AquariumStocking

    Fish Stocking Calculator

    Plan your perfect tank with our intelligent stocking tool

    Looking for inspiration? Browse Biotope Presets →

    Stocking calculator

    Tank Setup

    Display units:
    Temperature:

    Enter your tank dimensions

    Enter your tank volume directly

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    Unlike outdated inch-per-gallon rules, we use modern fishkeeping science to help you build a thriving aquarium.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

    FeatureAquariumStockingAqAdvisor
    Modern UIYesNo
    Mobile-FriendlyYesNo
    Planted TankYesLimited
    FiltrationYesAdvanced
    Real-TimeYesNo
    MaintenanceYesNo
    Species209+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

    1

    Choose Your Tank Size

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

    2

    Cycle Your Tank

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

    Learn about the Nitrogen Cycle
    3

    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
    4

    Add Fish Gradually

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

    5

    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.

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