Setting up a new freshwater fish tank can be daunting. It takes several steps, though it’s not as difficult as many think.
Before setting up a tank, the most important thing to consider is what kind of fish you want. By researching the species, aquarists can determine what tank and equipment they need.
Once they know what fish they want, aquarists can pick the right size tank and decide where to put it in their home. After the tank is in place, they can set up their equipment, including a filter, heater, and airstone.
It’s now time for aquarists to begin decorating their tank. Start with the substrate since it is heavy and hard to place after the tank is full of water. Once the substrate is in, aquarists can fill their tank with water and decorations.
Now that everything is set up, the tank can begin cycling. The nitrogen cycle makes the water safe for fish and is necessary before adding fish to the aquarium.
After cycling, test the water and make any necessary adjustments. Make sure that the pH, temperature, and water hardness levels are correct for the species.
Lastly, the aquarist can add the fish. Do this gently by acclimating them with the “drip” or “bag” method.
Remember that maintenance continues even after the tank is set up. Fish need regular care and cleaning to continue living happy and healthy lives.
New aquarists are likely to encounter problems, though they’re usually easy to fix.
- Choose Your Fish
- Get the Right Tank
- Gather Equipment
- Select Substrate
- Fill Tank
- Cycle Tank
- Test & Adjust Water
- Add Fish
- Clean & Maintain
Step 1: Consider The Kind Of Fish You’re Getting
Before setting up any fish tank, consider what kind of fish are going to be living there.
For example, bettas only need five gallons of water, while most cichlids need 30 gallons or more.
Tropical fish need a heater that creates warm water. Goldfish thrive without a heater.
It’s not enough to know how to set up any old tank. Prospective aquarists must research the specific needs of the fish they want to care for.
Step 2: Pick The Right Tank
Once an aquarist decides what kind of fish they want, they must pick the tank.
Aquarists should consider how many gallons they need.
Research online or talk to the local fish store expert to determine how much space the fish need.
Those planning to keep a community tank need more space than if they were to keep one species alone.
Consider whether a tall or long tank is better. Some tanks — like 29 gallons — come in tall and long options suitable for different species.
Fish like zebra danios prefer longer tanks. They are speedy travelers who like to move horizontally.
Angelfish and discus prefer taller tanks. They better accommodate their unique body shapes.
Picking The Right Stand
Choosing the right stand is as important as choosing the right aquarium.
Water is heavy — about 8 lbs (3.6 kg) per gallon. Factor in the gravel, equipment, and decorations, and the tank becomes very heavy.
Even a tiny 10-gallon aquarium weighs slightly over 80 lbs (36.3 kg). A 100-gallon tank weighs a staggering 800+ lbs (362.9 kg).
Pet stores sell stands explicitly made for aquariums. The safest thing for an aquarist to do is to buy the stand rated for the size aquarium they want to set up.
Many hobbyists buy a desk, table, or other heavy furniture to hold their aquarium. These are often cheaper and nicer-looking than traditional aquarium stands.
Heavy-duty furniture is an excellent way to go as long as the aquarist is sure it can hold the aquarium’s weight. Never try to place the aquarium on a piece of furniture that seems iffy.
NEVER place an aquarium on a piece of furniture shorter than the aquarium’s length. The aquarium’s edges should NEVER hang off the sides of the furniture or stand.
The aquarium may seem strong enough initially. Excess pressure is pushing on the edges of the glass or acrylic that isn’t being supported.
Over time, the glass or acrylic becomes weak enough to shatter.
Likewise, make sure the aquarium stand is level.
Fill the aquarium with about 1-2 in (2.5-5.1 cm) of water and check that the water is even on all sides of the tank.
An uneven aquarium stand can be dangerous because it can leak, crack, or even fall over.
Where To Place The Tank In Your Home
Hobbyists must decide where they want to place their aquarium before filling it.
Here are some places an aquarium should never be:
- Near a window — sunlight causes dangerous fluctuations and excess algae growth.
- Near heat vents or air conditioners — these cause dangerous temperature fluctuations.
- Close to outside doors — the outside air can cause dangerous temperature fluctuations.
Remember how much water weighs, and consider the total weight of the new aquarium.
