GUIDE TO SETTING UP AN AQUARIUM (FRESHWATER)


by Pearl A.

Most pets breathe the same air and live in similar conditions as we do, so making them comfortable is simple. Aquarium fish, widely misunderstood as “easy” pets, actually require us to create a livable habitat, almost from scratch. There’s a reason keeping fish is a “hobby” and not just owning another pet!

Keeping a freshwater aquarium is not difficult, but you should expect to spend some time and care on your fish – most of it right up front. Once a healthy fish tank is set up, care for fish becomes largely a matter of keeping good habits, and a beautiful aquarium can easily take up less of your time than other pets.

We want you be successful with your freshwater aquarium! This is a guide to getting started. (Use the links below to skip ahead, or as a quick reference checklist.)

Planning Essential Equipment for Setup Setting Up Cycling Your Aquarium Adding Fish



PLANNING


Most failures and unforeseen expenses encountered by first-time fish keepers can be avoided with a little foresight. Take some time to plan your first setup – it’s fun!

Location

It’s best to pick a permanent location – a gallon of water weighs a little over 8 lbs; with substrate a 10 gallon tank can weigh over 100 lbs. Leave wiggle room behind the tank for equipment and cables and ensure you can access everything for maintenance.

The surface that supports your tank must be level and very sturdy. Larger tanks may need special furniture – stands can be purchased or built; be certain of the quality of construction! Here are some other things to keep in mind:

Tank Size betta bowl

Very small bowls or tanks from a half gallon to 5 gallons in size are limited in use. The smallest of these are only suitable for bettas; larger tiny tanks can accommodate other tiny species. (Goldfish actually need quite a bit of room and can outgrow a 10 gallon tank quickly.) If you want to keep a betta bowl, get the largest small bowl you can!

5 gallon fish tank Small “desktop” aquariums of 5-10 gallons are limited as well; even so, they are popular with beginners who want to start small. Just be mindful of the adult size of the fish you want to keep, and resist the temptation to overstock!

Ideally, start with a fish tank somewhere between small and large – between 20 and 55 gallons for a freshwater tank gives you a good range of options, without being too demanding in terms of maintenance. More water volume means changes happen slowly, since there is more water to “buffer” or absorb the shock – much more forgiving for the beginner.

Some tanks are “tall” (or “long”) and some are “wide”. Tall tanks are narrow; they are attractive to look at but they offer less surface area than wider, lower tanks. Surface area - the surface of your water - is where gas exchange occurs; where oxygen enters your water and waste gases escape. In a tall tank where there is less water exposed at the surface, you may need additional equipment to make sure enough oxygen is getting into your system (fish, like all animals, need oxygen to live).

Stocking Discus

A common formula tells you to provide a gallon of water per inch of fish you want to keep (this refers to the adult size of the fish). This formula does not always apply. Fish the same length differ in mass – larger fish need more water. Some fish produce the same amount of waste as several other fish their size. Still others are adapted to swimming very fast for long distances, or are territorial and can turn aggressive if there isn’t enough space for them to feel comfortable sharing.

Planning your livestock is wise. It’s easy to find information on common freshwater species – there are many books and online resources available. If you’re interested in live plants, plan them too. They need different levels of light and care. Some fishes will vigorously uproot anything you plant, so you may need to make a choice!

We recommend that beginners stick to peaceful fish and combinations of fish that will get along. “Hardy” (disease and change resistant) species are also a good choice. Goldfish are cold water fish but most freshwater species are tropical, so you can’t keep them in the same tank. Most freshwater fish can adapt to a range of pH levels as long as they are slowly acclimated; as a beginner you may wish to avoid those with very specific pH needs.

Freshwater fish in general can adapt to the pH of your tap water more easily than you can change the pH (and maintain the change). It is sensible to buy a pH test kit during the planning stages and test your tap water to find out what you’re working with - then plan to stock fish that can live comfortably at that level.

