Beginner aquarium guides
53 guides, in the order a first tank needs them. Each one answers one question and commits to the answer.
Getting Started
Tank size, what a setup costs, and getting it running. 5 guides.
Getting Started10 min
10 Gallon Fish Tank Setup: What to Buy and What It Costs
Getting Started6 min
20 Gallon Fish Tank Setup Cost: Every Item, Priced
Getting Started3 min
How Much Does a Fish Tank Weigh? Every Size, Filled
Getting Started3 min
How to Acclimate Fish to a New Tank (Freshwater)
Getting Started3 min
What Size Aquarium Should a Beginner Get? (Bigger Is Easier)
Equipment
Filters, heaters and substrate, picked from maker specs. 5 guides.
Equipment18 min
Best Aquarium Heater: How Heaters Fail and Which to Buy
Equipment15 min
Best Substrate for a Planted Aquarium: Pick by Your Plants
Equipment8 min
Best Filter for a 10 Gallon Tank: Picks by Setup, With Specs
Equipment9 min
Best Filter for a 20 Gallon Tank: Picks by Setup, With Specs
Equipment6 min
What Temperature Should a Fish Tank Be? By Species
Water & Cycling
The nitrogen cycle, test numbers, and fixing bad water. 7 guides.
Water & Cycling14 min
How to Soften Aquarium Water: Lower GH Without Crashing pH
Water & Cycling10 min
How to Lower Nitrates in a Fish Tank (and Keep Them Down)
Water & Cycling11 min
How to Lower Nitrites in a Fish Tank: What to Do Today
Water & Cycling6 min
Why Do My Fish Keep Dying? Work Out When, Then Why
Water & Cycling4 min
Fish Lying on the Bottom of the Tank: Test the Water First
Water & Cycling4 min
Can You Use Distilled Water in a Fish Tank? Not on Its Own
Water & Cycling3 min
Nitrogen Cycle for Beginners: Why You Wait Weeks for Fish
Fish & Plants
Stocking counts, tank mates, feeding and sick fish. 19 guides.
Fish & Plants13 min
Best Food for Betta Fish: Picks by Size, With Label Data
Fish & Plants14 min
Best Tropical Fish Food: Picks by Where Your Fish Feed
Fish & Plants13 min
Ghost Shrimp Breeding: Eggs, Larvae and Which Ones Need Salt
Fish & Plants9 min
How Many Guppies in a 10 Gallon Tank? Five, All Male
Fish & Plants9 min
How Many Neon Tetras in a 10 Gallon Tank? Eight, and Why
Fish & Plants10 min
Betta Fin Rot: Signs, Treatment, and When to Medicate
Fish & Plants7 min
What Fish Can Live With Goldfish? A Short, Honest List
Fish & Plants4 min
Betta Lying on the Bottom of the Tank: Resting, Cold or Sick?
Fish & Plants5 min
Can a Betta Live With a Goldfish? No, and Here's Why
Fish & Plants4 min
Dropsy in Bettas: The Pine-Cone Sign and What You Can Still Do
Fish & Plants8 min
How Big Do Goldfish Get? Size by Type, Age and Tank
Fish & Plants3 min
How Long Can a Betta Go Without Food? A Week Is Fine, Two Is Not
Fish & Plants3 min
How Long Can Goldfish Go Without Food? Up to Two Weeks
Fish & Plants7 min
How Often to Feed Goldfish: Schedule by Age and Water Temp
Fish & Plants4 min
Swim Bladder Disease in Bettas: Usually Food, Sometimes Not
Fish & Plants2 min
Why Is My Goldfish Turning Black? Check the Ammonia First
Fish & Plants2 min
Why Is My Goldfish Turning White? Age, Light or Water
Fish & Plants4 min
How Many Fish in a 10 Gallon Tank? A Straight Answer
Fish & Plants4 min
Pothos in an Aquarium: Safe for Fish, Risky for Shrimp
Maintenance
Water changes, cleaning, algae, snails and smells. 17 guides.
Maintenance12 min
How to Get Rid of Duckweed in an Aquarium Without Hurting Fish
Maintenance11 min
How to Tell If a Mystery Snail Is Dead: A 3-Step Check
Maintenance4 min
Biofilm in an Aquarium: The Slime You Mostly Want, and the Film You Don't
Maintenance4 min
Black Algae in a Fish Tank: Black Beard Algae and How to Remove It
Maintenance4 min
Blue-Green Algae in an Aquarium: It's Bacteria, and How to Clear It
Maintenance3 min
White Algae in a Fish Tank: What the White Stuff Actually Is
Maintenance7 min
Brown Algae in Fish Tank: Why It Happens and When It Ends
Maintenance4 min
How to Get Rid of Snails in an Aquarium, Without Chemicals
Maintenance3 min
Hydra in an Aquarium: Harmless to Fish, Deadly to Fry
Maintenance3 min
Planaria in an Aquarium: Harmless to Fish, Bad for Shrimp
Maintenance4 min
Worms in a Fish Tank: Which One Is It, and Does It Matter?
Maintenance5 min
How to Change Fish Tank Water, and How Often to Do It
Maintenance5 min
Scuds in an Aquarium: Harmless With Fish, a Problem With Shrimp
Maintenance4 min
Snail Eggs in a Fish Tank: Which Snail, and Will They Hatch?
Maintenance4 min
Why Does My Fish Tank Smell? Match the Smell to the Cause
Maintenance3 min
Detritus Worms in a Fish Tank: Harmless, But Check First
Maintenance3 min
How to Clean Aquarium Decorations Without Killing Fish
What you'll find here
These guides follow the order you actually need them in: choosing a tank and working out what it really costs, the equipment that matters (filter, heater, light, substrate) and what you can skip, the nitrogen cycle and how to run a fishless cycle properly, then stocking (beginner-friendly fish, easy live plants) and the maintenance routine that keeps it all stable.
Every guide is written by a named human author who keeps tanks, gives you the numbers to test against rather than vague advice, and gets updated when better information turns up. Read more about our editorial standards.