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Our database includes over 500+ freshwater species to help you plan your ideal aquarium!
Step 2: Filtration
Step 3: Add Fish
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Version: 2.2.4 / Last Updated: [17-02-2026]
IMPORTANT NOTE: Read before you apply our recommendations!
Plan a safer, more balanced fish list using tank volume, tank footprint, adult size, temperament, and filtration turnover.
This calculator shows results using three stocking rules:
- Modern (Balanced & Practical) – recommended for real freshwater community tanks
- UK old school (1 cm per litre) – included for comparison
- 1 inch per gallon – a basic starting point
Important: This tool is a planning guide, not a guarantee. Fish behaviour, feeding, plants, filter media, and maintenance habits change real-world outcomes. If you spot incorrect fish or filter data, email us at support@aquastream.in.
Plan a Safer Fish List (Stocking + Compatibility + Filter Turnover)
Stocking affects water quality, stress, aggression, algae, and how often you need maintenance. This tool helps you:
- Check if your plan is comfortable, near the limit, or high risk
- Compare results across multiple stocking rules (Modern, UK, inch/gal)
- Get practical guidance for turnover, compatibility, and weekly water changes
What the calculator checks
1) Stocking level
The Modern rule uses a practical load model that adjusts for adult size and behaviour (not just “fish count”). The older rules are mainly for comparison.
2) Filtration turnover
Turnover is calculated using effective flow, not just box-rated flow. The target turnover increases as stocking load increases (higher load = higher flow needed).
3) Compatibility score
A quick safety score based on temperament mix and overlap of core ranges (temperature, pH, hardness).
It’s a helpful warning system, not a guarantee.
4) Weekly water change suggestion
A practical weekly water change estimate based on stocking level, then adjusted by filtration performance.
Freshwater Fish Database
The calculator uses an in-built fish list with common freshwater species and key care ranges such as adult size, minimum tank size, and temperament. We expand this list over time.
Update: We recently added 500+ freshwater fish species to improve coverage.
If you can’t find a fish:
- Search by scientific name
- Try a close species and select a safer size option
- Request an addition at support@aquastream.in
Aquarium Filter Database
We include a built-in filter database so you can estimate turnover faster without guessing.
What this helps with:
- Faster planning when you don’t know your filter’s real-world flow
- Easier comparison between filters before purchase
- Turnover shown using effective flow, not only box-rated flow
Current filter database size:
- Total filter models: 406
- Canister: 160
- Internal: 135
- HOB: 100
- Top filter: 8
- Sponge: 3
Note: Real-world flow depends on media, height, clogging, spray bar, and maintenance. This calculator uses effective flow to stay realistic.
Data is compiled from manufacturer specs plus hobbyist experience. If a spec looks wrong, email support@aquastream.in.
How to Use This Fish Tank Stocking Calculator
- Enter tank volume, or add dimensions to estimate it
- Select water type and aquascape style
- Choose a filter from the list to compare turnover
- Search and add your fish, then click Calculate
- Use the Stocking Rule switch in the results to compare all three methods
How to Read the Stocking Analysis Results
1) Bioload units
A relative load score based on adult size and waste level. Higher bioload usually means higher maintenance and stronger filtration needs.
2) Stocking level percent
Shows how close your plan is to the recommended limit for the selected rule:
- Under 80% = usually comfortable
- 80–100% = close to the limit
- Over 100% = higher risk and more maintenance
3) Compatibility score
A quick safety score based on temperament mix and overlap of key ranges (temperature, pH, hardness). Always consider tank layout and individual fish behaviour.
4) Filtration turnover
Your estimated turnover per hour using effective flow, compared against a target that scales with stocking load.
5) Weekly water change
A practical weekly water change suggestion based on stocking level and filtration performance. Heavy feeding or messy fish may need more.
6) Recommended temperature, pH, and hardness
An overlap range based on your selected fish. If overlap is low, the tool warns you because keeping fish outside their range increases stress and disease risk.
About the old rules
The “1 inch per gallon” and “1 cm per litre” rules are popular, but they don’t account well for:
- Filtration turnover and real-world flow
- Fish behaviour and aggression
- Adult size impact on waste
That’s why the Modern rule is recommended as the primary result. In this calculator:
- Adult size is used because juveniles grow fast and change the load
- Effective flow is used because real filters rarely deliver full box-rated flow
- Results are meant for freshwater community tanks
- Do note that breeding, high-tech planted tanks, and predator tanks need extra caution
What Makes This Stocking Calculator Different
Many calculators only use one rule and ignore filtration and temperament. This calculator is designed to be more practical by including:
- Three stocking rules (Modern + two classic comparisons)
- A built-in filter database (323 models) for faster turnover estimates
- Effective flow and a target turnover that scales with stocking load
- Compatibility scoring + overlap ranges for temperature, pH, and hardness
- A practical weekly water change suggestion based on load + filtration
If you want, you can treat this as a smart second opinion alongside other tools and species research.
Is This an Alternative to AqAdvisor or Similar Tools?
It can be used as an alternative or a second opinion. Many hobbyists like to cross-check stocking plans using more than one tool, then confirm with:
- species-specific care references
- real tank observation (stress, chasing, fin damage, hiding)
- basic water tests (ammonia/nitrite/nitrate)
Different tools use different models, so using two sources is often safer than relying on one.
Why are some fish not listed?
1) Colour morphs aren’t separate species
Colour variants don’t change space needs. Example: a Platinum Guppy has the same needs as a standard Guppy.
2) Hybrids may lack reliable data
Some crossbreeds aren’t listed. Use the closest parent species as a reference.
3) Regional names vary
The same fish may appear under a different common name. Try scientific names.
How Many Fish Can I Keep in My Tank? (Litres & Gallons)
There’s no single perfect number because adult size, waste, and behaviour matter. Use your exact fish list for the safest result. Quick guidance:
- 1000L: allows more fish, but adult size and compatibility still matter
- 10L–20L: best for very limited stocking and strict maintenance
- 60L: more stable and flexible
How many fish can I keep in a 10L, 20L, 60L, or 1000L tank?
- Small tanks like 10L and 20L are best for a very limited stocking plan and stable maintenance.
- Mid tanks like 60L offer more stability and better stocking flexibility.
- Large tanks like 1000L allow more fish, but adult size and compatibility still matter.
Frequently Asked Questions (FAQs)
This calculator is built for freshwater tanks. Saltwater stocking works differently.
It is a planning guide. It can be very useful, but real-life results depend on feeding, plants, filter media, and maintenance.
Reduce load, upgrade filtration, or choose a larger tank. Over 110% usually means higher risk.
Some invertebrates may be listed. Stocking rules and compatibility are focused mainly on fish.
It depends on adult size, waste level, and behaviour. Enter your tank and your planned fish list to get stocking level, filtration turnover, and water change guidance.
A planted tank can improve stability and reduce nitrates, but it doesn’t cancel out swimming space, aggression, or oxygen needs. Treat plants as a buffer, not a free pass. If your stocking is near the limit, keep filtration strong and follow the suggested weekly water change.
Use the results as a “future-safe” baseline. This calculator assumes adult size because juveniles grow fast, and their waste load increases. If your plan looks close to the limit now, it will usually be over the limit later unless you upgrade the tank, reduce stock, or improve filtration and maintenance.
Search by scientific name, or pick the closest similar fish and choose a safer size option. You can also request additions at support@aquastream.in.
About Aquastream
AquaStream is built by hobbyists focused on practical, India-friendly aquarium tools. We update calculators using feedback and real tank results. Email suggestions to support@aquastream.in.
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