Aquarium Fish Compatibility Calculator
Created by: Ethan Brooks
Last updated:
Check fish compatibility before adding new species to your aquarium. This calculator analyzes temperament, water parameter requirements, tank size needs, and potential conflicts to help you build a harmonious community tank.
Aquarium Fish Compatibility Calculator
AquariumCheck if different fish species can coexist peacefully in your aquarium
Related Calculators
What is an Aquarium Fish Compatibility Calculator?
An Aquarium Fish Compatibility Calculator helps determine whether different fish species can coexist peacefully in the same tank. It analyzes temperament, water parameter requirements, size considerations, and behavioral patterns to predict compatibility.
This tool prevents common mistakes like mixing aggressive with peaceful species, combining fish with incompatible water needs, or creating stressful environments that lead to disease and death. Proper compatibility planning is essential for a thriving community aquarium.
Key Compatibility Factors
Temperament Match: Peaceful fish with peaceful, semi-aggressive with semi-aggressive. Mixing aggression levels causes stress and casualties.
Water Parameters: pH, temperature, and hardness must overlap for all species. A fish needing pH 6.5 cannot thrive with one needing pH 8.0.
Size Compatibility: General rule: if a fish can fit in another's mouth, it will become food. Keep similar-sized fish together.
Swimming Levels: Mix top, middle, and bottom dwellers to reduce competition and territorial disputes.
Frequently Asked Questions
What makes fish compatible or incompatible?
Fish compatibility depends on: temperament (aggressive vs peaceful), water parameters (pH, temperature, hardness), size differences (large fish may eat small ones), swimming level preferences (top, middle, bottom dwellers), diet requirements, and territorial behavior. Species from similar habitats often work well together.
Can I keep aggressive and peaceful fish together?
Generally no. Aggressive fish stress, injure, or kill peaceful species. However, some semi-aggressive fish can work in larger tanks with careful species selection, adequate hiding spots, and appropriate tank mates that can hold their own without being targets.
Why do fish fight even if they're the same species?
Same-species aggression occurs due to territorial disputes, mating competition, or inadequate group sizes. Many species need specific ratios (like 1 male to 3 females for livebearers) or group sizes (schooling fish need 6+). Insufficient space also triggers aggression.
Can freshwater and saltwater fish live together?
No. Freshwater and saltwater fish have completely different physiological adaptations and cannot survive in the other's environment. Brackish fish require specific salinity levels between fresh and saltwater, and shouldn't be mixed with either extreme.
How do I introduce new fish to avoid aggression?
Rearrange decorations before adding new fish to disrupt established territories. Add new fish with lights off, ideally in the evening. Quarantine new fish first. Add multiple fish at once rather than one at a time. Have backup plans if aggression occurs.
What fish can live with bettas?
Male bettas can live with peaceful bottom-dwellers (corydoras, kuhli loaches), small schooling fish (ember tetras, harlequin rasboras), and snails/shrimp in 10+ gallon tanks. Avoid fin-nippers, bright-colored fish, other bettas, and anything that may trigger territorial aggression.
Can I keep African cichlids with South American cichlids?
Generally not recommended. African cichlids prefer hard, alkaline water (pH 7.8-8.6) while most South American cichlids need soft, acidic water (pH 6.0-7.0). Their aggression styles also differ. Mixing usually results in stress, disease, and deaths.
How important is swimming level compatibility?
Very important for reducing stress and competition. Combining top-dwellers (hatchetfish), mid-dwellers (tetras), and bottom-dwellers (corydoras) creates a balanced tank where each species has its own space, reducing territorial conflicts and stress.
Sources and References
- Seriously Fish, "Species Compatibility Database", 2024
- Aquarium Co-Op, "Community Tank Stocking Guide", 2024
- FishBase, "Species Ecology and Behavior Data", 2024