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7 Freshwater Aquarium Essentials

Fish tanks grace a vast number of U.S. homes and doctors’ offices for several reasons: fish are quiet, colorful, inexpensive, and they don’t leave stinky lumps sitting in a box for you to scoop up. But contrary to the popular minimalist image of a sole goldfish swimming in a bowl, keeping fish as pets demands a lot of forethought, diligence, and upkeep. You’ll need several supplies to create a safe environment where freshwater fish will not only survive but thrive. Taking the tank itself as a given, the following list outlines some of the most necessary equipment to prep the water for your new aquatic arrivals.


Starting from the bottom, it's recommended to have some kind of substrate for aesthetic purposes and support beneficial bacteria that break down fish waste. The substrate also provides a more familiar, natural-looking environment for fish to adapt to. Which type of substrate you should use depends on the fish, but in the case of freshwater tanks, gravel is incredibly common. The habits of the fish should determine the gravel's coarseness or fineness you plan to own. For example, if you have any bottom-dwelling fish that likes to interact with the substrate material, you wouldn't want them to get injured by jagged edges. (Just remember that waste clings to substrate. A gravel vacuum to remove the tiny particles without upsetting the gravel itself.) Substrates are also must-haves if you want to install live plants, which need to latch onto something to absorb nutrients.

Water Conditioner

If you’re using tap water to fill or top off your tank, you’ll have to first rid it of chlorine and chloramine—chemicals that make such water safe for human consumption but wreak havoc on fish (i.e., they’ll die). An easy and effective way to combat these dangerous chemicals is through a water conditioner, specifically a complete conditioner that targets chlorine, ammonia, heavy metals—and even has the bonus perk of supporting the protective slime coats of your fish.


Three main filtration types—mechanical, biological, and chemical—are used to fight different water contamination forms. Mechanical filtration essentially moves water through a strainer that collects physical debris, so you, the owner, can then discard it. Biological filtration supplies the water with beneficial bacteria that gradually converts the harmful ammonia by-products into less harmful nitrates. And chemical filtration, usually in the form of activated carbon, absorbs the dissolved impurities mechanical filters can’t. Thankfully some filters can take on all these tasks, but you’ll want one that’s appropriate to your tank.

Test Kits

You may feel like you’re doing enough to keep the water clean and safe, but to know for sure, you'll need a test kit, which measures the potentially harmful pH and nitrate levels unseen by the naked eye. It's suggested you test water quality every two to three days, which may sound a little tedious, but the upside is you can indulge your inner scientist. The most convenient way to perform these tests is through a Master Test Kit, which provides the testing solutions you need to determine the levels of ammonia, nitrites, nitrates, pH, etc. The tests are pretty basic: place a sample of aquarium water in a beaker, sprinkle in the testing solution, and the mixture will turn a specific color. Then compare that color with the kit’s color card that indicates chemical concentration level and associated danger, so you'll know if it’s time for a cleaning.


Whether you’re more traditional or you’d rather be reminded of a discotheque, aquarium lights are an excellent way to adorn your setup with a creative flourish. But aside from being an aesthetic touch and a way to better view your pets, lights significantly impact the well-being of your fish and any live plants within your tank. Plants need light to undergo photosynthesis and produce oxygen and do all the other things that make them beneficial organisms for your fish. There are many factors that go into determining what type of light, and how much, is best for the particular fish in your tank.

Thermometer (+Heater/Chiller)

Fish need their water temperature to be just right. So first, you have to know what the water temperature is. From digital to adhesive to probes to floating thermometers, there’s seemingly endless variety here. But take a look at the different options and make an informed decision (remember the more accurate, the better). The target temperature directly relates to the type of fish (e.g., tropical ones need a bit more heat). Your lights will serve as a heat source to a certain extent, but to make bigger water temp changes, you'll have to add a heater or chiller to your supply bag.

Tank Cover

All sorts of perils can befall an uncovered fish tank. Anything from wobbly lamps to poorly placed soccer trophies can spell disaster. There’s also the constant threat of microscopic debris floating down from all corners and contaminating the water. Not only do tank covers keep harmful agents out, but they also keep your more daring fish from escaping. And the water itself will also escape (through evaporation) if left uncovered. Standard cover (or hood) materials are glass, plastic, and wood, with designs ranging from basic to snazzier versions with built-in lights.


A fish tank is a small indoor ecosystem, so it’s no surprise that the hobbies of fishkeeping—with its routine tests, temperature checks, and bacterial goings-on—can feel like an ongoing science experiment. You have to strike a delicate balance between the natural and the mechanical. The type of supplies you purchase will be informed by the kind of fish you'll be taking under your care, so be sure to do your research and understand their individual needs first. But all that groundwork can lead to one satisfying and harmonious result.

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