Compatibility Report
GuideMyTank compatibility analysis for Freshwater Butterflyfish and Harlequin Rasbora.
Planning verdict
incompatibleDo not plan a shared aquarium for this pair. Choose a different tank mate or maintain separate aquariums.
Freshwater Butterflyfish and Harlequin Rasbora receive a not recommended verdict from the current structured assessment. Freshwater Butterflyfish is recorded as semi-aggressive with an aggression level of 4/10; Harlequin Rasbora is recorded as peaceful with an aggression level of 1/10. The recommendation is based on the combined water, space, behavior, grouping, and predation checks below rather than on species names alone.
Freshwater Butterflyfish has a recorded temperature range of 73–86°F and pH range of 6.5–7.2. Harlequin Rasbora is recorded at 73–82°F and pH 6–7.5. Their shared planning window is 73–82°F for temperature and 6.5–7.2 for pH. A shared aquarium must stay inside the overlap rather than merely touching each species’ outer tolerance.
Freshwater Butterflyfish sets the larger listed base aquarium requirement at 30 gallons; the other listed minimum is 20 gallons. Freshwater Butterflyfish is the larger adult by the recorded maximum, reaching 5 inches, compared with 2 inches. These figures are starting constraints, not a stocking-capacity calculation, because the complete group sizes and bioload still matter.
Freshwater Butterflyfish is a moderate species associated with the top zone and low flow. Harlequin Rasbora is active, uses the mid zone, and has a moderate flow preference. Freshwater Butterflyfish does not have a recorded minimum school larger than one, while harlequin rasbora should be planned as a group of at least 8. The aquarium must support both social structures without forcing either species into insufficient space.
Freshwater Butterflyfish is recorded as a carnivore with advanced care, while Harlequin Rasbora is a omnivore with easy care. Their listed preferred tank styles are blackwater and blackwater. Feeding access, cover, open swimming room, filtration, and observation should be planned around the more demanding requirement rather than averaged between the two species.
Use these pair-specific boundaries before treating the verdict as an acceptable stocking plan.
Do not plan a shared aquarium for this pair. Choose a different tank mate or maintain separate aquariums.
These references support the underlying species records used by this assessment. They do not necessarily evaluate this exact pair together.
Continue with the most relevant care and compatibility resources for Freshwater Butterflyfish and Harlequin Rasbora.