping my aquarium in exclent shape.
Reviewed in the United States on July 21, 2025 by Patrick H. Van Cleave

  • Happy
Size: 500 ml Color: clear
Works as described. Happy with the purchase.
Reviewed in the United States on July 28, 2025 by Metroman

  • This product worked for me
Size: 500 ml Color: clear
Stability helped me start and establish a brand new 55G tall from scratch with only one fish departing to the Golden Pond in the Sky (loach swam up the intake into the filter impeller...messy). From day one I did daily testing with the API kit and made an Excel spreadsheet of the data. There were very small, irregular ammonia spikes at the 2nd/3rd week, but not into the "danger" zone and slowly decreased to 0ppm by the end of the 4th week. Nitrites and nitrates increased from the 3rd week and then hovered at a "very acceptable" range below danger zone and then gradually decreased to ~0 ppm for nitrites and ~20ppm for nitrates by the 5th/6th week. The results I got from the test kit were evaluated against a U of Florida's chart (I am a bio major) of Total Ammonia Nitrogen Toxicity (using pH and water temperature as the other parameters), and were in the range that is deemed not dangerous to FW fish for a short term period. With the results of these API test and my personal experience, I would definitely recommend and have been using Seachem Stability as a "jump start" product to establish the important biological filter in a FW aquarium or to boost or supplement the already existing bio filter in an established tank. For those interested about my experience, see below for in depth details. Products used: -Seachem Stability -Seachem Prime -API FW Master Test Kit 1st week: IMPORTANT: FOLLOW THE DIRECTIONS FOR THE FIRST WEEK'S DOSING SCHEDULE BASED ON YOUR TANK'S VOLUME. Added 7 Zebra danios. These are hardy fish and can survive a newbie's foray into fishkeeping and hopefully any mistakes I make. First day: One capful( 5mL) for every 10G of NEW WATER, so 5 capfuls. Days 2-7: One capful for every 20G of water, so ~3 capfuls EVERYDAY. Added 4 black Java loaches/khuli loaches on day 3. Note: Directions says you can add fish/inverts immediately and at any time as long as you follow the all-important dosing schedule above for the FIRST week only. NOTE: After first week, one capful for every 20G once a month, or with each water change, or introducing new fish, or medicating. 2nd week: Added Dwarf gourami and 3 Albino cories. Did 25% water change with Prime, then dosed with 3 capful of Stability, which is the dose for ~60G. 3rd week: Added Bristlenose pleco. Did 25% WC with Prime, then dosed with 3 capful of Stability. 4th week: Added 3 more Albino cories. Added 1teaspoon/10G API Aquarium salt to counter increasing ammonia, nitrites and nitrate spikes. 5th week: Added 5 more loaches. Did 25% WC with Prime, then dosed with 3 capful of Stability. 6th week: Added 2 Amano shrimps. Did 25% WC with Prime, then dosed with 3 capful of Stability. 4 months later: 3 Bamboo shrimps, 2 Amano shrimps, 9 Loaches, 6 Cories, Dwarf gourami, 7 Danios, BN pleco, plants. All fish/inverts growing and healthy. I now only dose 1 capful of Stability with each 25% WC, as my biofilter is now well established and API tests show it doesn't need 3 capfuls for every WC. Thanks Stability! ... show more
Reviewed in the United States on September 19, 2013 by Johnny

  • Great item
Size: 500 ml Color: clear
Why did you pick this product vs others?: Does what it’s suppose to
Reviewed in the United States on July 8, 2025 by Adrian Garcia

  • Excelente
Size: 500 ml Color: clear
Excelente
Reviewed in the United States on June 5, 2025 by Felix Diaz

  • Seachem makes the best beneficial bacteria in a bottle
Size: 2 L/ 67.6 fl. oz. Color: No Color
I use seachem products on all of my aquariums, this is the best value for your money when it comes to water, cleanliness and water clarity. The size of this product helps with large aquariums and the smell is not that bad.
Reviewed in the United States on May 31, 2025 by Kelly Bunch

  • Greatly speeds up the cycle
Size: 500 ml Color: clear
I used Stability to kickstart the cycle on a new tank and it worked faster than I expected. I dosed it daily for the first week like the bottle says, and by day 5 or 6 ammonia and nitrites were already dropping. I was also using bottled ammonia and keeping things consistent, but I do think this made a big difference. Water stayed clear the whole time and there was no weird smell or cloudiness. I’ve used a few other bacteria starters before and this one seems to actually do something right away. Might not be “instant” like some people say, but it definitely sped things up. I’d use it again for sure. ... show more
Reviewed in the United States on June 8, 2025 by Ray C.

Can't find a product?

Find it on Amazon first, then paste the link below.
Checking for best price...