Compatibility Overview
Goldfish and Otocinclus are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
| Factor | Goldfish | Otocinclus | Verdict |
|---|---|---|---|
| Temperature | 50–74°F | 72–82°F | ⚠️ 72–74°F (narrow) |
| pH Range | 6.5–8.0 | 6.0–7.5 | ✅ 6.5–7.5 |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 12 in | 1.5 in | ❌ 8× difference |
| Min. Group | 1+ | 4+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Goldfish — Carassius auratus
Classic pond and aquarium fish that prefer cool water. Heavy waste producers that require robust filtration. Will eat small fish and shrimp.
Otocinclus — Otocinclus spp.
Tiny algae-eating catfish that are peaceful with all species. Need established algae growth and biofilm; sensitive to ammonia.
Frequently Asked Questions
Can Goldfish live with Otocinclus?
Generally not recommended. Goldfish and Otocinclus are generally not recommended to be housed together. The issues listed above — whether water parameter incompatibility, predation risk, or aggression — create conditions where one or both fish are likely to suffer harm or chronic stress.
What tank size do I need for Goldfish and Otocinclus together?
A minimum of 100 gallons is recommended for keeping Goldfish and Otocinclus together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Goldfish and Otocinclus?
72–74°F (narrow)
Is a Goldfish aggressive toward a Otocinclus?
Goldfish is peaceful and Otocinclus is peaceful. Goldfish requires cold water; Otocinclus requires tropical water. These environments are incompatible.