It’s not enough for the stand to be strong enough to hold that weight — the floor must be, too.
Ensure the floor can bear the aquarium’s weight before setting it up. Setting up a heavy aquarium on a weak floor can quickly lead to disaster.
Many rental agreements state a limit for what size aquarium tenants can have in the rental unit.
Choose an area near an electrical outlet since most aquariums need two to three spots for plugs.
Set up the stand and aquarium far enough away from the wall that the filter and chords can run behind the aquarium.
Ensuring enough space behind the aquarium allows easy cleaning and general maintenance.
Step 3: Pick Out Your Equipment
Every aquarium needs some basic equipment — a filter, at the very least.
A heater and airstone are also necessary for most tanks.
Fish SHOULD NOT live in a tank or bowl without these essential pieces of equipment. Even betta fish need a filter and heater to live happily.
Filters
Every aquarium needs a filter — filters help to aerate the water and remove waste.
The type of filter an aquarist wants depends on the size of the aquarium and the type of fish.
Sponge filters are better for betta fish and small critters. They might experience injury or death from a HOB (hang-over-back) filter. They’re easy to clean and maintain, though they occupy physical space in the aquarium.
A HOB filter is suitable for most tank sizes between 5 and 100 gallons.
They are usually too big for aquariums under 5 gallons; we recommend a sponge filter instead.
Over 100 gallons, HOB filters aren’t usually enough. A canister filter is usually a better option.
Canister filters are excellent for larger aquariums. They operate outside the aquarium and are easily hidden inside the aquarium stand. They are large enough to hold biological and chemical filters.
Ensure that the filter is of good quality and is large enough to handle the amount of waste the fish produce.
Go up a size when housing especially dirty fish like plecos or goldfish.
Wait to plug the filter in until the aquarium is full. The water should rise past the filter’s minimum fill line, which should be indicated on the filter.
Turning the filter on before there is enough water in the tank can cause the filter to burn out.
Heaters
Most freshwater fish sold in pet stores come from tropical regions and need a heater in their tank.
Without a heater, tropical fish develop lowered immune systems. Poor immune systems leave them susceptible to illness and death.
Heaters also keep the temperature stable year-round, regardless of the season.
NEVER turn a heater on in dry air. It can cause the heater to burn out and break. Glass heaters may even crack.
Fully submersible heaters should be completely submerged before turning them on. Place them near the filter’s intake for proper distribution of warm water.
Non-submersible heaters may have a minimum fill line. That line needs to be reached before turning the heater on. These heaters should sit next to the filter’s outflow for proper distribution of warm water.
Wait to turn the heater on until it’s been in the water for about 20 minutes. The time allows the internal thermostat to read the temperature of the water. Without waiting 20 minutes, the heater might overheat.
Some fish, like goldfish and white cloud mountain minnows, don’t need a heater. They are cold-water fish that are happy at room temperature or slightly below. They even do well in temperatures below that, though most don’t keep their homes that cold.
While most hobbyists need a heater for their tropical fish, it’s unnecessary for everyone.
Those in tropical regions with a stable temperature are often okay without a heater. The region’s temperature usually stays in the high 70s, which is great for most tropical fish.
Place a thermometer on the opposite side of the aquarium as the heater. Make sure the thermometer is in a location that is easy to check.
Air Stones
Some fish need a lot of oxygen and need an airstone.
Air stones hook up to tubing and an air pump that blows air through the air stone to create bubbles. The bubbles rise to the surface, popping and creating oxygen exchange.
Air pumps are often good for aquariums with weak filters or tropical temperatures.
While many fish like still water, the lack of currents creates a lack of oxygen. Likewise, warm water holds less oxygen than cool water.
Do All Fish Need Airstones?
A few fish don’t need airstones, like bettas and gouramis. They live in areas that are naturally low on oxygen, meaning they are used to it. They’ve developed labyrinth organs. The organs allow them to breathe air from the surface when there is insufficient oxygen in the water.
It’s better to use an airstone in every tank, all things considered. They are unlikely to hurt fish.
Ensure fish that like calm waters have space to rest. The current from the air stone shouldn’t affect the entire tank.
Only turn the air pump on once the airstone is wholly submerged.
