• Taking care of a saltwater aquarium is a fun and fulfilling hobby for anyone who loves marine life! You’ll start by choosing fish and a sturdy tank, then create your own saltwater to your fishes’ specific needs and get them used to their new environment. Although starting your aquarium can be expensive, the time and financial investment will be worth it when you’ve created a happy, healthy mini-ecosystem.

  • 1
    Decide what fish you want before buying your tank.You won’t buy your fish until your tank is fully set up, but choosing your fish beforehand ensures that you buy the right tank size and accessories. You’ll also decide how many fish you want, whether you want coral or not, and what special parameters you’ll need to set up.
    • Saltwater aquariums can get expensive, so choosing your tank inhabitants beforehand will prevent you from wasting money on an incorrect tank or features.
  • 2
    Choose fish that are hardy and peaceful if you’re a beginner.When you’re just starting, it’s best to choose fish that are tolerant of a fluctuating environment, resistant to parasites, and non-aggressive. You’ll also want fish that are vibrant and fun to look at—and within your budget! You can ask the employees at your local pet store for recommendations. Some species to consider include:
    • Clownfish
    • Cardinalfish
    • Firefish
    • Royal Grammas
    • Swissguard Basslets
  • 3
    Avoid common saltwater fish that are too sensitive or aggressive.Some species of saltwater fish are often recommended for beginner tanks, but you should purchase them with care. Avoid any fish that are picky eaters, classified as aggressive or semi-aggressive, or are sensitive to environment fluctuation. Fish to avoid include:
    • Mandarinfish, which are picky eaters
    • Bluestreak Cleaner Wrasse, which are picky eaters
    • Groupers, which are very aggressive
    • Damselfish, which are aggressive and territorial
    • Mollies and guppies
  • 4
    Choose a short, wide tank.Tanks that are short and wide, as opposed to tall, allow good oxygen flow within the water, better light penetration, and easier cleaning. Your fish will enjoy the extra horizontal swimming space, and you can get more creative with your aquascaping to give them more nooks and niches to explore.
    • If you have to go with a tall, narrow tank for space reasons, use powerful circulation tools to move water throughout the tank and encourage oxygenation.
  • 5
    Buy a tank large enough for your fully-grown fish.Look online to figure out how large your fish species will grow in captivity. Then, add up the length and width measurements of your tank and divide them by the fish’s size. The answer should be greater than 4, but larger than 6 is preferable.
    • For example, if your fish grows to be 21 inches (53 cm) in captivity and your tank is 3 by 6 feet (0.91 by 1.83 m) long, you’d divide 108 inches (270 cm) by 21 inches (53 cm) to get 5.1. This tank would be big enough.
    • As a rule of thumb for how many fish your saltwater aquarium can hold, estimate that you can have 3 inches (7.6 cm) of fish for every square foot (0.3 m) of surface area.
  • 6
    Go for a bigger tank when you’re in doubt.A larger tank gives you a greater margin of error in case you make a mistake—there will be more water to dilute possible pollutants, for example. You’ll also have fewer fish interaction problems and a more stable overall system.
    • You’ll have room for more aquascaping as well, with additions like rocks and plants.
    • Many aquarium owners who start off with a small tank will soon upgrade to a larger one, resulting in more set-up work and financial investment.
  • 7
    Buy a submersible heater of 3-5 watts per gallon.This should be a minimum size—for a larger tank, you may want a bigger heater. When you place it in the tank, you’ll want to keep the water at 72 to 82 °F (22 to 28 °C), depending on your fish.
    • Saltwater fish are very sensitive to temperature change, so it’s important to keep your tank’s water at a constant temperature.
  • 8
    Purchase a filter to keep your water clean.Look for a filtration system made for saltwater aquariums. Ask a salesperson what size you should get for your chosen tank, and purchase in a store or online for convenience.
    • Don’t set up your filter just yet. You’ll install it once you’ve filled your tank.
    • Filters can also be called powerheads.
  • 9
    Choose aquarium lighting that’s suitable for your saltwater fish.Buy an aquarium lighting system in a pet store or online and set it to illuminate your aquarium for 8-10 hours a day. Look up what light spectrum you’ll need for your desired fish, or ask a pet store employee for a recommendation.
    • Many aquarium lights come with built in timers to turn on and off automatically.