Can Common Plecostomus live with Threadfin Butterflyfish?
These two species are usually compatible in community tanks.
Why Common Plecostomus and Threadfin Butterflyfish Work
These two species overlap in both temperature (74–82°F overlap) and pH (- overlap range). Their temperature tolerances are close enough, and neither fish pushes the pH so far outside the other's comfort zone that it creates chronic stress. The temperament match (peaceful + peaceful) is low-conflict. In a 75+ gallon tank with adequate hiding spots, these two can coexist with minimal problems.
Common Plecostomus
Hypostomus plecostomus
| Adult Size: | 15.0" |
| Temperament: | peaceful |
| Min Tank: | 55 gal |
| Temperature: | 72-86°F |
| pH Range: | 6.5-7.8 |
Threadfin Butterflyfish
Chaetodon auriga
| Adult Size: | 8.0" |
| Temperament: | peaceful |
| Min Tank: | 75 gal |
| Temperature: | 74-82°F |
| pH Range: | 8.1-8.4 |
Water Parameter Overlap
| Parameter | Common Plecostomus | Threadfin Butterflyfish | Overlap |
|---|---|---|---|
| Temperature | 72-86°F | 74-82°F | 8°F ✓ |
| pH | 6.5-7.8 | 8.1-8.4 | No overlap ✗ |
Compatibility Breakdown
Temperament Match: peaceful + peaceful. Both peaceful → minimal conflict.
⚠️ Size Predation Risk: Common Plecostomus (15.0") vs Threadfin Butterflyfish (8.0"). A 7.0" gap — the larger fish will view the smaller fish as food.
⚠️ Diet Conflict: A carnivore sharing water with a fish small enough to fit in its mouth is a waiting game. Feed generously, but the risk is structural — not something you can manage meal by meal.
Score: 80/100 (GOOD ≥80, CAUTION ≥50, RISKY <50).
🔧 Tank Setup Requirements (for Both)
- Minimum tank: 75 gallons — sized for the larger fish in the pair.
- Temperature: keep it between 74°F and 82°F.
- pH: no shared range. One species will be outside its tolerance regardless of what you set.
- 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 75+ gallons:
Frozen mysis shrimp for marine butterflyfish
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.