Compatibility brief
Can Betta live with Molly?
Caution. Check the issues below before buying.
Betta + Molly: Caution advised. Water chemistry mismatch and fin risk. Mollies want hard alkaline water (pH 7.5+, hard) and bettas prefer slightly acidic soft. Mollies can also fin-nip a betta in tight quarters. A working tank chooses one set of parameters.
Compatibility score
Profile confidence: medium
Order of checkstank volume vs adults → predation mouth gap → temperament / fin nipping → shared water windows.
80L
Combined minimum footprint reference for these two species: about 80L (larger active fish often want more length).
Temperament gap (semi-aggressive vs peaceful) — can work with space, structure, and careful observation, but not a “drop and forget” mix.
Assessment details
Caution advised
Top issueWater chemistry mismatch and fin risk. Mollies want hard alkaline water (pH 7.5+, hard) and bettas prefer slightly acidic soft. Mollies can also fin-nip a betta in tight quarters. A working tank chooses one set of parameters.
Compatible temperature range
Both fish can comfortably share similar water temperatures.
Narrow pH overlap
These fish can share water but their ideal pH ranges overlap only slightly. Aim to keep pH stable in the shared range.
“Water chemistry mismatch and fin risk”
Caution advised
Next steps
Concrete changes, not "research more" filler.
- •Provide plenty of hiding spots and visual breaks so Molly can escape if harassed.
Try instead
- →Provide plenty of hiding spots and visual breaks so Molly can escape if harassed.
- Seriously Fish. Betta splendens
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Betta splendens
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Betta splendens
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
- Wikipedia. Betta splendens
Encyclopaedia overview; use specialist aquarium sources for your stock's real temperature/pH/footprint needs.
- Seriously Fish. Poecilia sphenops
Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).
- FishBase. Poecilia sphenops
Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.
- Wikipedia. Poecilia sphenops
Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.
Try this next
Build the full stocking list with Betta + Molly
Plan further
Try both species in the full-stock tank check, or open either fish profile for mates lists. Methodology explains how verdicts are produced.
Individual fish vary in personality. Fishori uses conservative hobby rules. Observe any new introduction closely, feed thoughtfully, and keep a quarantine or backup plan. This is not veterinary advice.
Profile data confidence: high. Based on multiple reputable aquarium care sources with strong agreement.