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Compatibility

Compatibility brief

Can Guppy live with Jack Dempsey?

VerdictRISKY

Risky. This mix is commonly discouraged for typical setups.

Guppy + Jack Dempsey: Aggression mismatch. Jack Dempsey is aggressive, while Guppy is peaceful. The aggressive fish will likely bully or harm the peaceful one. Real tanks add variables Fishori cannot model; treat this as a high-risk read, not certainty.

Compatibility score

30/100

Profile confidence: medium

Order of checkstank volume vs adults → predation mouth gap → temperament / fin nipping → shared water windows.

Min tank

200L

Combined minimum footprint reference for these two species: about 200L (larger active fish often want more length).

Temperature
Range in °C2228°C shared
GuppyJack DempseyShared window
pH
Range6.87.8 shared
GuppyJack DempseyShared window
Size / predation

Jack Dempsey (25cm adult) may treat small Guppy (~5cm) as food once grown — plan adult sizes, not shop sizes.

Temperament / behaviour

Guppy (peaceful) and Jack Dempsey (aggressive) are far apart on aggression — bullying or injury is a common outcome in average community layouts.

Assessment details

  1. Aggression mismatch

    Top issue

    Jack Dempsey is aggressive, while Guppy is peaceful. The aggressive fish will likely bully or harm the peaceful one.

  2. Jack Dempsey may eat Guppy

    Jack Dempsey (25cm) is predatory and Guppy (5cm) is small enough to be eaten. This pairing is unsafe.

  3. Compatible temperature range

    Both fish can comfortably share similar water temperatures.

Jack Dempsey is aggressive, while Guppy is peaceful

Aggression mismatch

Next steps

Concrete changes, not "research more" filler.

Try instead

  • Build a species-only tank for the larger fish, or restock with fish too large to be eaten at adult sizes.
Sources from both profiles
Only URLs that exist on the species records are shown. We do not fabricate citations.
  • Seriously Fish. Poecilia reticulata

    Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).

  • FishBase. Poecilia reticulata

    Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.

  • Wikipedia. Poecilia reticulata

    Secondary: general species context; verify all husbandry numbers against a dedicated aquarium care sheet and your test kit, not a single table row.

  • Wikipedia. Guppy

    Encyclopaedia overview; use specialist aquarium sources for your stock's real temperature/pH/footprint needs.

  • Seriously Fish. Rocio octofasciata

    Primary: aquarium size, water chemistry, behaviour, and compatibility (URL verified in upgrade script; recheck if site content changes).

  • FishBase. Rocio octofasciata

    Secondary: taxonomy, distribution, and maximum length in nature; cross-check with aquarium import lines and measured tank parameters.

  • Wikipedia. Rocio octofasciata

    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 Guppy + Jack Dempsey

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.

Related pair checks

Other tank mates for Guppy

Instead of Jack Dempsey, consider

These are among Guppy's safer tank mates on file — check each pair individually.