The Best Beneficial Bacteria for Aquarium [Reviews and Comparisons] 

Estimated read time 11 min read

Getting bacteria for your aquarium may seem weird, but all seasoned aquarists know that this is essential. The best nitrifying bacteria supplement for a freshwater aquarium will do wonders to keep the water clean.

No matter how well you clean and maintain your aquarium, the plant debris and fish waste will eventually make the water murky. While you can perform full or partial water changes more often than your usual schedule, this requires tons of effort.

If you want to clean your tank in an effective and time-saving manner, getting the best nitrifying bacteria supplement for a freshwater aquarium is something you should do.

Beneficial bacteria will do most of the work to keep your tank clean. This task works by breaking down the debris and dirt from plants and fish, keeping the tank’s water clean and free of toxins. This way, it will be healthier for your fish.

When it comes to aquarium water treatments, there are a variety of products available, each with a specific purpose.

Our Best Aquarium Bacteria Supplement Reviews and Comparisons

While bacteria can grow in aquariums over time, you can use a supplement to get it going earlier. The best nitrifying bacteria supplement will keep the ammonia and nitrate in your aquarium within acceptable levels.

When the level of nitrate or ammonia in a fish tank is high, it can be toxic to your fish.

However, shopping for a nitrifying bacteria supplement can be highly confusing. This is because there are so many products on the market. If you don’t have time to comb through each of our choices, you should pick our favorites: Seachem Stability and Fritz Aquatics.

 1. SeaChem Stability Beneficial Bacteria

Seachem Stability Fish Tank Stabilizer - For Freshwater and Marine Aquariums 500 ml

The SeaChem Stability beneficial bacteria may not look unique compared to other nitrifying bacteria supplements, but it’s a clear standout. It keeps ammonia and nitrate levels in control, especially in new tank setups with new biofilters. This ability will prevent “new tank syndrome,” the most common cause of fish death.

The formula of this product contains a blend of anaerobic, aerobic, and facultative bacteria that allows the fast breakdown of ammonia, nitrite, nitrate, and waste organics to keep the water clear and odorless.

The bacteria used by this product will not produce toxic hydrogen sulfide, so the integrity of your water will remain as it is, including the pH level.

SeaChem Stability also has a formula that is harmless to aquatic species, and you won’t have to worry about putting too much product on your tank. Aside from working well in freshwater aquariums, it can also be used for saltwater aquariums.


  • Great for avoiding new tank syndrome
  • Best used when performing water changes and adding new fish
  • Relatively inexpensive


  • Does not have a water conditioner
  • It does not include ammonia source

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2. SeaChem Prime

Seachem Prime Fresh and Saltwater Conditioner - Chemical Remover and Detoxifier 500 ml

If you’ve been an aquarist for quite some time, you’ve probably heard about this product. The SeaChem Prime is known for its versatility. Its primary function is to get rid of chlorine and chloramine and detoxify heavy metals. This way, all the fish in your tank will be safe.

This product can also eliminate nitrites, ammonia, and nitrates, highly toxic to fish. One of the things users love about this product is it doesn’t change the water parameters, which can cause sickness and stress to your fish.

However, it’s worth noting that this product has a foul odor. After dosing your aquarium in the first 48 hours, you may smell something that resembles a rotten egg. This characteristic can be a deal-breaker for many.

It may also give false ammonia readings in your water testing kit in its first 48 hours. It is also important to mention that this product contains hydrosulfite salts which are dangerous to humans.


  • Maintains the pH level in your aquarium
  • Can detoxify ammonia, nitrites, and nitrates well


  • Smells bad
  • It contains a hazardous ingredient

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3. Fluval Hagen Biological Booster

Fluval Cycle Biological Enhancer, Aquarium Water Treatment, 16.9 Oz., A8351

Another excellent option for saltwater and freshwater aquariums is the Fluval Hagen Biological Booster.

