API STRESS ZYME+ – Beneficial Bacteria Aquarium Cleaner

Quick Answer

API STRESS ZYME+ is a beneficial-bacteria aquarium maintenance product for freshwater and saltwater aquariums.

It contains more than 300 million live bacteria per teaspoonful that help consume:

• Fish waste

• Sludge

• Uneaten food

• Organic debris

Regular use helps keep aquarium gravel and glass cleaner, supports the biological filter and reduces the buildup of organic waste.

This is not a fish medication and does not treat diseases.

Product Overview

Aquarium waste does not only come from visible fish waste. Uneaten food, decomposing organic material and sludge can gradually accumulate in the aquarium, particularly around:

• Gravel

• Rock

• Decorations

• Filter areas

• Other hard-to-clean surfaces

API STRESS ZYME+ introduces beneficial live bacteria that consume organic debris and help maintain a cleaner, more naturally balanced aquarium.

API states that each teaspoon contains more than 300 million live bacteria.

When used regularly, STRESS ZYME+ helps:

• Break down sludge and organic debris

• Keep gravel and aquarium surfaces cleaner

• Support an active biological filter

• Maintain good aquarium conditions

• Reduce routine aquarium maintenance over time

It can be used in both freshwater and saltwater aquariums.

Who Is This For?

Suitable for:

• Freshwater aquarium keepers

• Saltwater aquarium keepers

• Betta keepers

• Goldfish keepers

• Tropical community tanks

• Cichlid keepers

• Planted aquariums

• Reef and marine aquarium keepers where used according to the label

• New aquarium setups

• Established aquariums

• Tanks with regular organic-waste buildup

• Hobbyists wanting additional biological maintenance support

Particularly useful for:

• Routine weekly aquarium maintenance

• Aquariums where sludge or organic debris tends to accumulate

• Supporting the biological filter

• New aquarium start-up

• Helping establish additional beneficial bacteria during the first few weeks of a new aquarium

It is NOT specifically for:

• Cats or cat owners

• Treating fin rot

• Treating ich / white spot

• Treating velvet

• Treating fungal infections

• Treating bacterial infections

• Treating parasites

Variant Guide

118 ml / 4 fl oz

Best for: Smaller aquariums or first-time users.

Same STRESS ZYME+ bacterial formula in a smaller bottle.

At the standard weekly dosage of:

5 ml per 38 L

one 118 ml bottle provides approximately 23 standard 5 ml doses.

Larger Bottle

Your current YASAM listing shows:

273 ml

However, this should be checked against your physical stock before publishing.

API's current official product range includes an 8 fl oz bottle, which is approximately 237 ml, not 273 ml.

If your bottle is labelled 237 ml / 8 fl oz, update the YASAM variant from:

273 ml ❌

to:

237 ml / 8 fl oz ✓

Do not change it until you confirm what is printed on your current bottle.

The formulation is the same regardless of bottle size.

Key Specifications

Brand: API
Product: STRESS ZYME+
Product Type: Beneficial Bacteria / Aquarium Cleaner / Biological Maintenance Additive
Form: Liquid
Suitable Water: Freshwater & Saltwater
Primary Function: Organic-waste breakdown and biological-filter support
Live Bacteria: More than 300 million per teaspoonful
Standard Dosage: 5 ml per 10 US gallons / 38 L
Standard Frequency: Weekly
New Aquarium Dosage: Double dose at start-up, followed by regular use for 2 additional weeks
Can Be Added With Fish Present: Yes

Helps Break Down

• Fish waste

• Sludge

• Uneaten food

• Organic debris

Supports

• Biological filtration

• Cleaner aquarium surfaces

• Reduced organic buildup

• Routine aquarium maintenance

Additional Product Notes

Contains Live Beneficial Bacteria

API STRESS ZYME+ contains over 300 million live bacteria per teaspoonful.

These bacteria consume sludge and organic debris that accumulate in the aquarium.

This biological action is different from simply chemically clarifying the water.

Supports the Biological Filter

API recommends weekly use to help maintain a strong biological filter.

The product can also be used at a higher initial dosage in new aquariums to provide additional bacterial support during start-up.

