How to Start a Fresh Water Tank

Select your desired aquarium, choosing a tank of the size and material that work best for you. Acrylic tanks are clearer and more flexible than glass ones, but are more expensive and scratch more easily. Opt for the largest tank your space and budget can afford, as larger aquariums tend to be more stable than smaller ones. A 20-gallon tank is a good option for first-timers.

Choose your filtration, heating and lighting systems. Any tank larger than a fishbowl requires a heater and an overhead full-spectrum light. Under-gravel filtration systems assist with biological filtration and are highly recommended, especially when used in combination with a mechanical filtration system such as a power filter. Consult your local aquarium supplier for detailed information about filtration options.

Rinse your under-gravel filtration system with warm water and place it along the bottom of the tank.

Rinse your gravel with warm water and lay it atop the under-gravel filter at the bottom of your aquarium. Add approximately 1 to 1.5 pounds of gravel per gallon of tank capacity.

Fill the tank 3/4 of the way to the top with tap water.

Add live plants and decorations, rooting all plants deeply in the gravel.

Place your chosen mechanical filtration system. Fill the tank the rest of the way to the top and turn on the filter.

Install your heater and overhead light. Wait 15 minutes to allow the heater's internal thermostat to adjust to the water temperature before plugging in the heater and light.

Add anti-chlorine solution according to the directions on the bottle.

Let the aquarium run for at least a full day before adding fish. This is essential for water conditions to stabilize. Use your aquarium test kit to monitor nitrogen and ammonia levels and to confirm they are within the acceptable ranges described in your test kit's instruction booklet.

Add your first small group of two or three fish. They should come in a plastic bag. Allow this bag to float on the surface of your aquarium for at least five minutes to acclimate the fish to its temperature. Then, add some water from the aquarium to the bag, close it again and wait for at least another 10 minutes. Finally, open the bag and allow the fish to enter the aquarium directly.

Add additional fish to the aquarium in small groups of five or fewer. Allow up to a week for each new group of fish to become acclimated before adding more. Use your test kit to check ammonia and nitrogen levels before adding new groups. Do not overcrowd your aquarium; plan to have approximately 1 inch of fish for each gallon of water.