Betta cohabitation is one of the most-debated aquarium topics. The safe answer: most bettas thrive solo. Multiple males - never: male Betta splendens will fight to the death in any tank size, no exception. Even sight of another male through dividers triggers chronic stress. Female sorority (advanced setup only): 5+ females in a heavily-planted 20-gallon long minimum. Smaller groups cause one fish to be bullied to death. Introduce all females simultaneously, never add to existing group. Each female needs her own territory + escape route + multiple sight breaks. Even successful sororities can fail without warning. Failure rate: 30-50%. Male + female (breeding setup only): separate tanks normally; combined briefly in a 10g+ breeding tank with hides. Female removed after spawn. Never permanent cohabitation. Wild bettas (B. imbellis, B. smaragdina, B. mahachaiensis): some species can be kept in pairs/trios with extreme caution + huge tanks. Not for beginners. Splendens with other species: peaceful tankmates only - corydoras (larger species), kuhli loaches, ember tetras, snails, shrimp (50/50 - some bettas eat shrimp). Avoid: fin nippers (tiger barbs, serpae tetras), aggressive fish, brightly-colored males the betta sees as rivals. Recommendation: 1 male betta in a 5g+ planted tank with snails + perhaps 5-10 amano shrimp. Most peaceful long-term setup.
The full Q&A library answers the most-searched aquarium questions. Browse calculators, glossary, and disease database for related help.
Whatever specific topic brought you here, four fundamentals govern long-term aquarium success: water quality, parameter stability, biological filtration, and species-appropriate husbandry. Skip any one and the others struggle to compensate.
Water quality: ammonia + nitrite at zero, nitrate under 30 ppm freshwater + 10 ppm reef. Test weekly with API or Salifert kits. Use our water parameter checker to score your readings against your tank type.
Parameter stability: stable wrong parameters beat fluctuating ideal parameters. Most fish tolerate a wide pH range if it's stable. Sudden swings of 0.4+ pH or 5+°F kill fish faster than chronic suboptimal values. Use temperature controllers (Inkbird) + automated dosing for consistency.
Biological filtration: the bacterial colony on your filter media + rock + substrate is the engine. Never replace all media at once. Use our filter turnover calculator to size correctly.
Species-appropriate husbandry: research adult size, territoriality, diet, and tankmate compatibility before purchase. Use our tank stocking calculator + compatibility guides.
How long does an aquarium take to set up? 4-6 weeks for full cycling + first stocking. Use our cycle ETA calculator + how long does cycling take.
What's the best aquarium for beginners? 20-gallon long. Big enough for parameter stability, small enough for budget + space. See beginner picks.
How often should I do water changes? 25-30% weekly. See water change frequency Q&A + water change calculator.
Why does my fish keep dying? 5 leading causes: uncycled tank, wrong species pairings, no quarantine, undersized tank, neglected water-change schedule. See full diagnosis.
Saltwater livestock · Freshwater livestock · Coral catalog · Care library · Q&A library (222) · Glossary (127) · Disease database (50) · Calculators (29) · Interactive tools (7) · Husbandry deep-dives · DIY projects · State legality directory