Here are stocking recommendations for a few common freshwater aquarium species (remember that small tanks need frequent cleaning to maintain good conditions):

Species Minimum Tank Size How Many Adult Length
Cherry Barb 5 gallons 5-6 (schooling fish*) 1.5-2"
Sparkling Gourami 5 gallons 2-3 1.5"
Neon Tetra 10 gallons 6 (schooling fish*) 1.5"
Guppy 10 gallons 3-4 2"
Goldfish 20 gallons (yes, 20!**) 1-2 12"-2 feet
Angelfish 29 gallons (tall is better b/c fin size) 2 6"
Discus 40 gallons (depth min. 18") 4 6-8" round
Oscar 55 gallons 2 13"


*Schooling fish display fuller colors and better behavior when kept in groups of 6 or more. Their schooling - darting back and forth together as a group - is beautiful to watch!
**Goldfish are notoriously dirty; for additional fish provide 10 gallons each.

Patience!

The truth is that if you want and expect to keep your fishes for a good long time – most live for years with proper care – you are going to have to get used to the idea that a healthy aquarium can’t be rushed. Take it step by step and accept that it’s just part of the process – planning will ease the frustration of waiting and heighten your anticipation!
ESSENTIAL EQUIPMENT FOR SETUP


Once you know your tank size, pick up the equipment you need to get it up and running.

Aquarium Filters filter

Aquarium filters suggest a tank size or tell you a GPH for each model. GPH, or gallons per hour, is the flow rate of water pumped through the filter. Most freshwater tanks need to be “turned over” 4x an hour - multiply the total volume of your tank by 4 for the minimum GPH you will need. Then adjust upward from that – buy the second or third higher model from the rating that fits your tank.



Aquarium Lighting lighting

Freshwater aquarium lights ideally are Kelvin rated between 5500-6700K – this spectrum is a little warmer than that used for marine lighting, and promotes live plant growth. (Anything lower will give you algae problems.) Even without live plants, it will show off fake plants and freshwater fish to their best appearance.

If you bought an aquarium kit, it probably came with a light fixture. If you're buying a light fixture separately, make sure it will fit your tank or canopy. And do buy a hood or canopy! Many fish will jump out of your tank if you don’t have one, and glass canopies especially will cut down on evaporation. For detailed information on the types of bulbs and lighting available, see our full length article on choosing aquarium lighting.

Heater & Thermometeraquarium heater

Aside from goldfish, most aquarium fish are from tropical climates - which means they are used to warmth and stable temperatures (large bodies of water take a long time to cool down or warm up). You will need an aquarium heater - and an aquarium thermometer to make sure your heater is working. They are inexpensive and critical to maintaining steady tropical warmth year round. Even if you live in a tropical zone, shifts in temperature that can occur from day to night are dangerous to fish. Even bettas will live longer and healthier with a heater. Many hobbyists choose to use two less powerful heaters for more even heating and backup in case of problems.

Aquarium Substrates  gravel

If you want live plants, it’s worth it to spend more on a plant substrate. Otherwise, look for “inert” substrates that will not affect your pH or alkalinity. Sand and gravel are nicer to look at than a bare, dirty tank floor - they also provide surface area for beneficial bacteria to colonize. Use only substrates that are aquarium safe.

Aquarium sand is good if you plan to keep bottom dwellers that might be damaged by rough gravel. But stay away from fine sands unless you plan to keep burrowers; otherwise it will compact to form “anaerobic” zones where a lack of oxygen allows dangerous chemicals to form. Beyond this, substrate choice is largely aesthetic.

For most tanks you’ll want about a pound of substrate/gallon; if planting, build up about 2-3 inches on your tank floor. If you can add a handful of sand or gravel from a healthy, established tank, it will speed up the “cycling” process (more on this later).

Decorations and Backgrounds decor

Real or fake aquarium plants and decorative caves or tunnels relieve fish stress by making them feel safer. Give them places to hide! Decorations should be non-toxic and aquarium safe.

Air stones are popular for their dynamic appearance; they also stir up the water a little to promote gas exchange. (An air pump is a smart investment, but I’ve left it off the essential equipment list since it is possible for a filter to provide adequate aeration. The more fish you want or the larger your tank is, the more likely it is you need an air pump - and plants take up oxygen at night, so it's wise to have one for a planted tank too.)

Aquarium backgrounds hide cables and equipment behind your tank. They also create an illusion of greater depth. There are many choices, and even a plain blue or black background looks great – you can even paint the back of your tank for a similar effect (on the outside, of course).

