FritzZyme® 9 Saltwater

  • The Original Live Nitrifying Bacteria

  • No Need for Refrigeration and One Year Shelf Life

  • Rapidly Eliminates Toxic Ammonia and Nitrite

  • FritzZyme® 7 is Good for Fresh and Brackish Systems

  • Great for Use After Maintenance

About FritzZyme® 9 Saltwater

FritzZyme® 9 contains live saltwater-specific strains of live nitrifying bacteria proven to reduce fish loss due to toxic levels of ammonia and nitrite. Nitrifying bacteria can take weeks to naturally establish colonies in new aquariums while ammonia and nitrite can reach lethal levels in only a few days. FritzZyme® 9 provides the proper balance of bacteria proven to rapidly seed biofilters, greatly reducing the natural cycle time allowing for safe, faster addition of livestock.

FritzZyme® 9 may be added to new tanks or established systems any time the biofilter needs fortification including: after water changes, aggressive cleaning, adding new livestock, medicating or changing filter media.

Why add nitrifying bacteria?

Nitrifying bacteria can take weeks to naturally establish colonies in new aquariums while ammonia and nitrite can reach lethal levels in only a few days. FritzZyme® Live Nitrifying Bacteria provides the species of bacteria proven by professional zoos, aquariums, universities, and aquaculture facilities to rapidly seed biofilters. FritzZyme® quickly removes toxic ammonia and nitrite in existing systems and greatly reduces cycle time allowing for safe, immediate addition of livestock in new systems. FritzZyme* Nitrifying bacteria may also be added any time the bio-filter needs fortification including after water changes, aggressive cleaning, adding new livestock, medicating, or changing filter media.

Live, Viable Product

Unlike some heterotrophic bacteria, which can survive in a long-term spore state, only true nitrifying bacteria can cycle an aquarium. True nitrifying bacteria are fragile and temperature-sensitive, which is difficult to produce and package. FritzZyme® 9 is buffered for long-term stability without the need for refrigeration.

Years of Proven Success

Fritz Aquatics has been continuously producing the highest quality, viable, nitrifying bacteria for over 30 years and was the first company to commercially produce nitrifying bacteria for the aquarium industry. Fritz Aquatics has remained a leader in the industry with continuous research, production, and development. There are very few producers of true live nitrifying bacteria, none of which can match the experience and success of FritzZyme®. 

Need help? Try our FritzZyme user guide!

Directions & Dosage

For a new system, dose 4 oz (119 ml / ½ cup) per 5 US gallons (19 L). For established systems, use 2 oz (60 ml / ¼ cup) per 5 US gallons (19 L). For a large livestock system or systems with heavy bioload, new system dosage may be safely increased up to 10x.

Need help? Try our FritzZyme user guide!

  • For best results, maintain ideal water parameters noted below and use FritzZyme® 9 before the expiration date on the package
  • Nitrifying bacteria require ammonia and nitrite to survive; in new systems introduce livestock or another ammonia source like Fishless Fuel to start cycling
  • Maintain adequate water flow or aeration
  • Discontinue use of skimmer and UV sterilizers for at least 5 days after application
  • No contraindications: can be used with all of our other products and meds
  • Safe for use with all species, including plants and invertebrates
  • Safe to add directly into a tank with livestock present
  • Will not color or cloud aquarium water
  • Variations of odor and color between bottles is normal, a strong sulfur smell does not indicate the bacteria are dead
  • Do not freeze or overheat. Store in a cool, dark place
  • Overdosed? Live nitrifying bacteria are very safe even if overdosed. Observe for any distress, perform small water changes if necessary

Ideal parameters for FritzZyme® 9 nitrifying bacteria:
Temperature: 77 - 86 F (25 - 30 C)
pH: 7.3 - 8.0
Salinity: 15 - 40 ppt (1.011 to 1.030 sg)
Alkalinity (KH): minimum 4.5 dKH or 80.5 ppm KH
Phosphate: above 0 ppm


Size Treats Item Number
8 oz / 237 mL 20 gal / 76 L 80203
16 oz / 473 mL 40 gal / 151 L 80204
32 oz / 946 mL 80 gal / 303 L 80205
1 gal / 3.78 L 320 gal / 1,211 L 80206



See below for frequently asked questions regarding FritzZyme® 9 Saltwater.

