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Compatibility

Compatibility brief

Can Jack Dempsey live with Rummy Nose Tetra?

Jack Dempsey

Jack Dempsey

Rocio octofasciata

aggressive~25cm
Rummy Nose Tetra

Rummy Nose Tetra

Hemigrammus rhodostomus

peaceful~5cm
VerdictRISKY

Risky. This mix is commonly discouraged for typical setups.

Jack Dempsey + Rummy Nose Tetra: Aggression mismatch. Jack Dempsey is aggressive, while Rummy Nose Tetra 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 °C24–28°C shared
Jack DempseyRummy Nose TetraShared window
pH
Range6.5–7 shared
Jack DempseyRummy Nose TetraShared window
Size / predation

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

Temperament / behaviour

Jack Dempsey (aggressive) and Rummy Nose Tetra (peaceful) 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 Rummy Nose Tetra is peaceful. The aggressive fish will likely bully or harm the peaceful one.

  2. Jack Dempsey may eat Rummy Nose Tetra

    Jack Dempsey (25cm) is predatory and Rummy Nose Tetra (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 Rummy Nose Tetra is peaceful”

Aggression mismatch

Next steps

Concrete changes, not "research more" filler.

  • •Rummy Nose Tetra should be kept in a group of at least 8 for best health and behaviour.

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. 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.

  • Seriously Fish. Hemigrammus rhodostomus

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

  • FishBase. Hemigrammus rhodostomus

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

  • Wikipedia. Hemigrammus rhodostomus

    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 Jack Dempsey + Rummy Nose Tetra

Compare another pairOpen tank builder

Plan further

Check each species’ mates list, size the glass, then verify the full stock in the builder. 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. Checked against several solid care sources that mostly agree.

Full tank-mate guides

Related pair checks

Other tank mates for Jack Dempsey

Jack Dempsey + Rummy Nose Tetra — common questions

Can Jack Dempsey live with Rummy Nose Tetra?
For most keepers, no. The verdict is RISKY: at least one check fails hard for a typical home tank. Choose a different pairing, or read the assessment details on this page to see exactly what fails before deciding.
What tank size do you need for Jack Dempsey and Rummy Nose Tetra together?
Plan around 200 litres as the working minimum. That figure comes from each species' published minimum and their group needs, and it assumes adult sizes, not shop sizes.
What's the main risk?
Aggression mismatch. That is the check that fails outright for this pair. The matching entry under assessment details on this page explains the reasoning and the numbers behind it.
What should you check before buying?
Rummy Nose Tetra should be kept in a group of at least 8 for best health and behaviour.