Dose Seachem Prime which detoxifies ammonia for 24-48 hours. Verify temperature + pH. Identify if ammonia or nitrite spiked.
Drop ammonia + nitrite via dilution. Match temperature + pH of replacement water. Use Prime in new water.
For the next 2 weeks: 25% daily water change with Prime. Test daily. Bacteria will catch up; fish survive if you can keep parameters detoxified.
Less food = less waste = less ammonia. Fish can survive a week without food in the cycling phase.
Dose Bio-Spira or Stability daily for 7-14 days. Speeds bacterial colonization to take pressure off fish.
Fishless cycling with pure ammonia + bottled bacteria is humane + faster + cheaper. Don't repeat this mistake.
Browse all cycling troubleshooting articles. Pair with the cycle ETA calculator + fishless cycle ammonia calculator.
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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