This supplement can help you lessen the risk of fish loss while cycling your aquarium, and it can also be used after water changes, filter changes, or after a cycle crash.

The beneficial bacteria in this product work by eliminating the nitrites and ammonia in your tank. With continued use, this product will help with the growth of bacteria in your aquarium.

The Fluval Hagen Biological Booster needs ammonia in the aquarium to be established. Use this product daily for three days, but make sure you don’t forget to monitor the parameters of your tank.


  • Versatile use for freshwater and saltwater aquariums
  • Reduces fish loss during cycling
  • Reduces toxic waste products


  • Needs ammonia in the tank
  • Long waiting time

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4. Fritz Aquatics FritzZyme 7

Fritz Aquatics 80210 FritzZyme 7 Nitrifying Bacteria for Fresh Water Aquariums, 32-Ounce

Patience is vital when taking care of your new aquarium because it can take weeks to establish it. If you don’t prioritize this, the nitrate and ammonia levels may increase to a dangerous level within the first hours or days.

This problem is what the Fritz Aquatics FritzZyme wants to solve. This product includes different strains of bacteria so you can quickly establish positive bacteria colonies in your aquarium.

With this nitrifying bacteria supplement, you can add fish to your aquarium right away without worrying about having an unstable environment. However, keep in mind that this product should be regularly used to maintain your aquarium.

Unfortunately, it has a rotten smell, and it also has a short shelf life. To prolong its shelf life, store it properly in a cool and dark place.


  • Boasts different bacteria strains
  • Offers quick results


  • Specific storage requirements
  • Bad smell

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5. Dr Tim’s Nitrifying Bacteria

DrTim’s Aquatics Freshwater One & Only Live Nitrifying Bacteria – Eliminate New Tank Syndrome for New Fish Tanks, Aquariums, & Water Filtering & Treatment - Treats 120gal - 8oz

Want to find a product that works instantly to eliminate toxic buildup to prevent New Tank Syndrome? Dr. Tim’s Nitrifying Bacteria is worth considering.

If you notice your fish dying due to random spikes in ammonia levels, adding this product will quickly restore your aquarium within ten days of application. This is great if you want to cycle new tanks or sort your new filters.

This product works by controlling the nitrite and ammonia levels and naturally removing toxic substances in saltwater and freshwater aquariums. This product is also odor and sulfur-free. Therefore, your fish can immediately go back into the aquarium after using it.

Remember that you need to purchase a new bottle from the company because the bacteria may die in the older bottles, making them useless for your aquarium. You also need to use ammonia drops with this product to work faster.


  • You can immediately add fish
  • Great for new tanks
  • Naturally removes toxins
  • It does not have a bad smell


  • Short shelf life
  • It needs to be used alongside ammonia drops

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6. API Quick Start Nitrifying Bacteria

API QUICK START Nitrifying Aquarium Bacteria, Allows Instant Addition of Fish and Maintains Active Biological Filter, 16-Ounce Bottle

This product is marketed as a cleaner so you can add new fishes to your aquarium instantly, but make sure to check the ammonia and nitrates in the water first.

The most impressive feature of this product is it dramatically reduces ammonia in your aquarium more than other options. The bottle is also big enough to last a long time.

Another great thing about this product is that it can reduce the harmful compounds in your aquarium, making it safer for your fish with routine use.

This product does not contain ammonia, so don’t forget to add some before putting it in. It’s worth noting that the API Quick Start Nitrifying Bacteria works best on old aquariums, so you may still encounter “new tank syndrome” if you’re not careful.


  • Great for routine use
  • Recommended for old aquariums
  • Can salvage emergency problems related to bacterial colonies


  • It needs ammonia to jumpstart it
  • Not great for new aquariums

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7. Tetra Cleaning Aquarium Bacteria

Tetra Cleaning Bacteria 8 Ounces, For A Clean Aquarium And Healthy Water, PHL309494

This is such an easy product to use. All you need to do is add a couple of drops to your aquarium every month. One cap-full is considered a full dose.