  • How often should I use FritzZyme® Nitrifying Bacteria?

    After the initial dosage of FritzZyme® to seed the biofilter, additions are only needed if more animals are added to the system, the efficiency of the biofilter has been reduced by medications or the biofilter has been disturbed (e.g., changing the media of a canister filter).

  • Why does it take so long for an aquarium to cycle without FritzZyme® Nitrifying Bacteria?

    In comparison to other types of bacteria, nitrifying bacteria grow very slowly. Under optimal conditions, it takes fully 15 hours for a colony to double in size! By adding FritzZyme® nitrifying bacteria, you are adding bacteria to your system in amounts that would have taken weeks to naturally grow.

  • What if my nitrites will not go down in my freshwater aquarium treated with FritzZyme® Nitrifying Bacteria?

    In freshwater, we occasionally run across this situation, and the first thing we recommend is testing your alkalinity. In aquariums with an alkalinity below a 4.5 dKH (1.6 Meq/l), the bacteria that convert the nitrite to nitrate simply stop the conversion process. We have found that after raising alkalinity to a minimum of 4.5 dKH (1.6 Meq/l) but ideally 5.6 dKH (2.0 Meq/l), nitrite conversion proceeds rapidly. In very, very rare cases the nitrite portion of the cycle remains stalled. In that situation, check your phosphate levels. Nitrifying bacteria, like all living organisms, need trace amounts of phosphate to function. A fishless cycle using ammonium chloride and RO/DI water may have 0.00ppm phosphates and will not complete the cycle. Even a trace amount of phosphate will allow the nitrifying bacteria to rapidly convert nitrite to nitrate. Fish food is a source of phosphate and Fritz pH Neutralizer contains phosphates. ⅛ to ¼ the standard dose would provide enough phosphate for nitrite conversion.

  • How long has Fritz Industries, Inc. been working with nitrifying bacteria?

    Fritz Industries, Inc. has been working with nitrifying bacteria for over 26 years and has constantly worked to perfect culturing techniques while obtaining maximum production with superior packaging of a stabilized product.

  • Why not have a dry version of FritzZyme® 7 or 9?

    FritzZyme® contains true nitrifying bacteria. These bacteria have a low survival rate when dried or freeze-dried. Low survival rates mean very few viable “living” nitrifying bacteria would be added to the aquarium. Although competitors claim to have dry versions, tests have shown that these products actually do not establish the biofilter significantly faster than the biofilter would have established on its own.

  • How does FritzZyme® Nitrifying Bacteria compare to other products?

    FritzZyme® was the first product on the market to rapidly establish biological filters in aquatic systems. Having been on the market for over 15 years, it is the only time-proven product of its kind, becoming known as “the bacteria that works.” Since over 75% of the ammonia generated within the aquarium comes from direct excretion from the fish, it only makes sense to use bacterial products which provide the nitrifying bacteria to utilize this ammonia. If the product will not utilize ammonium chloride, it will not utilize the excreted ammonia. Therefore, although other products have been introduced on the market with many claims, be assured there is only one tested, proven FritzZyme®.

    In addition to FritzZyme® being sold throughout the pet industry, the Fritz Pet division supplies FritzZyme® to professional fish, shrimp and lobster farms, city aquariums, universities, research facilities and zoos throughout the world. Many entertainment parks are also regular users of FritzZyme®. To these professionals, having a reliable product to establish and maintain their systems is of vital importance. They rely on FritzZyme®.

  • What is the difference between FritzZyme® 7 and FritzZyme® 9?

    FritzZyme® 7 is for freshwater use and FritzZyme® 9 is for brackish and saltwater use. Both FritzZyme® 7 and 9 work the same natural way, but the species of bacteria differ in order to achieve the best results possible in each environment. By having separate products with optimum species for each environment, the “lag time” for the bacteria to adjust is avoided. If the wrong FritzZyme® is used, you will not achieve the needed ammonia and/or nitrite control. Introduce the correct FritzZyme® as soon as possible. Water changes to remove the incorrect FritzZyme® will not be necessary.

  • How does FritzZyme® Nitrifying Bacteria work?

