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API

API QUICK START Freshwater and Saltwater Aquarium Nitrifying Bacteria 4-Ounce Bottle | Freshwater and Saltwater

  • Based on 15,354 reviews
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Availability: In Stock.
Fulfilled by Amazon
Arrives Tuesday, Aug 25
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Size: 4-Ounce


Features

  • Contains one (1) API QUICK START Freshwater and Saltwater Aquarium Nitrifying Bacteria 4-Ounce Bottle
  • Allows instant addition of fish when starting a new aquarium
  • Reduces compounds harmful to fish when used routinely
  • Helps prevent fish loss in freshwater and saltwater aquariums
  • Use when starting a new aquarium, when adding new fish and when changing water and filter media

Description

In a new aquarium, harmful ammonia and nitrite build up from fish waste, often resulting in fish loss or new tank syndrome. The unique, patented nitrifying bacteria in API quick start are scientifically proven to quickly consume ammonia and nitrite to help prevent new tank syndrome. Allows immediate addition of fish to a new freshwater or saltwater aquarium. Use when starting a new aquarium, adding new fish, changing water, changing filter media, after medicating, or whenever ammonia or nitrite are detected. Allows instant addition of fish. Limits toxic ammonia and nitrite. Helps prevent fish loss. Immediately starts aquarium cycle. Contains live, nitrifying bacteria. No refrigeration required. All natural. Aquarium Nitrifying Bacteria

Brand: API


Liquid Volume: 118 ml


Item Weight: 4.8 ounces


Item Form: Liquid


Number of Packs: 1


Product Dimensions ‏ : ‎ 1.5 x 1.5 x 6 inches; 4.8 ounces


Manufacturer recommended age ‏ : ‎ 1 month and up


Item model number ‏ : ‎ 89C


Department ‏ : ‎ Unisex-Adult


Date First Available ‏ : ‎ January 14, 2012


Manufacturer ‏ : ‎ Mars Fishcare


Best Sellers Rank: #1,486 in Pet Supplies (See Top 100 in Pet Supplies) #4 in Aquarium Water Treatments


#4 in Aquarium Water Treatments:


Customer Reviews: 4.8 4.8 out of 5 stars (15,354)


Brand Name: API


Number of Packs: 1


Unit Count: 4 Fluid Ounces


Manufacturer: Mars Fishcare


UPC: 317163030899


Number of Items: 1


Global Trade Identification Number: 99


Item Type Name: Aquarium Bacteria


Model Number: 89C


Manufacturer Part Number: 89C


Liquid Volume: 118 ml


Item Weight: 4.8 ounces


Item Form: Liquid


Pet Type: Fish


Target Species: Fish


Allergen Information: Apple Free


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Aug 25

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

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View our full returns policy here.

