Can Goldfish live with Upside-Down Catfish?
High risk due to water mismatch, aggression, or predation.
Why Goldfish and Upside-Down Catfish Don't Make an Easy Pair
The size gap is 6.5" — Goldfish (10.0") and Upside-Down Catfish (3.5"). A fish that fits in another fish's mouth will eventually end up there.
Goldfish
Carassius auratus
| Adult Size: | 10.0" |
| Temperament: | peaceful |
| Min Tank: | 30 gal |
| Temperature: | 62-74°F |
| pH Range: | 6.5-7.5 |
Upside-Down Catfish
Synodontis nigriventris
| Adult Size: | 3.5" |
| Temperament: | peaceful |
| Min Tank: | 30 gal |
| Temperature: | 72-82°F |
| pH Range: | 6.0-7.5 |
Water Parameter Overlap
| Parameter | Goldfish | Upside-Down Catfish | Overlap |
|---|---|---|---|
| Temperature | 62-74°F | 72-82°F | 2°F ✓ |
| pH | 6.5-7.5 | 6.0-7.5 | 1.0 ✓ |
Compatibility Breakdown
Temperament Match: peaceful + peaceful. Both peaceful → minimal conflict.
⚠️ Size Predation Risk: Goldfish (10.0") vs Upside-Down Catfish (3.5"). A 6.5" gap — the larger fish will view the smaller fish as food.
Score: 40.0/100 (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 74°F.
- pH: maintain 6.5 – 7.5.
- Hiding spots: essential for Goldfish — 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 2°F of overlap means a stuck heater or seasonal temperature swing can push one species out of its comfort zone.
- Size-based predation: The 6.5" 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 Goldfish 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.