What stocking rule does the tank builder use?

The builder estimates stocking using a common inch-per-gallon style guideline: total adult fish length (in inches) compared to tank volume (US gallons). It is a rough guide only—always consider filtration, maintenance, species behaviour, and tank shape.

Can I use any tank size?

Yes. You enter your own length, width, and height (or diameter and height for cylinders) in centimetres or inches. There is no fixed list of “allowed” sizes: from nano tanks to large displays, volume is calculated from the dimensions you provide.

Do I need an account?

No. You can model a tank, search species, and review stocking without signing in. Creating an account lets you save builds and open them again from your profile or a share link.

Where should I go for species care details?

Start from the freshwater index or a fish group, then open individual species pages for care level, temperature, temperament, and compatibility.

Tank builder — 3D preview, volume & stocking

About this tool

The tank builder is an interactive workspace for freshwater aquarists: set aquarium dimensions, preview a 3D tank outline, search our fish database, and see a quick stocking estimate. It is aimed at hobbyists planning community or species tanks who want volume and a rule-of-thumb check before fine-tuning with filtration and real-world observation.

For care requirements, compatibility, and full species write-ups, use our freshwater species index (62 species) and the group pages below—then use the builder above to try dimensions and stocking estimates for your plan.

Supported tank shapes and sizes

Volume is computed from the dimensions you enter. Shapes include standard rectangle, long (lowboy), tall (column), cylinder, and bow-front. Switch units between cm and inches; results show litres and US gallons.

Rectangular and bow-front: length × depth × height
Long / tall presets: same fields, different default proportions in the 3D preview
Cylinder: diameter × height

How stocking works here

Fish from the database contribute adult size (cm) and quantities you set. The calculator converts to total inches, compares to tank volume in gallons, and classifies the result as understocked, within range, or overstocked. Schooling hints and tank regions in the table support the 3D preview—they are not a substitute for species-specific minimum group sizes on each species page.

What you will see in the builder

At the top of this page (under the title) you get live controls: dimension inputs, species search, a 3D tank visualizer with substrate options, and a stocking summary. This section explains what each part does.

Dimensions & volumeEnter measurements and see litres and US gallons update.

Figure: volume readout from your tank measurements.

3D previewOutline, substrate, and fish movement styles for a quick visual check.

Figure: interactive tank visualizer (in the builder at the top of the page).

Frequently asked questions

What stocking rule does the tank builder use?: The builder estimates stocking using a common inch-per-gallon style guideline: total adult fish length (in inches) compared to tank volume (US gallons). It is a rough guide only—always consider filtration, maintenance, species behaviour, and tank shape.
Can I use any tank size?: Yes. You enter your own length, width, and height (or diameter and height for cylinders) in centimetres or inches. There is no fixed list of “allowed” sizes: from nano tanks to large displays, volume is calculated from the dimensions you provide.
Do I need an account?: No. You can model a tank, search species, and review stocking without signing in. Creating an account lets you save builds and open them again from your profile or a share link.
Where should I go for species care details?: Start from the freshwater index or a fish group, then open individual species pages for care level, temperature, temperament, and compatibility.

Explore fish groups & species

Group hubs introduce whole families of fish; species pages cover care, parameters, and behaviour in depth—use them together with the builder when you plan a tank.

Tank builder