Can Red Tail Black Shark live with Serpae Tetra?
Case-by-case. Watch group sizes, tank size, and feeding zones.
Why Red Tail Black Shark and Serpae Tetra Don't Make an Easy Pair
They can coexist, but you need to manage the setup carefully. The temperament combination (semi-aggressive+semi-aggressive) can work, but you will need to watch them at feeding time for the first week.
Red Tail Black Shark
Epalzeorhynchos bicolor
| Adult Size: | 5.0" |
| Temperament: | semi-aggressive |
| Min Tank: | 30 gal |
| Temperature: | 72-80°F |
| pH Range: | 6.5-7.5 |
Serpae Tetra
Hyphessobrycon eques
| Adult Size: | 2.0" |
| Temperament: | semi-aggressive |
| Min Tank: | 20 gal |
| Temperature: | 72-79°F |
| pH Range: | 5.5-7.5 |
Water Parameter Overlap
| Parameter | Red Tail Black Shark | Serpae Tetra | Overlap |
|---|---|---|---|
| Temperature | 72-80°F | 72-79°F | 7°F ✓ |
| pH | 6.5-7.5 | 5.5-7.5 | 1.0 ✓ |
Compatibility Breakdown
Temperament Match: semi-aggressive + semi-aggressive. Semi-aggressive → watch territory and feeding.
⚠️ Size Predation Risk: Red Tail Black Shark (5.0") vs Serpae Tetra (2.0"). A 3.0" gap — the larger fish will view the smaller fish as food.
Score: 70.0/100 (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 72°F and 79°F.
- pH: maintain 6.5 – 7.5.
- Hiding spots: essential for Red Tail Black Shark — 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:
High-quality flake food for community fish
Explore Related Checks
See what else works with these fish:
⚠️ Common Reasons This Pairing Fails in Practice
- Size-based predation: The 3.0" size gap means the larger fish may eat the smaller one once it grows to full size. This is not fixable with more hiding spots.
- Double semi-aggressive: Two territorial species in the same tank creates competition for prime real estate. Provide distinct territories or expect fin-nipping and chasing.
- Overcrowding: Even compatible species fail in tanks that are too small. Double the species means double the bioload — 25% weekly water changes are the minimum.
- Inadequate acclimation: Adding both species on the same day without quarantine is a common mistake. Always drip-acclimate new arrivals and quarantine for 2–4 weeks.
Tools & Resources
Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a semi-aggressive individual Red Tail Black Shark 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.