Step 4: Pick Out The Substrate
The type of substrate an aquarist should buy depends on their fish’s needs or preferences.
Cichlids typically need higher pH and water hardness levels. Aragonite sand and crushed coral are great for naturally raising pH and hardness.
Bottom-dwellers, like Corydoras catfish and loaches, prefer sand or fine gravel. These substrates are easy to sift through and are soft on their sensitive bellies.
Those who aren’t planning on having sensitive bottom-dwellers have more options. River rocks or irregularly shaped gravel add variety and color to the tank.
Pick enough substrate to form a layer about 1-2 in (2.5-5.1 cm).
After picking out the substrate, place it in a large, clean bucket and rinse it out to get rid of dust and debris. Rinsing substrate before putting it in the tank is safer for the fish. It also keeps the aquarium looking nicer.
Fill the aquarium with the substrate after rinsing. Be careful not to scratch the sides of the tank.
Step 5: Fill The Tank With Water
Place a plate upside down on top of the substrate and pour the water onto the plate.
Adding water like this prevents it from disturbing the substrate. Placing the plate upside-down prevents the water from splashing up and out of the tank.
Only fill the aquarium one-third full at first. Stop and check the aquarium for leaks. Dry the sides and bottom of the tank if there was any splashing during filling.
Leaks often cause water to pill up at the edges of the aquarium. Water might also begin to run down the sides of the aquarium stand.
While fixing leaky tanks is possible, it’s tricky; beginners should not attempt it. Instead, simply return the tank to the store and replace it with a new one.
Continue filling up the tank if there is no leaking.
Add a dechlorinator to the aquarium to get rid of all chlorine and heavy metals. There won’t be any fish living in the aquarium for at least two weeks; the dechlorinator helps get the tank ready.
Adding The Decorations
We recommend adding decorations after the tank is about half full.
Remove the plate from the substrate. The water level is high enough that adding water should not disturb the substrate.
Add the decorations, ensuring they are firmly planted in the substrate.
Hobbyists can add decorations after the tank is full, though it’s not as easy.
Decorations take up space. Adding the decorations last may cause the tank to overflow if the aquarist is not careful. It also requires the aquarist to get more of their arm wet, which some find unpleasant.
Add an aquarium background before filling the tank with water if using one. It’s much easier to attach the background to an aquarium that is not heavy with water.
Which Decorations Are Best?
Choose decorations that the fish are likely to enjoy most.
Bottom dwellers like lots of caves and rocks to hide in.
Tetras and barbs love many plants to explore (live plants are always better than fake).
Cichlids typically prefer more open space and aren’t happy with tons of plants and decor.
Research the fish species before choosing decorations.
Turning On The Equipment
Now that the tank is full, it’s safe to plug in and turn on all equipment.
Keep enough space between the equipment and the electrical outlet to create a “drip loop.” A drip loop is a loop in the power chord that sits slightly below the electrical outlet.
The purpose of a drip loop is to prevent fires and electrical shock. Any water that drips down the power chord gets stuck at the bottom of the loop. It won’t run into the electrical outlet, which is dangerous.
Step 6: Cycle The Tank
Aquariums must go through the nitrogen cycle before they are safe for fish.
The nitrogen cycle occurs when beneficial bacteria begin growing in the tank. The bacteria break down waste and make the water safe for fish.
Fish-In Cycles
Some experienced aquarists do “fish-in” cycles. They add hardy fish — like zebra danios — to the aquarium immediately. Zebra danios are exceptionally hardy and are likely to survive the process.
Fish-in cycles make the nitrogen cycle go faster. It goes faster because the fish are actively producing waste.
Although fish-in cycles are quick, we don’t recommend them. While hardy fish are likely to survive the process, it’s still very stressful and harmful to their health.
Use Nitrifying Bacteria To Start The Nitrogen Cycle
We recommend adding nitrifying bacteria to the water. It helps to jump-start the nitrogen cycle so that the aquarium cycles faster.
It’s not required, as we can start the nitrogen cycle other ways, though it helps speed things along.
Use Fish Food To Start The Nitrogen Cycle
Another way to start the nitrogen cycle is by adding a small amount of fish food. As the food breaks down, it turns into ammonia.
