Fasting tolerance varies by species + age. 3-7 days fasting is safe for: tetras, rasboras, danios, livebearers (guppies, platies, mollies), most barbs, corydoras (3 days max), most community fish. 10-14 days tolerable: oscars + larger cichlids, plecos (with driftwood to graze), goldfish, bettas, koi. They'll be fine for vacation. NEVER fast: fry under 2 weeks (need daily food, multiple times), mandarin dragonets (need constant copepod grazing), saltwater anthias (high metabolism), sensitive marine species. For vacations 7+ days: options: 1) feeder cube (slow-release block) - controversial because they cloud water if full bioload. 2) auto-feeder (Eheim Twin) with pre-portioned daily feedings. 3) ask a friend to feed every 2-3 days (small portions only - overfeeding kills more fish than fasting). For vacations 14+ days: auto-feeder mandatory + ATO + heater on Inkbird controller + email alerts via Apex/Inkbird WiFi. Bonus: a 2-3 day fast monthly is healthy for adult fish - clears digestive system, prevents constipation in bettas + livebearers.
The full Q&A library, calculators, diseases, glossary, and interactive tools answer the most-searched aquarium questions.
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.
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