Fish Stocking Calculator

Plan your perfect tank with our intelligent stocking tool

Looking for inspiration? Browse Biotope Presets →

Tank Setup

Display units:

Temperature:

Tank Shape

Custom Tank Size

Enter your tank dimensions

Custom Volume

Enter your tank volume directly

Tank Size

Filtration Level

Live Plants

Water Change Frequency

Add Fish

Popular choices:

Current Stock

No fish added yet. Search above or browse to add fish to your tank.

0%Stocked

Empty

Room to add more fish. Consider filling out schools or adding a centerpiece fish.

Compatibility Report

Add fish to see compatibility analysis

Understanding Aquarium Stocking

Proper stocking ensures healthy fish and a balanced ecosystem. Our calculator considers multiple factors that traditional rules ignore:

Bioload — waste production based on species and size
Fish compatibility — aggression levels, water parameters, social needs
Swim level distribution — top, middle, bottom dwellers
Territorial requirements — space and territory needs

Unlike outdated inch-per-gallon rules, we use modern fishkeeping science to help you build a thriving aquarium.

How the Stocking Calculator Works

Bioload Analysis

We calculate waste production based on fish size, species metabolism, and your filtration capacity—not arbitrary rules.

Compatibility Matrix

Our database tracks 209+ species for temperature, pH, aggression levels, and social requirements to prevent conflicts.

Real-World Conditions

We account for planted tanks, filtration quality, and maintenance schedules—factors other calculators ignore.

Swim Level Balance

Ensures fish are distributed across top, middle, and bottom zones for optimal space usage and reduced aggression.

What Makes Us Different

Comparison based on publicly available features as of January 2026. Features and functionality may change.

Feature	AquariumStocking	AqAdvisor
Modern UI	Yes	No
Mobile-Friendly	Yes	No
Planted Tank	Yes	Limited
Filtration	Yes	Advanced
Real-Time	Yes	No
Maintenance	Yes	No
Species	209+	500+

Modern interface, mobile-first design, and accounts for real-world tank conditions like plants and maintenance schedules.

AqAdvisor offers a larger species database (500+ species) and detailed filtration options including specific filter models, which we're working to match as we grow.

5 Common Aquarium Stocking Mistakes

What Do Stocking Percentages Mean?

0-50%: Lightly Stocked

• Easiest to maintain
• Forgiving for beginners
• Fish have plenty of space
• Water parameters stay stable
• Perfect for first-time fishkeepers

50-80%: Moderately Stocked

• Balanced ecosystem
• Requires regular maintenance
• Good for experienced keepers
• Monitor water quality weekly
• Most sustainable long-term

80-100%: Fully Stocked

• Maximum recommended capacity
• Requires excellent filtration
• Frequent water changes needed
• Not recommended for beginners
• Close monitoring essential

100%+: Overstocked

• High risk of ammonia spikes
• Increased aggression and stress
• Disease spreads rapidly
• Not sustainable
• Reduce stock immediately

When to Use the Stocking Calculator

Planning a New Tank

Calculate compatibility before buying fish to avoid returns and losses.

Adding New Fish

Check if your current tank can handle additional species safely.

Troubleshooting Problems

If fish are aggressive or water quality is poor, check if you're overstocked.

Upgrading Your Tank

See how many fish you can add when moving to a larger aquarium.

Comparing Setup Options

Test different stocking scenarios to find the perfect community.

Planning Long-Term

Account for fish growth and future additions to your aquarium.

How Accurate Is This Calculator?

What We Can Predict

Bioload based on species, size, and quantity
Basic compatibility (temperature, pH, aggression)
Swim level distribution
Filtration requirements
Space and territorial needs

What We Can't Predict

Individual fish personalities (some Bettas are peaceful, others aggressive)
Exact water chemistry in your specific tank
Your actual maintenance schedule vs. what you plan
Rare diseases or genetic issues
Unexpected territorial behavior

Our Recommendation: Use this as a guideline, not gospel. Always research individual species thoroughly and have a backup plan for rehoming incompatible fish.

Your First Stocked Aquarium: Step-by-Step

Choose Your Tank Size

Bigger is easier. Minimum 10 gallons for beginners, but 20+ gallons is ideal for stable water parameters.

Cycle Your Tank

BEFORE adding fish, establish beneficial bacteria. This takes 4-6 weeks. Never skip this step.

Learn about the Nitrogen Cycle

Pick a Stocking Strategy

• Species tank — one type of fish in a school
• Community tank — compatible species mix
• Biotope tank — fish from same geographic region

Add Fish Gradually

Add 2-3 fish per week. Monitor parameters between additions. Never add all fish at once—this crashes your cycle.

Monitor & Adjust

Test water weekly for first 3 months. Watch for aggression and stress. Remove incompatible fish immediately if problems arise.

Popular Stocking Plans by Tank Size

10 Gallon Nano

Beginner72% Stocked

• 8 Ember Tetras
• 6 Cherry Shrimp
• 1 Nerite Snail

A colorful nano community. Ember Tetras school beautifully in the midwater while Cherry Shrimp and a Nerite Snail keep things clean.

20 Gallon Community

Beginner74% Stocked

• 1 Honey Gourami
• 6 Harlequin Rasboras
• 3 Amano Shrimp

A centerpiece Honey Gourami leads this peaceful community. Harlequin Rasboras add movement, Amano Shrimp handle algae.

30 Gallon Planted

Intermediate68% Stocked

• 1 Bolivian Ram
• 8 Neon Tetras
• 6 Otocinclus
• 4 Cherry Shrimp

A balanced planted tank. A Bolivian Ram adds personality, Neon Tetras shimmer in schools, Otocinclus graze algae, and Cherry Shrimp keep the substrate clean.

55 Gallon Showpiece

Beginner75% Stocked

• 1 Bolivian Ram
• 12 Neon Tetras
• 8 Cherry Barbs
• 6 Panda Corydoras

A stunning display tank. A Bolivian Ram centerpiece with large schools of Neon Tetras and Cherry Barbs, plus Panda Corydoras patrolling the substrate.

Frequently Asked Questions

Browse All Species

Explore detailed care guides for all 209 species in our database.