Compatibility Overview
Chili Rasbora and Koi 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 | Chili Rasbora | Koi | Verdict |
|---|---|---|---|
| Temperature | 68–82°F | 50–75°F | ✅ 68–75°F |
| pH Range | 4.0–7.0 | 7.0–8.5 | ⚠️ 7.0–7.0 (narrow) |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 0.8 in | 24 in | ❌ 30× difference |
| Min. Group | 8+ | 2+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Chili Rasbora — Boraras brigittae
Vivid red nano fish from Borneo blackwater habitats. Extremely small — only safe with fish too small to swallow them.
→ Full Chili Rasbora care guide
Koi — Cyprinus rubrofuscus
Large pond fish that require hundreds of gallons and cool water. Will eat any fish small enough to fit in their mouth.
Frequently Asked Questions
Can Chili Rasbora live with Koi?
Generally not recommended. Chili Rasbora and Koi 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 Chili Rasbora and Koi together?
A minimum of 100 gallons is recommended for keeping Chili Rasbora and Koi together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Chili Rasbora and Koi?
68–75°F
Is a Chili Rasbora aggressive toward a Koi?
Chili Rasbora is peaceful and Koi is peaceful. Chili Rasbora requires tropical water; Koi requires cold water. These environments are incompatible.