Start with the adult fish
Choose the species before buying the tank. Check adult size, swimming space, group size, and the water available from your tap. A small fish is not automatically suited to a small aquarium. Use our aquarium finder to screen the reviewed species.
Prepare the equipment
You need a suitable aquarium and stable stand, a lid where appropriate, filtration, a thermometer, water conditioner, and water tests. Tropical species may need a heater. Add hiding places and leave swimming room. Keep aquarium equipment separate from household cleaners.
Establish biological filtration
Fish waste produces ammonia. A functioning biological filter helps process it into nitrite and then nitrate. Prepare the system before adding livestock; follow a fishless-cycling method with an aquarium ammonia source and repeated water tests. Time alone does not prove that a filter can handle waste.
Add fish gradually
Confirm that the filter processes the intended waste input and that ammonia and nitrite test at zero. Introduce livestock gradually, watch behavior, and keep testing after additions. Record water changes so you can adjust maintenance to the tank rather than a fixed calendar.