Can Electric Blue Crayfish live with Harlequin Rasbora?
Case-by-case. Watch group sizes, tank size, and feeding zones.
Why Electric Blue Crayfish and Harlequin Rasbora Don't Make an Easy Pair
They can coexist, but you need to manage the setup carefully. The temperament combination (aggressive+peaceful) can work, but you will need to watch them at feeding time for the first week.
Electric Blue Crayfish
Procambarus alleni
| Adult Size: | 6.0" |
| Temperament: | aggressive |
| Min Tank: | 30 gal |
| Temperature: | 65-80°F |
| pH Range: | 6.5-8.0 |
Harlequin Rasbora
Trigonostigma heteromorpha
| Adult Size: | 2.0" |
| Temperament: | peaceful |
| Min Tank: | 10 gal |
| Temperature: | 73-79°F |
| pH Range: | 5.5-7.0 |
Water Parameter Overlap
| Parameter | Electric Blue Crayfish | Harlequin Rasbora | Overlap |
|---|---|---|---|
| Temperature | 65-80°F | 73-79°F | 6°F ✓ |
| pH | 6.5-8.0 | 5.5-7.0 | 0.5 ✓ |
Compatibility Breakdown
Temperament Match: aggressive + peaceful. One aggressive → predation/nipping risk.
⚠️ Size Predation Risk: Electric Blue Crayfish (6.0") vs Harlequin Rasbora (2.0"). A 4.0" gap — the larger fish will view the smaller fish as food.
Score: 55.0/100 (GOOD ≥80, CAUTION ≥50, RISKY <50).
🔧 Tank Setup Requirements (for Both)
- Minimum tank: 30 gallons — sized for the larger fish in the pair.
- Temperature: keep it between 73°F and 79°F.
- pH: maintain 6.5 – 7.0.
- Hiding spots: essential for Harlequin Rasbora — caves, plants, or driftwood to retreat when feeling stressed.
- Water changes: 25% weekly minimum. Two species mean double the bioload.
🔧 Tank Stocking Calculator
Enter tank size to calculate safe stocking levels:
Recommended Equipment
Based on tank size 30+ gallons:
Sinking food for crayfish and crustaceans
Explore Related Checks
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Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a aggressive individual Electric Blue Crayfish may act differently from its species average. Always observe, quarantine new arrivals for 2-4 weeks, and avoid overcrowding. If a pairing says CAUTION, start with a smaller group and a lid.