Compatibility Overview
Congo Tetra and Swordtail 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 | Congo Tetra | Swordtail | Verdict |
|---|---|---|---|
| Temperature | 72–79°F | 65–80°F | ✅ 72–79°F |
| pH Range | 6.0–7.0 | 7.0–8.3 | ⚠️ 7.0–7.0 (narrow) |
| Temperament | aggressive | peaceful | ❌ Risk |
| Adult Size | 1.6 in | 5 in | ⚠️ 3.1× difference |
| Min. Group | 6+ | 3+ | See below |
| Min. Tank Size | 75 gallons (for both species) | — | |
✅ Compatibility Positives
❌ Incompatibility Reasons
Species Profiles
Congo Tetra — Aquarium species
The Congo Tetra is a vibrant and active fish that thrives in a well-maintained freshwater aquarium. With its striking coloration and peaceful nature, it's a great addition to any community tank. This species is best kept in groups and requires a spacious tank with plenty of swimming space. They are known for their playful nature and can be seen darting aroun
Swordtail — Xiphophorus hellerii
Hardy livebearer with a distinctive elongated lower tail fin in males. Peaceful community fish that tolerate a wide temperature range.
Frequently Asked Questions
Can Congo Tetra live with Swordtail?
Generally not recommended. Congo Tetra and Swordtail 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 Congo Tetra and Swordtail together?
A minimum of 75 gallons is recommended for keeping Congo Tetra and Swordtail together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Congo Tetra and Swordtail?
72–79°F
Is a Congo Tetra aggressive toward a Swordtail?
Congo Tetra is aggressive and Swordtail is peaceful. The adult size gap creates a meaningful predation risk.
Related Compatibility Guides
Compatibility score breakdown
The overall score is weighted across water chemistry, behavior, adult size, swimming zone, and social needs. A score is a planning aid—not a guarantee for individual fish.
| Factor | Score |
|---|---|
| Temperature | 100/100 |
| Ph | 0/100 |
| Temperament | 30/100 |
| Adult Size | 38/100 |
| Swim Zone | 68/100 |
| Social Needs | 85/100 |
Tank size scenarios
Use the scenario that matches the actual group sizes and temperament you plan to keep.
| Scenario | Tank | When it applies |
|---|---|---|
| Minimum viable | 75 gal | Only for the recommended minimum groups, mature filtration, and close monitoring. |
| Recommended community | 125 gal | Adds territory, swimming room, and a safer buffer for behavior. |
| Low-conflict setup | 150 gal | Best when keeping larger schools or reducing territorial pressure. |