🌿 Free tool · straight from our care sheets
Compare two fish
Torn between two fish — or want to see how they really stack up? Pick any two and compare what matters for keeping them well, side by side. Every number comes from our fact-checked care sheets, so it can never contradict the full guide.
| 💠 Betta | 🐟 Guppy | |
|---|---|---|
| Difficulty | Beginner | Beginner |
| Group | Bettas & gouramis | Livebearers |
| Adult size | ~7 cm / 2.8 in body (plus flowing fins) | ~3–6 cm / 1.2–2.4 in (females larger than males) |
| Minimum tank | 19 L / 5 US gal minimum for one betta — ~40 L / 11 US gal is better | 19 L / 5 US gal for a small group — ~40 L / 10 US gal is better (they become a colony) |
| Temperature | 24–27 °C / 75–81 °F (within the species range of 22–30 °C / 72–86 °F) | 22–26 °C / 72–79 °F (within the species range of 17–28 °C / 63–82 °F) |
| pH | 6.0–8.0 (ornamental strains are unfussy) | 7.0–8.5 (neutral to alkaline) |
| Hardness (GH) | 1–15 dGH (soft to moderately hard) | 8–30 dGH — a hard-water fish; keep it in moderately hard or harder water long-term |
| Temperament | Bold and curious, but a solitary specialist — not a peaceful community fish | Very peaceful — a model community fish |
| Social / group | Solitary. House one betta per tank; two males will fight, often fatally | Social shoaling fish — keep a group; with mixed sexes keep 2–3 females per male |
| Diet | Carnivore / insectivore — a betta-specific pellet base plus regular small live/frozen foods | Omnivore leaning insectivore — a quality flake/micro-pellet base plus small live/frozen foods |
| Lifespan | 3–5 years with good care | 1–3 years (short-lived; inbred stock often shorter) |
Quick answers
How do I choose between two aquarium fish?
Compare what decides whether you can keep them well, not just looks: difficulty, adult size, minimum tank, water parameters (temperature, pH, hardness), temperament, whether it needs a group, diet and lifespan. A fish that needs hard water, a big tank, or a group of six is a different commitment from one that doesn't. This tool lays those side by side straight from our fact-checked care sheets.
Can I keep these two fish together?
Sometimes — but this tool is for CHOOSING between fish, not confirming they can live together. Whether two species can share a tank depends on temperament, adult size, water parameters and tank size. Use our tankmate compatibility checker for that question; use this tool to compare species you're deciding between.
Are the numbers in this tool reliable?
Yes — they come straight from our species care sheets, each fact-checked against authoritative aquarium and aquatic-vet sources, so the comparison can never contradict the full care sheet. It is honest guidance to help you choose, not a substitute for reading the full sheet or asking a fish-savvy vet.
Why does water hardness matter so much when choosing a fish?
Because it's far easier to keep a fish that suits your tap water than to fight your water chemistry forever. Livebearers like guppies and mollies want harder water; many tetras and dwarf cichlids want soft. Matching the fish to your water (check GH) is one of the biggest, least-talked-about beginner decisions.