Aquarium Fish Compatibility Checker

Building a successful community aquarium requires matching fish across several compatibility dimensions. The three most critical factors are temperament, water parameter overlap, and space requirements.

Temperament Scoring: Each fish species is rated on an aggression scale from 1 (peaceful) to 5 (highly aggressive). Compatible pairings should have an aggression difference of no more than 1 point. For example, a Neon Tetra (aggression = 1) pairs well with a Corydoras Catfish (aggression = 1) but poorly with an African Cichlid (aggression = 4).

Compatibility Score = 100 - (Aggression Difference × 20) - pH Penalty - Temp Penalty

Water Parameter Overlap: Fish must share overlapping pH and temperature ranges. The pH penalty is calculated as:

• pH Penalty = max(0, |pH_A - pH_B| - 0.5) × 20

Temperature penalty works similarly:

• Temp Penalty = max(0, |Temp_A - Temp_B| - 2) × 5

Worked Example: Fish A: Neon Tetra (aggression 1, pH 6.5, temp 75°F). Fish B: Guppy (aggression 1, pH 7.2, temp 76°F).

• Aggression difference: 0 → 0 penalty
• pH difference: 0.7 → (0.7 - 0.5) × 20 = 4 penalty
• Temp difference: 1 → no penalty (within 2°F)
• Score = 100 - 0 - 4 - 0 = 96 (Excellent)

Reference: Common Fish Profiles:

Scores above 80 indicate excellent compatibility. Scores between 50 and 80 suggest caution — monitor closely. Below 50 means the pairing is risky and likely to cause stress or aggression.