Can Emperor Tetra live with Goldfish?
High risk due to water mismatch, aggression, or predation.
Why Emperor Tetra and Goldfish Don't Make an Easy Pair
The size gap is 8.0" — Emperor Tetra (2.0") and Goldfish (10.0"). A fish that fits in another fish's mouth will eventually end up there.
Emperor Tetra
Nematobrycon palmeri
| Adult Size: | 2.0" |
| Temperament: | peaceful |
| Min Tank: | 20 gal |
| Temperature: | 73-82°F |
| pH Range: | 5.5-7.0 |
Goldfish
Carassius auratus
| Adult Size: | 10.0" |
| Temperament: | peaceful |
| Min Tank: | 30 gal |
| Temperature: | 62-74°F |
| pH Range: | 6.5-7.5 |
Water Parameter Overlap
| Parameter | Emperor Tetra | Goldfish | Overlap |
|---|---|---|---|
| Temperature | 73-82°F | 62-74°F | 1°F ✓ |
| pH | 5.5-7.0 | 6.5-7.5 | 0.5 ✓ |
Compatibility Breakdown
Temperament Match: peaceful + peaceful. Both peaceful → minimal conflict.
⚠️ Size Predation Risk: Emperor Tetra (2.0") vs Goldfish (10.0"). A 8.0" gap — the larger fish will view the smaller fish as food.
Score: 20.0/100 (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 74°F.
- pH: maintain 6.5 – 7.0.
- Hiding spots: essential for Emperor Tetra — 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:
Goldfish-specific flake food
Explore Related Checks
See what else works with these fish:
⚠️ Common Reasons This Pairing Fails in Practice
- Narrow temperature margin: Only 1°F of overlap means a stuck heater or seasonal temperature swing can push one species out of its comfort zone.
- Size-based predation: The 8.0" 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.
- 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 peaceful individual Emperor Tetra 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.