Can Lawnmower Blenny live with Neon Rainbowfish?
Case-by-case. Watch group sizes, tank size, and feeding zones.
Why Lawnmower Blenny and Neon Rainbowfish Don't Make an Easy Pair
They can coexist, but you need to manage the setup carefully. The temperament combination (peaceful+peaceful) can work, but you will need to watch them at feeding time for the first week.
Lawnmower Blenny
Salarias fasciatus
| Adult Size: | 5.0" |
| Temperament: | peaceful |
| Min Tank: | 30 gal |
| Temperature: | 74-82°F |
| pH Range: | 8.1-8.4 |
Neon Rainbowfish
Melanotaenia praecox
| Adult Size: | 2.5" |
| Temperament: | peaceful |
| Min Tank: | 20 gal |
| Temperature: | 75-82°F |
| pH Range: | 6.5-7.5 |
Water Parameter Overlap
| Parameter | Lawnmower Blenny | Neon Rainbowfish | Overlap |
|---|---|---|---|
| Temperature | 74-82°F | 75-82°F | 7°F ✓ |
| pH | 8.1-8.4 | 6.5-7.5 | No overlap ✗ |
Compatibility Breakdown
Temperament Match: peaceful + peaceful. Both peaceful → minimal conflict.
⚠️ Size Predation Risk: Lawnmower Blenny (5.0") vs Neon Rainbowfish (2.5"). A 2.5" gap — the larger fish will view the smaller fish as food.
Score: 70/100 (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 75°F and 82°F.
- pH: no shared range. One species will be outside its tolerance regardless of what you set.
- Hiding spots: essential for Lawnmower Blenny — 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:
Dried seaweed sheets for marine herbivores
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Accuracy note: This tool uses expert rules + FishBase.org data. Individual fish behavior varies — a peaceful individual Lawnmower Blenny 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.