Bioload
A goldfish and a neon tetra may both be 2 inches but the goldfish produces 3x more waste.
Aquariumstocking.com calculator factors species-specific bioloads.
Swim Levels
Top dwellers: hatchetfish, gouramis, some killifish.
Mid dwellers: most tetras, barbs, guppies, rasboras.
Bottom dwellers: corydoras, plecos, kuhli loaches, shrimp.
A well-stocked tank uses all three levels evenly.
Aggression Compatibility
Peaceful: tetras, rasboras, platies, corys.
Semi-aggressive: barbs, gouramis, angelfish.
Aggressive: most cichlids, large gouramis, bettas.
Never mix peaceful with aggressive species.
Stocking Timeline
Week 6 after cycle: 30% of final stock.
Week 10: 60%.
Week 14: 100%.
Slow stocking lets biological filter catch up.