Can Common Plecostomus live with Swordtail?
Case-by-case. Watch group sizes, tank size, and feeding zones.
Why Common Plecostomus and Swordtail Don't Make an Easy Pair
They can coexist, but you need to manage the setup carefully. The temperament combination (peaceful+semi-aggressive) can work, but you will need to watch them at feeding time for the first week.
Common Plecostomus
Hypostomus plecostomus
| Adult Size: | 15.0" |
| Temperament: | peaceful |
| Min Tank: | 55 gal |
| Temperature: | 72-86°F |
| pH Range: | 6.5-7.8 |
Swordtail
Xiphophorus helleri
| Adult Size: | 5.0" |
| Temperament: | semi-aggressive |
| Min Tank: | 20 gal |
| Temperature: | 72-78°F |
| pH Range: | 7.0-8.0 |
Water Parameter Overlap
| Parameter | Common Plecostomus | Swordtail | Overlap |
|---|---|---|---|
| Temperature | 72-86°F | 72-78°F | 6°F ✓ |
| pH | 6.5-7.8 | 7.0-8.0 | 0.8 ✓ |
Compatibility Breakdown
Temperament Match: peaceful + semi-aggressive. Semi-aggressive → watch territory and feeding.
⚠️ Size Predation Risk: Common Plecostomus (15.0") vs Swordtail (5.0"). A 10.0" gap — the larger fish will view the smaller fish as food.
Score: 66.0/100 (GOOD ≥80, CAUTION ≥50, RISKY <50).
🔧 Tank Setup Requirements (for Both)
- Minimum tank: 55 gallons — sized for the larger fish in the pair.
- Temperature: keep it between 72°F and 78°F.
- pH: maintain 7.0 – 7.8.
- Hiding spots: essential for Common Plecostomus — 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 55+ gallons:
Sinking wafers for plecos and bottom feeders
Explore Related Checks
See what else works with these fish:
Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a peaceful individual Common Plecostomus 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.