Compatibility Overview
Koi and Pea Puffer 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 | Koi | Pea Puffer | Verdict |
|---|---|---|---|
| Temperature | 50–75°F | 74–82°F | ⚠️ 74–75°F (narrow) |
| pH Range | 7.0–8.5 | 7.0–8.0 | ✅ 7.0–8.0 |
| Temperament | peaceful | semi | ⚠️ Monitor |
| Adult Size | 24 in | 1 in | ❌ 24× difference |
| Min. Group | 2+ | 1+ | See below |
| Min. Tank Size | 100 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
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.
Pea Puffer — Carinotetraodon travancoricus
World's smallest pufferfish — intensely territorial and nippy despite tiny size. Will attack fins and eat shrimp and snails.
Frequently Asked Questions
Can Koi live with Pea Puffer?
Generally not recommended. Koi and Pea Puffer 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 Koi and Pea Puffer together?
A minimum of 100 gallons is recommended for keeping Koi and Pea Puffer together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Koi and Pea Puffer?
74–75°F (narrow)
Is a Koi aggressive toward a Pea Puffer?
Koi is peaceful and Pea Puffer is semi. Koi requires cold water; Pea Puffer requires tropical water. These environments are incompatible.