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Similar Products

Top Amazon Reviews

    • Seemlessly cycled tank
Size: 4-Ounce
My old aquarium started leaking at the sides so I had to replace it in a hurry. Besides using the same filter media in the new tank that was used in the old tank, I started from scratch with everything else in the tank. I bought this Quickstart product in hopes I can avoid going through the long cycling process that's hard on fish. After filling the new tank I added the amount stated on the bottle, and adding a smaller amount with each weekly water change. It's been about a month and my new aquarium has remained crystal clear the entire time without any signs of bacterial bloom or cloudiness, I've also been using water test strips and so far the water quality has remained good. While I'm sure using previously used filter media helped, there have been times before when I've upgraded to new tanks and the water still would become cloudy even with a previously used filter so I feel like this product definitely made a difference. I originally purchased it to help with the initial cycling but now I plan to continue using it when doing larger water changes or when replacing the filter media. ... show more
Reviewed in the United States on May 17, 2026 by Sara
    • Seems fine
Size: 16-Ounce
Doesnt stink, haven’t seen any issues. More concentrated than past brands.
Reviewed in the United States on August 3, 2026 by John Doe
    • A Must‑Have for Safe, Fast, and Stress‑Free Tank Cycling
Size: 4-Ounce
Works fast, keeps ammonia and nitrite in check, and makes new tank setups stress‑free. Great for both freshwater and saltwater. Highly recommend.
Reviewed in the United States on June 5, 2026 by Wayne
    • Good deal.
Size: 32-Ounce
Gives confidence for fish health
Reviewed in the United States on June 15, 2026 by K. Franzese
    • Good to have!
Size: 32-Ounce
I just buy all API products, I chose this size because I have a 75gallon size tank, so my products need to last for awhile.
Reviewed in the United States on May 11, 2026 by Meka
    • Instant Cycle Saver – API QUICK START is a Must-Have for Any Aquarium!
Size: 16-Ounce
The API QUICK START for freshwater and saltwater aquariums is a total game-changer—especially if you're setting up a new tank or adding fish to an existing one. It makes the nitrogen cycle process way less stressful, both for you and your fish. I used it when starting a new freshwater setup, and within 24 hours my tank was safe and stable. No ammonia spikes, no nitrite issues—it genuinely helps establish the biological filter FAST. It's also great to use after water changes, adding new fish, or cleaning the filter. What I love is that it’s super easy to use—just shake and pour. The bottle gives clear instructions, and the results speak for themselves. My fish were active and healthy from day one. This is one of those products you always want on hand. It helps create a healthy environment and gives peace of mind whether you're a beginner or a seasoned aquarist. ... show more
Reviewed in the United States on July 21, 2025 by Giovanni Santa Ana
    • only put this stuff in when your tank is filthy
Size: 4-Ounce
its awesome for fish tanks and it lights up my aquarium with beautiful clear water
Reviewed in the United States on May 21, 2026 by Caleb W. Kimbrough
    • Fixed my cyanobacteria issue!
Size: 16-Ounce
Last year I made the conversion to planted tanks and ever since then, I have been battling cyanobacteria in my 75 gallon tank. Ammonia, nitrites, and nitrates were always great, but within 1-2 days of an extremely thorough tank maintenance session (1-2 hours of cleaning plants, wood, walls, rocks + water change), the cyanobacteria population would explode. If I didn't address it right away, the plants, substrate, walls, heater, and filter would be covered in sheets of cyanobacteria. Take maintenance every 1-2 days was not very sustainable. I tried feeding less, feeding flakes vs crisps vs round pellets. Some types of food exacerbated the issue. Pellets and the premium gel food helped combat the growth of cyanobacteria but I still had to do tank maintenance every 3-4 days. I tried completely resetting the tank using the existing plants (cleaned) and swapping wood for rocks. I tried adding $300 worth of plants, in addition to what was already planted. I tried moving plants and decor around for optimal water flow so there weren't any dead spots. I tried moving from a canister filter to an external filter. Then I upgraded to a higher capacity external filter to get better water flow in the tank. I tried treating the tank with different products, specifically formulated to address the cyanobacteria and although it would keep it at bay, once you stopped using the product, the cyanobacteria would be back in full force. All of this was expensive and futile because the cyanobacteria always returned with a vengeance. Of course, no one could give me a definitive answer to the cyanobacteria problem. I scoured article after article, frustrated that I couldn't find a solution that actually worked. And believe me, I spent $1000+ over the year trying a number of different solutions; none of them worked permanently. I was seriously rethinking my fish hobby when I stumbled across the solution. I picked up Quick Start for another tank that I wanted to rebuild. I happened to be doing a water change for my 75 gallon tank at the same time and I accidentally put Quick Start in my 75 gallon tank. No biggie, I thought. Wouldn't hurt and I didn't want to waste the water. In two days, I noticed that the cyanobacteria's growth had been stunted. It was growing about half the speed it normally did. The next water change, I used Quick Start again. I didn't understand - my levels were good when I tested them so I didn't think my bacteria levels were low and I never thought to use Quick Start as a result. Over the next few weeks, I kept using Quick Start in my water changes, I got a bunch of snails (freeloaders from my plant purchases), and I stopped vacuuming the substrate so thoroughly and now the cyanobacteria is 95-98% gone. I only occasionally see it on the walls and I can push my water changes to every two weeks, no problem. I think I owe my sanity to Quick Start. ... show more
Reviewed in the United States on July 8, 2023 by ★AM1 Engineer★

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