Aquarium Guides
Practical, evergreen guides on cycling, water chemistry, filters, stocking math, and beginner plants. New guides added regularly.
Best Beginner Community FishEasy-care, peaceful species suited to a 20-gallon-or-smaller community tank.The Nitrogen Cycle: How to Cycle a New AquariumAmmonia, nitrite, nitrate — what they are, how to fishless-cycle, and how to know when your tank is ready for fish.Why Do My Fish Die After a Water Change?The five things that kill fish during water changes — chlorine, temperature, pH, old tank syndrome, and gas — and how to prevent each.Aquarium Filter Sizing: How Many GPH Do You Need?How to pick the right filter size for your tank, why the '4× turnover' rule is misleading, and which filter style suits each setup.Hard Water vs. Soft Water Fish: How to Match Species to Your TapGH and KH explained, why they matter more than pH, and which freshwater species thrive in each water type.The 1-Inch-Per-Gallon Rule (and Why It's Wrong)Why the most-repeated stocking rule in the hobby is misleading, and what to look at instead.The 8 Easiest Aquarium Plants for BeginnersEight live plants that thrive in low light, need no CO₂, and forgive beginner mistakes.