Guppy: tank size, group & compatibility data

Stocking notes

A prolific livebearer; plan for fry or single-sex groups and avoid persistent fin-nippers.

For planning, StockingLab models Guppy at its approximate adult size rather than the juvenile size commonly seen in shops. That matters because space use and waste production can change dramatically as fish mature.

What the calculator checks

• Whether the tank's usable volume is below the 40 L / 10.6 US gal reference minimum.
• Whether the selected group is below the planner's typical 3 fish social starting point.
• Whether target temperature and pH sit inside the planning range.
• Whether prospective tankmates create predation, fin-nipping, territorial or water-overlap conflicts.
• Whether too many fish accumulate in the same top swim zone.

Before buying

Use this profile as a shortlist tool, not as a substitute for a dedicated care source. Confirm adult size, diet, sex ratio, habitat structure and locally relevant water conditions before purchase.

How to interpret this Guppy profile

At roughly 5 cm / 2.0 in adult length, Guppy should be planned at mature size rather than the smaller size commonly offered for sale. The reference tank is 40+ L / 10.6+ US gal, with a planning water window of 22–28°C and pH 7–8.2. A midpoint around 25.0°C and pH 7.6 is useful only as a comparison aid; the aim is stable water that overlaps the needs of the whole community.

StockingLab starts with 3+ individuals for this profile, so the reference tank has to accommodate the group's adult footprint rather than one specimen. The modeled waste factor is 0.90×, so biological load is only one part of the decision; adult space, group size and swim-zone crowding still need to be checked. Activity is modeled at 1.00×, so the planner balances ordinary movement demand with adult size and top-zone occupancy.

Common planning mistakes to avoid

• Check prospective tankmates for fin-nipping behavior and persistent chasing.
• Treat the pH range of 7–8.2 as a compatibility window, not a target to force with rapid chemical changes.
• Check that the planned temperature sits inside the shared 22–28°C range for every species in the community.
• Use the 40 L / 10.6 US gal reference as a starting point, then let actual tank dimensions, filtration and the full stock list refine the decision.

Bottom line: the profile is designed to screen a proposed aquarium for obvious pressure points. A result that passes StockingLab still needs to be checked against current, species-specific husbandry information for Poecilia reticulata, especially diet, breeding behavior, sex ratio and habitat structure.