Water Conditioner conditioners

Tap water contains heavy metals from the piping it runs through, and chlorine or chloramine to kill bacteria. These are harmful to your aquarium, so you need to condition tap water before filling, changing or replacing water in your tank.

A good water conditioner neutralizes chlorine and heavy metals and “ages” the water to make it less of a shock to your fishes’ delicate system. Many stress relievers condition your water, with the added bonus of enhancing your fish’s “slime coat”, the barrier over its skin which serves as its best immune defense.

Test Kits test kit

Along with a pH kit, you will need ammonia, nitrite and nitrate test kits during the crucial “cycling” phase of your aquarium (more later). Freshwater "master" kits usually include all of these tests.




SETTING UP


Before you bring any fish home, set up your tank and equipment. This way you can make sure everything is running properly, and you can make repairs or exchanges before there are fish to worry about. More importantly, this step allows you to establish healthy water conditions before you bring fish home.

Leak Test

When you get your tank, fill the whole thing up with tap water. (Do not use bleach or chemical cleaners.) If your tank is large, you can do it in the yard with a garden hose. Set it on a level, solid surface first and cushion the bottom. If you have leaks, fix them with an aquarium-safe sealant, let it set and test again.

Aquascape

Once your tank is leak-proof, empty it and then place it in its final resting place. At this point you can begin “aquascaping”, or decorating your tank! Attach your background first.

Second, rinse your substrates in tap water – using a large bucket will make it easy (a 5 gallon bucket will be useful to you once you start doing water changes). Planting substrates may not need rinsing; check the packaging. Otherwise, rinse, drain and repeat until there is minimal clouding. Then you can add it to your tank.

Next, rinse your decorations in warm tap water and place them where you want them. You’ll be able to move them around later on, but you want them in the tank now to start building up bacteria.

Install and Test Equipment

Now install your equipment. Place your heater near your filter’s output for more even heating. Check your filter components and other equipment to make sure the parts are firmly connected and nothing is visibly broken. Make sure there is adequate space between the components and the wall behind your tank, and that you can access everything for maintenance.

Make sure any extension cords are properly grounded. Create “drip loops” in your power cords by weighing them down in one spot – this way any water that might drip down the cord will fall to the floor instead of going into the outlet and causing an electrical short.

Prepare your water with a water conditioner – even though there are no fish at this point, chlorine in tap water will kill the bacteria you need to colonize your substrates and filter. Then fill your aquarium – slowly! If adding plants, it’s easiest to plant them when your tank is about 1/3 or a ¼ full (depending on how deep it is).

Now, turn on your equipment and let it run. Make sure your lights work, and check for leaks or bad connections. Let your filter and heater and any pumps run from this point on. After a day or so, check that the temperature on your thermometer matches the thermostat setting on your heater.

Lights can stay off until you bring fish home – unless you’ve got plants, in which case you can begin to practice your lighting cycle – keep them on 10-12 hours a day or so, then turn them off at night.

CYCLING YOUR AQUARIUM


“Cycling” is the process of letting your tank accumulate healthy bacterial growth in its filters and substrates. Fish poop and uneaten food create ammonia when they decompose, and ammonia is toxic. The only thing that removes it is bacteria, which convert it into nitrite, also harmful, and then nitrate, harmless in small amounts. Nitrates are removed through water changes (and to a lesser extent, by plants). This conversion process is the “nitrogen cycle”.
Nitrogen Cycle


For fish to live safely, the nitrogen cycle must be complete – otherwise there is free ammonia floating in your water and it will kill your fish. Despite the growing number of websites dedicated to cycling, beginners often haven’t heard of it, and retailers don’t tell them! Why? Because cycling a tank can take as much as 4-8 weeks. This would discourage impulse buyers, not to mention they couldn’t send you home with a fish on that day.

Take heart - there are ways to speed up the process. Regardless of how you go about it, you will need ammonia, nitrite and nitrate test kits to figure out when your nitrogen cycle is in place. There are three basic methods of establishing the cycle.

Fishless Cycling

This method takes time, but is simple. Your tank should be completely set up with only the lights off. Now, “feed” bacteria by adding drops of pure ammonia, available and inexpensive at your grocery store (there should be no perfumes or additives). Test your ammonia levels after about half an hour – you want to get them to about 5 ppm.

