Aquarium Guides
Practical, specific guides to setting up and stocking a freshwater tank — grounded in the 123 species in our database.
How to Cycle an Aquarium
The nitrogen cycle, fishless cycling, and how to tell when a tank is ready for fish.
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Aquarium Water Parameters
Which numbers to test, what the targets are, and how to pick fish that suit the water you already have.
11 min read Stocking GuideHow Many Fish in a Tank?
Why the inch-per-gallon rule fails, and what to use instead when planning a stocking list.
10 min read Stocking Guide20 Gallon Stocking Ideas
Seven full stocking lists for a 20 gallon (76 L) tank, with exact numbers and why each one works.
10 min read MaintenanceAquarium Algae Control
Identify the algae you have, fix the cause, and pick the cleanup crew that eats that particular type.
9 min read CompatibilityChoosing Tank Mates
The five checks that decide whether two species can share a tank — in the order that matters.
9 min read Stocking Guide5 Gallon Tank Stocking
Honest options for a 5 gallon (19 L) nano tank, and the popular choices that don't belong in one.
8 min read Species Guide15 Best Fish for Beginners
Hardy, forgiving species that survive the mistakes every first-time fishkeeper makes.
12 min read Stocking Guide10 Gallon Tank Stocking Ideas
Eight complete combinations for a 10 gallon (38 L) tank, with exact numbers.
9 min readNeed help choosing fish?
Answer a few questions about your tank and we'll suggest species that fit it.
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