Forktail Blue-eye: tank size, group & compatibility data

Stocking notes

Small energetic rainbowfish relatives that prefer groups and good surface movement.

For planning, StockingLab models Forktail Blue-eye at its approximate adult size rather than the juvenile size commonly seen in shops. That matters because space use and waste production can change dramatically as fish mature.

What the calculator checks

• Whether the tank's usable volume is below the 55 L / 14.5 US gal reference minimum.
• Whether the selected group is below the planner's typical 8 fish social starting point.
• Whether target temperature and pH sit inside the planning range.
• Whether prospective tankmates create predation, fin-nipping, territorial or water-overlap conflicts.
• Whether too many fish accumulate in the same top swim zone.

Before buying

Use this profile as a shortlist tool, not as a substitute for a dedicated care source. Confirm adult size, diet, sex ratio, habitat structure and locally relevant water conditions before purchase.

How to interpret this Forktail Blue-eye profile

At roughly 5 cm / 2.0 in adult length, Forktail Blue-eye should be planned at mature size rather than the smaller size commonly offered for sale. The reference tank is 55+ L / 14.5+ US gal, with a planning water window of 24–28°C and pH 7–8.2. A midpoint around 26.0°C and pH 7.6 is useful only as a comparison aid; the aim is stable water that overlaps the needs of the whole community.

The profile starts from a social group of 8+ because this is a strongly group-oriented species; planning only one or two would understate both its welfare needs and the space used by a proper group. Its modeled waste factor is relatively modest at 0.70×, but that does not make the 55 L reference tank optional: swimming room, social structure and oxygen demand are separate constraints. Activity is modeled at 1.20×, which makes horizontal swimming length and unobstructed space more important than litres alone.

Common planning mistakes to avoid

• Keep the group at or above the 8+ planning starting point before adding extra species.
• Prioritise tank length and open swimming room when comparing aquariums with similar volume.
• Check that the planned temperature sits inside the shared 24–28°C range for every species in the community.
• Use the 55 L / 14.5 US gal reference as a starting point, then let actual tank dimensions, filtration and the full stock list refine the decision.

Bottom line: the profile is designed to screen a proposed aquarium for obvious pressure points. A result that passes StockingLab still needs to be checked against current, species-specific husbandry information for Pseudomugil furcatus, especially diet, breeding behavior, sex ratio and habitat structure.