What Happens During The Nitrogen Cycle
Bacteria slowly begin growing in the aquarium. It breaks down any ammonia in the tank into nitrites. The bacteria then break the nitrites down into nitrates.
Here is a breakdown of what happens during the nitrogen cycle:
- First, the ammonia should spike, while the nitrites and nitrates are 0 ppm.
- Second, the nitrites begin to spike, while the ammonia drops and the nitrates remain at 0 ppm.
- Third, the nitrates spike, while the ammonia and nitrites are back down to 0 ppm.
- Lastly, the nitrates should drop. Nitrates are less toxic than ammonia and nitrites — it doesn’t have to drop all the way to 0 ppm.
Step 7: Testing & Adjusting The Water Parameters
Test the water every day until the nitrogen cycle is complete. Testing every day makes it easy to see that the nitrogen cycle is progressing as it should be.
Write down the ammonia, nitrites, and nitrate levels, and watch as they change daily.
Once the nitrogen cycle is complete, then it’s safe to add fish.
The water parameters should look like this before adding fish:
- Ammonia: 0 ppm
- Nitrites: 0 ppm
- Nitrates: <40 ppm (Some sensitive fish need less than this)
Testing Doesn’t End After Adding Fish
Continue testing the water regularly — at least once a month — to make sure it stays safe for the fish.
Use the water test results to adjust the aquarium water and make it safe for fish.
A water change may be necessary if there are ammonia, nitrite, or nitrate spikes. The spikes may also be due to overfeeding or other issues.
Use the water tests to keep the pH within safe levels. There are ways to lower and raise pH, both naturally and chemically, if needed.
Likewise, use water tests to determine the hardness and whether it needs adjusting.
We recommend using API’s Freshwater Master Test Kit. It is one of the most affordable and accurate kits on the market.
Steer clear of test strips, as they are not very accurate.
Step 8: Add The Fish
Don’t add too many fish simultaneously, which can cause a dangerous ammonia spike.
We don’t recommend adding more than five or six fish at a time.
DO NOT simply toss the fish into the aquarium. The difference in water parameters can cause them to go into shock and die. Always acclimate new fish to an aquarium.
We prefer acclimating fish using the drip method as it is the most gentle method. The floating bag method is another good way to transition fish to their new water easily.
In short, acclimating fish involves gradually adding some of the new water to their old water. Doing this slowly gets them used to their new environment.
The slow transition prevents them from going into shock once they enter their new tank.
Step 9 & Beyond: Cleaning & Maintenance
Fish are living animals, and as such, the aquarium needs regular cleaning to get rid of waste.
Clean the tank once every week or two weeks.
Scrub the decorations and the sides of the tank to remove waste and algae.
Use a gravel vacuum to clean the gravel, and remove 15-30% of the water.
Clean the filter and change disposable filter media about once a week.
Never use soap or harsh chemicals around or in the aquarium.
Freshwater mixed with a bit of vinegar is usually enough. Use the mixture to clean off decorations and the outside of the tank.
Common Problems With New Fish Tanks
Some of the most common issues new aquarists face are ammonia spikes and pH fluctuations.
Cloudy water is common with brand-new tanks. Green water occurs with too many nutrients.
Cloudy Water
Cloudy water in a new fish tank is very common; it’s a bloom of new bacteria growing in the tank. The cloudiness should clear up as the nitrogen cycle reaches its end.
Cloudy water that continues to occur may be due to excess minerals or dust from the substrate.
Try switching to RO (reverse osmosis) water to get rid of minerals.
Use a gravel vacuum to suck out any excess dust from the gravel.
Fluctuating pH
An unstable pH may occur due to too much CO2 in the tank because of too much waste. It can occur due to overfeeding or if the water is too stagnant.
Do a water change to get rid of waste, and consider adding an airstone for better circulation.
Spiking Ammonia
The tank may not be done cycling, or there is too much organic material.
An overstocked tank can cause an ammonia spike, as can overfeeding.
Green Water
An algae bloom causes green water due to too many nutrients.
An aquarist might be overfeeding their tank, there may be too many fish, or the tank may be receiving too much light.