    FritzZyme® allows your tank to duplicate nature. FritzZyme® “seeds” the biological filter with sufficient numbers of beneficial nitrifying bacteria so it can begin to remove ammonia and nitrite. Because the time required for the bacteria to become established is drastically reduced, fish may be introduced much sooner. When adding more fish or other bio-load to an aquarium, the addition of FritzZyme® adds more bacteria to the biofilter, thus preparing it to be able to handle the increased ammonia production.

  • What products should not be used with FritzZyme®?

    U.V. sterilizers, foam fractionators (protein skimmers) and ozone generators should not be used for at least 5 days after FritzZyme® additions. This allows the bacteria time to become attached so that they will not be killed or removed by these types of equipment. Many medications will also reduce the efficiency of the biofilter.

  • Do I need to add an initial ammonia source for the nitrifying bacteria of a new tank?

    Your fish will provide the necessary ammonia. The advantage of using FritzZyme® is that you can add the fish right away to a new tank (without adding any ammonia); this is the method we recommend. Slight rises in ammonia and nitrite may occur for a brief period, but they will be well below stress levels.

  • How can I tell if the FritzZyme® Nitrifying Bacteria has spoiled?

    Short of being exposed to freezing or very high temperatures, a sealed bottle of FritzZyme® should be viable up to its expiration date. If there is no conversion of ammonia and nitrite, there is a very slight possibility that the bacteria has died (due to freezing or overheating). More likely, other inhibitory factors may be affecting the bacteria (see above). Alive or dead, FritzZyme® is non-toxic and completely safe. It will not harm fish or invertebrates, even if accidentally overdosed.

  • Can I use copper medications with FritzZyme® in my marine aquarium?

    The use of any medications in either fresh or saltwater aquariums should be avoided until the biofilter has become well-established. Any medications or water conditioners containing copper, formaldehyde, malachite green and methylene blue are extremely inhibitory or lethal to nitrifying bacteria. Occasional outbreaks of protozoan parasites during this period are usually due to ammonia-related stress. Treating with one of these chemicals only adds to the problem by allowing ammonia to reach toxic levels. It is advisable to remove infected fish to a quarantine or hospital tank for treatment. Once nitrifying bacteria have become well established, they will become tolerant to low levels of copper.

  • Can I use chemical ammonia removers with FritzZyme® Nitrifying Bacteria?

    Chemical ammonia removers work by converting poisonous ammonia to non-toxic compounds. Nitrifying bacteria may not be able to utilize some of these compounds. The use of ammonia removers will only prolong the time needed to establish the biofilter. Repeated use of these chemicals may also lower the pH of the water. Nitrification will cease if the pH drops below 6.5.

  • What levels of ammonia and nitrite should I see when using FritzZyme® Nitrifying Bacteria?

    You will see the normal “new tank syndrome” time greatly reduced or completely eliminated. The ammonia and nitrite levels, if present, will be well below stress levels. Problem systems will recover in a matter of days without extensive water changes.

  • Do you need a weekly dose every week with FritzZyme® Nitrifying Bacteria?

    Normally, it is not necessary for you to put additional dosages of FritzZyme® in your tank once the tank has cycled. Often, aquarium users place additional dosages in their tanks if they are adding new fish, are cleaning their filters or see an occasional ammonia or nitrite spike. If your aquarium is looking great and the ammonia and nitrites are at or near zero, it normally is not necessary to add additional product.

  • Does the color or smell change the effectiveness or remaining shelf life of FritzZyme® Nitrifying Bacteria?

    No. The smell may range from none to a very strong pungent odor and the color from a rosy red to a grayish black. We have seen the odor and color ranges mentioned above to be equally effective. The true test of the product effectiveness is its ability to convert ammonia and/or nitrite. If the product has not expired and has been handled properly, it will be effective in the aquarium.

  • What other products may be used with FritzZyme®?

    Chlorine must be removed before adding FritzZyme® (chlorine kills bacteria). FritzGuard® or Fritz Chlorine Remover may be used for this purpose. Fritz pH blocks for pH control, Fritz Super Salt for marine systems, Fritz Super Clarifier and Fritz Trace Elements may also be used without any adverse effect to the biofilter.

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