The Tetra Cleaning Aquarium Bacteria can reduce the general waste in your water and ensure that the level of good bacteria is healthy. It can also improve filtering processes and balance the water.

What’s great about this bacteria supplement is it lessens your need to change your filter. It also helps with algae growth.

However, this product can be dangerous if you don’t follow the recommended dose because it can damage delicate fish in your aquarium. In addition, several species of fish can develop infections if they are not used to the presence of this bacteria.

Instead of helping your aquarium thrive, the addition of this best nitrifying bacteria supplement for a freshwater aquarium will only stress the fish.


  • Reduces ammonia and nitrate levels
  • It keeps the water balanced
  • Reduces aquarium cleaning time
  • Helps with algae growth


  • Not great for delicate fishes
  • Can cause bacterial infections to some fishes

Try Tetra Cleaning Bacteria

When Should You Add Bacteria Supplements?

This section will look at when you should add the best nitrifying bacteria supplement for a freshwater aquarium.

New Tank Cycling

Cycling is a term that refers to the biological maturation of aquariums, and beneficial bacteria are responsible for nitrogen cycles in aquariums.

Tanks must get cycled before fish are added to ensure no toxic buildup that will cause fish to die. Adding beneficial bacteria from the onset will help speed up your tank’s cycling process.

When Adding New Fish

If you add new fish to your aquarium, you should add a nitrifying bacteria supplement. This is because the introduction of new fish results in more waste, and the current level of bacteria in your aquarium may not catch up with the new addition.

This is why you should add bacteria alongside the new fish.

After Water Changes

Even if you’re only partially changing your aquarium’s water, you need to add a nitrifying bacteria supplement. This is because even a small change can disrupt the established bacteria levels in your tank.

If you fail to add bacteria, the pH levels of your aquarium will not be balanced.

Related : Check out our list of the Best Nitrate Remover for a freshwater aquarium.

When Medicating Your Fish

If you are an aquarist, you already know that there will inevitably come when you have to treat sick fish with antibiotics. Antibiotics will sleep up the healing time of fishes, but it also has drawbacks, including killing the bacteria that live in your aquarium.

This is why you need to replenish your beneficial bacteria supply by adding more to your tank.

Frequently Asked Questions

Still, got questions about the best nitrifying bacteria supplement for a freshwater aquarium? Here are some FAQs about it.

How Often Should You Use A Bacteria Supplement?

This is one of the most common questions of newbie aquarists. You should add bacteria supplements to your aquarium whenever on a new tank cycling, or whenever you are medicating your fishes, and when you add new fish to the tank.

Most importantly, add bacteria supplement when you partially or entirely change the water. For example, the recommended schedule for smaller tanks is to change 10% to 15% of the water every week.

Therefore, you should add a nitrifying bacteria supplement four times a month. Following this tip will ensure your aquarium remains healthy and balanced.

Can You Add Too Much Nitrifying Bacteria?

Yes. Although the bacteria levels in your aquarium will settle in time, it may cause your fish to get sick. This is why you have to be careful in adding nitrifying bacteria supplements.

Thankfully, this can be prevented by installing a reliable working filter and following the tips on adding nitrifying bacteria listed above.

Can You Add Bacteria When Fish Are in The Aquarium?

We recommend you give your aquarium time to settle before adding the fish. This can be as long as 48 hours. However, there are also products where you can add the fish instantly. But make sure to check the ammonia and nitrite levels first.

What Is the Best Starter Bacteria For Freshwater Aquariums?

Adding the best nitrifying bacteria supplement for freshwater aquarium is a must if you want to maintain your fishes’ health.

Our Top Pick!

  • 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.

Check Price Now

When it comes to the most effective bacteria supplement you can try, SeaChem Stability is the clear winner. This supplement is straightforward to use, and you don’t have to worry about poisoning your fish with it. With its affordability and efficacy, it will genuinely give you the best value for your money. Try it out and see how well it performs.

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