Start a guppy community with water chemistry, fin safety and a plan for breeding. Choose peaceful companions suited to your measured water, rather than buying fish just because they look small and colourful.
Read the guppy care guide →Decide how you will manage reproduction before stocking. A mixed-sex livebearer tank can change quickly, and females may already be carrying young. The calculator evaluates only the quantities you enter; it does not forecast fry.
Each example uses a 20-gallon long with six guppies and one companion group. These are comparison plans, not instructions to combine every row. Use the exact adult fish and counts you intend to keep, including changes as young grow.
Each card is one separate example. The model’s result and the editorial guidance answer different parts of the decision.
A livebearer community to plan carefully
Platies are a useful option to compare where the water suits both species. They are also livebearers, so this combination makes population planning more important, not less.
Example: 6 guppy + 4 Platy in a 20-gallon long.
No blockers or warnings in this example’s current checks. Individual behaviour and breeding still need your judgment.
A different swimming level
A social cory group adds bottom activity. Check the actual shared water range, provide appropriate substrate and feed the corys directly instead of relying on guppy leftovers.
Example: 6 guppy + 6 Panda cory in a 20-gallon long.
No blockers or warnings in this example’s current checks. Individual behaviour and breeding still need your judgment.
Not a default companion
A betta’s response to guppy tails can be unpredictable. Even if the current model lists no conflict, choose another direction unless you can observe closely and immediately provide separate suitable housing.
Example: 6 guppy + 1 Betta in a 20-gallon long.
No blockers or warnings in this example’s current checks. Individual behaviour and breeding still need your judgment.
Do not use a predator as a substitute for a breeding plan or assume a “peaceful” label prevents fin damage. Long-finned varieties can be vulnerable, and individual behaviour still needs observation.
Compare complete communities by tank size →They can be considered together when your measured water fits both and the tank has enough adult space. Plan for reproduction in both species; the example counts are not a forecast of the future population.
Only fish you enter are included. Update the plan as the population changes and arrange suitable homes before the tank becomes crowded.
No. Add corys only if you want to keep and care for a full social group. They need their own food and do not replace substrate cleaning or water changes.
Original companion-selection guidance: curated-v0 (needs expert review), medium confidence. Model comparisons use data 0.3.0. Care values retain their field-level sources in the linked species profiles. These pages are not expert-reviewed compatibility guarantees.
Further reading from the guppy care guide
How we handle sources and corrections →
