Aquarium Stocking Level Calculator

Calculate safe stocking levels for your aquarium based on tank volume, filtration capacity, and fish species bioload.

Note: This calculator provides general guidelines. Always research specific fish species requirements, compatibility, behavior, and adult size before stocking. Tank dimensions, water quality, and maintenance also affect stocking capacity.
Tip: 1 gallon ≈ 3.78 liters. Calculate: Length × Width × Height (inches) ÷ 231 = gallons

How This Tool Works

This calculator estimates safe stocking levels based on tank volume, filtration capacity, and fish type. It uses bioload calculations (waste production) to determine how many fish your tank can support. The bioload calculation considers the metabolic waste production of different fish sizes and types, as well as your filtration system's capacity to process ammonia, nitrites, and nitrates. The calculator multiplies tank volume by a bioload factor based on filtration quality, then divides by the bioload per fish based on fish size category.

However, this is a general guideline - actual stocking depends on many factors including species-specific requirements, behavior, adult size, and tank dimensions. Some fish produce more waste relative to their size, while others are more sensitive to water quality. Always research specific species requirements and start with conservative stocking levels, especially for new aquariums that haven't fully established their biological filtration.

Important Stocking Considerations

  • Adult Size: Always plan for adult size, not juvenile size
  • Behavior: Active fish need more space than sedentary fish
  • Territoriality: Territorial fish need more space and hiding places
  • Tank Dimensions: Some fish need horizontal space, others need vertical space
  • Compatibility: Not all fish can live together - research compatibility
  • Water Quality: More fish = more waste = more frequent water changes needed
  • Filtration: Better filtration can support higher bioload, but doesn\'t replace adequate space

FAQ

  • What is bioload?
    Bioload refers to the total waste production (ammonia, nitrites, nitrates) from all living organisms in your aquarium. It includes fish, plants, and beneficial bacteria. Higher bioload requires more filtration and water changes.
  • How does filtration affect stocking?
    Better filtration can handle higher bioload, allowing for more fish. High-quality filters with good flow rates, biological media, and proper maintenance can support 20-30% more fish than basic filters. However, always consider fish behavior and space requirements, not just bioload.
  • Is the "1 inch per gallon" rule accurate?
    The "1 inch per gallon" rule is a rough guideline but has limitations. It doesn't account for fish behavior, adult size, bioload differences, or tank dimensions. A 10-inch fish needs much more space and produces more waste than ten 1-inch fish. Always research specific species requirements.
  • What other factors affect stocking?
    Tank dimensions (tall vs. wide), fish behavior (active vs. sedentary), territoriality, adult size, water quality maintenance, and compatibility all affect stocking. Some fish need more horizontal space, others need vertical space. Always research species-specific requirements.
  • Can I stock more if I have plants?
    Live plants can help with bioload by absorbing nitrates, but they don't significantly increase stocking capacity. Plants improve water quality but don't replace proper filtration or reduce the need for adequate space. Focus on appropriate stocking for your tank size and filtration.

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