After about a week, test again. Ammonia should have dropped, while nitrite will now appear. Add more ammonia to get the level back up, then wait another week or so. You may see nitrite spike when ammonia begins to fall - this is a good sign. In a few weeks, your ammonia levels should be dropping more quickly, your nitrite levels should be falling, and you'll see the appearance of nitrate.

At this point you can do a 25% water change, using water conditioner to prep the water. Repeat the process, replenishing conditioned water when it evaporates. Along the way you may see white cloudy water – these are bacterial blooms and will go away within weeks. Eventually you will have 0 ammonia and 0 nitrite, with low nitrate levels. At this point your tank is cycled.

Without help, this could take 6-8 weeks. However, there are some ways to speed it up. The quickest way to add bacteria is usually to find some from an existing healthy tank, from a friend or local fish store – a sponge filter, sand or gravel, or even dirty decorations will bring bacteria into your tank (make sure you transport them in water). Raising the temperature to around 85 degrees should help bacteria grow faster too.

“Cycling aids” are products which may increase bacterial growth, but they should not be relied on as instant fixes. Don’t assume you’re cycled when you first see 0 ammonia and nitrite –in an empty tank, the cycle can’t begin until you first have ammonia, which you can only get by “feeding” an ammonia source. You’ll still need to make sure that ammonia rises, followed by a drop in ammonia and a rise in nitrite, and then wait until ammonia and nitrite get back to 0 and nitrates are under control via water changes.

Cycling with Plants

Plants consume ammonia, nitrite and nitrates too, which makes the cycling process go much faster. With some plants it may only take days. You should test to see when it is safe to add fish. Consider using an air pump to make up for the oxygen consumed by plants at night (you can put it on a timer and only run it at night if you wish) – the bacteria you are trying to establish also need oxygen to survive.

Cycling with Hardy Fish

This is the most common cycling method recommended by retailers. It involves adding a couple of hardier aquarium fish to your tank and letting their waste establish the cycle “naturally”. The truth is that all fish are harmed by ammonia. It’s still a poison, and will shorten their life span and cause them great stress even if they survive.

If you were advised to take this route and are already committed, the best thing to do is add some sand or gravel or filter media from an established tank, quick! Adding a plant or two could help as well, but if the plant dies off remove it immediately, before it can decay and add to the ammonia load.

We heartily recommend that you use one of other cycling methods instead. Fish are animals too, and can be wonderfully interactive, with vivid personalities. It’s our responsibility to keep them safe and healthy. All this requires from us is a little patience.
ADDING FISH
Adding Fish

Finally you can add your fish! And because you’ve cycled your tank, you can fully stock your tank at once. However it is good practice to test ammonia, nitrite and nitrate levels after adding new creatures to make sure that everything is still going well.

Clip or secure the plastic bag containing your fish (one at a time) to the side of your tank. Float it there for a little while, then – over a period of 20 minutes or so – scoop a little water out of the bag and replace it with a water from your tank. Keep going until all the water in the bag is from your tank, then add the fish. This lets your fish adjust to the new temperature and pH gradually, avoiding shock.

Your fish may take a day or two to resume normal behavior, but the steps you have taken will give it the best chance of survival. Change about 25% of your aquarium water every week or when nitrate levels reach about 20-30 ppm. Make sure to siphon or vacuum excess waste from your substrates when you do.

You’re off to a great start! You can settle into a regular maintenance routine that won’t require much time and will bring great results. Avoid overfeeding and do weekly partial water changes - this is the best way to avoid a wide variety of problems that are timely and expensive to fix afterwards.

Clean filter components and equipment every few months, but avoid removing or cleaning large amounts of biological media or substrate at once – remember, you need the bacteria living on them.

Testing crucial parameters like ammonia or pH whenever there’s a change in your tank – a new fish, or a death or illness – will help you keep tabs on what’s happening; keep notes to track any potential developing problems.
THINGS YOU’LL NEED DOWN THE ROAD
Down the Road

Of course, you can pick these up as early as you want, but you’ll almost certainly want them soon after setting up your freshwater tank. There may be other things you determine you want or need later; I’ve tried to keep here to the basics.

Maintenance Equipment Quarantine Tank Lighting Timers and Automatic Feeders