Fish & Aquariums

Friendly guides to keeping fish well, in the order a real tank comes together: pick a tank big enough, cycle it before any fish arrive, keep the water clean, then choose fish that suit the tank and each other. Pond keepers and would-be saltwater fans are covered too.

A bright planted freshwater aquarium with a school of small tropical fish swimming among green plants and driftwood

Building a Tank From Scratch

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A tank of around 20 gallons (76 liters) or more is more forgiving for a first attempt than a small nano tank. Add a filter rated for the tank, a heater for tropical fish and a liquid test kit, then cycle the tank before buying fish.

Getting Started

Your First Aquarium

What to buy, where to put it and setup day, step by step.

Cycling a Tank

Growing good bacteria before fish arrive, without shortcuts.

Cloudy Water Fixes

Bacterial bloom, debris or algae, sorted with a table.

Tanks and Equipment

Aquariums and Stands

Tank kits by size, rimless and nano tanks, sturdy stands.

Filters and Pumps

Choosing a filter for your tank and fish, and cleaning it safely.

Heaters and Lighting

Adjustable heaters, LED lights, plant lights and timers.

Heater Sizing

How many watts, where to place it, and backup plans.

Substrate and Decor

Gravel, sand, plant soil, driftwood, plants and hides.

Planted and Nano Tanks

Plant substrate, lighting hours and small-tank stocking.

Water, Food and Everyday Care

Water Care and Testing

Conditioners, test kits and a simple water-change routine.

Fish Food

Flakes, pellets, wafers, frozen foods and holiday feeding.

Holiday Care for Fish

Feeders, sitters and preparing the tank.

Moving an Aquarium

Fish, filter bacteria and the tank, moved safely.

Species and Stocking

Community Tropical Tanks

Temperament, swimming level and school size.

Betta Tanks Done Right

Why a bowl falls short, and what a betta needs.

Goldfish Tanks Done Right

Big fish, lots of waste: space and filtration.

Livebearers

Guppies, platies, mollies and endlers, and all those fry.

Corydoras and Catfish

More than a cleanup crew: groups and soft sand.

Freshwater Shrimp and Snails

Copper caution, hardy species and snail numbers.

Angelfish

Adult size, tall tanks and pairs that turn territorial.

African Cichlids

Aggression, stocking and hard rift-lake water.

Tetras and Pencilfish

Small, colorful shoalers that need a crowd.

Rasboras

Calm Asian shoalers, from harlequins to chilis.

Danios and White Clouds

Lively, hardy and often happy unheated.

Guppies

Bright, busy and very good at making babies.

Gouramis

Gentle air-breathers for planted tanks.

Loaches

Playful diggers that need soft sand.

Plecos and Algae Eaters

Bristlenose, otos and the common pleco problem.

Coldwater, Ponds and Saltwater

Garden Pond Basics

Depth, predators, filtration and child safety.

Saltwater Aquariums

Cost, complexity, and why freshwater usually comes first.

Coldwater Tanks

Unheated indoor tanks beyond goldfish.

Frequently Asked Questions

What new aquarium keepers ask most often.

What's the first thing to buy for a new aquarium?

The tank and stand, since everything else fits around them. Around 20 gallons (76 liters) or more is forgiving for a first tank. Then a filter rated for the tank, a heater for tropical fish, a test kit and a water conditioner. Fish come last, after the tank has cycled.

Does tap water need treating?

Yes. Most tap water contains chlorine or chloramine, which harm fish and the bacteria in the filter. Add a water conditioner every time you fill the tank or change water.

Does a small tank need a filter?

Yes. The filter houses the bacteria that break down ammonia and nitrite. A sponge filter or small internal filter suits a nano tank.

How long before I can add fish?

Usually several weeks, until the tank has cycled and tests show ammonia and nitrite back at zero. See cycling a tank.