Aquarium Stocking Density
Sustainable fish count per gallon by species with aggression / territory adjustments.
Gear actually worth buying
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Glass aquarium tankeBay has a solid secondhand market for tanks. Check for scratches and check the seals before committing.
Canister filterCanister filters (Fluval, Eheim, SunSun) outperform HOB filters for tanks 40 gallons and up.
Full-spectrum aquarium LED lightPlanted tanks need PAR, not just brightness. Fluval Plant 3.0 and Chihiros are the known-good options.
Aquarium substrate / gravelInert gravel is fine for fish-only. Planted tanks need nutrient-rich substrate (Fluval Stratum, ADA).
Heater + thermometerCobalt Aquatics and Eheim heaters hold temperature steadily. Avoid no-brand heaters — they cook fish.