Helps With Organic Waste — Not Instant Ammonia Detoxification

Fish waste, uneaten food and decomposing organic matter can contribute to poor aquarium conditions.

STRESS ZYME+ helps by breaking down this organic material.

However, it should not be described as an instant ammonia or nitrite remover.

If ammonia or nitrite is detected:

• Test the water accurately

• Check biological filtration

• Review stocking and feeding

• Perform appropriate water changes when necessary

• Address the underlying cause

Do not rely on STRESS ZYME+ alone to correct dangerous ammonia or nitrite readings.

Different From API QUICK START

Although both products contain beneficial bacteria, they are positioned differently.

STRESS ZYME+
→ Regular biological maintenance
→ Breaks down sludge and organic debris
→ Helps keep the aquarium clean
→ Used weekly

API QUICK START
→ Primarily designed to introduce nitrifying bacteria when starting an aquarium
→ Used to help establish the nitrogen cycle in new setups

They should not be described as exactly the same product.

Different From API STRESS COAT

Despite the similar name:

STRESS ZYME+ = beneficial-bacteria cleaner

STRESS COAT = water conditioner used for treating tap water and removing chlorine/chloramines

STRESS ZYME+ should not be used as a substitute for dechlorinator when preparing untreated tap water.

How To Use

Routine Weekly Maintenance

1. Shake the bottle well.

2. Determine the aquarium's water volume.

3. Add:

5 ml per 10 US gallons / 38 L

4. Add directly to the aquarium.

5. Repeat once weekly as part of regular aquarium maintenance.

Examples

10 L aquarium: approximately 1.3 ml
20 L aquarium: approximately 2.6 ml
38 L aquarium: 5 ml
76 L aquarium: 10 ml
100 L aquarium: approximately 13 ml

For New Aquariums

API instructs users to:

1. Double the normal dose at aquarium start-up.

2. Continue using the product for 2 additional weeks.

3. Thereafter, use the normal weekly maintenance dosage.

Standard dosage:

5 ml per 38 L

Initial new-aquarium dosage:

10 ml per 38 L

Then continue according to the manufacturer's current instructions.

Can It Be Added With Fish Inside?

Yes.

API specifically states that STRESS ZYME+ can be added while fish are in the aquarium.

Always shake well before dosing and follow the dosage on the current bottle.

Good To Know Before Buying

This is NOT fish medication

STRESS ZYME+ should not be marketed as a treatment for fish symptoms or disease.

It does not specifically treat:

• Fin rot

• Ich

• Velvet

• Fungus

• Bacterial infections

• Parasites

Its purpose is aquarium biological maintenance and organic-waste breakdown.

It is not a dechlorinator

STRESS ZYME+ does not replace a water conditioner such as API STRESS COAT when untreated tap water contains chlorine or chloramine.

Treat new tap water with an appropriate dechlorinator as required.

It does not replace water changes

Beneficial bacteria can help process organic material, but regular aquarium maintenance is still necessary.

Continue to:

• Test important water parameters

• Perform appropriate partial water changes

• Remove excessive debris

• Maintain filtration

• Avoid overfeeding

• Avoid overstocking

It is not an instant fix for high ammonia or nitrite

If ammonia or nitrite levels are elevated, investigate the cause immediately.

STRESS ZYME+ supports biological aquarium maintenance, but it should not be presented as a product that instantly neutralises dangerous ammonia or nitrite.

Use weekly

API's standard maintenance recommendation is:

5 ml per 38 L once weekly.

For new aquariums, API recommends double the initial dose and continued use for the following 2 weeks.

Shake well before use

The product contains live bacterial cultures, and API specifically instructs users to shake the bottle well before dosing.

Suitable for freshwater and saltwater

Unlike many aquarium products designed only for freshwater fish, API officially lists STRESS ZYME+ for both freshwater and saltwater aquariums.

Check the YASAM larger-size variant

Before purchasing or updating the listing, check the bottle label carefully.

YASAM currently lists 273 ml, while API's official range includes an 8 fl oz size of approximately 237 ml.

This may simply be a typo in the existing YASAM product data.