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How to Set Up a Fish Tank: A Step by Step Guide

Is it your first time setting up a fish tank? Beginners find that setting up the tank is one of the most difficult things to do once you become a fish owner. It’s true – it can be hard to properly set up everything in your new aquarium without prior knowledge. Water, fIlter, aquarium gravel, decorations, plants, fish – which goes first? To help new fish owners, we’ve made a step-by-step guide on how to set up a fish tank.

Two fishes in a tank

Step One: Planing

As with all things, planning is key. Before you even start looking at fish tanks and their equipment, you need to decide what fish you want to keep – which species you will get. Beginners should do a lot of research when planning, just to be sure they get everything they need. The choice of fish will impact the tank size, type, and equipment you need to get. Freshwater, saltwater, breeding, community, or small-sized tank – it all depends on the fish you will keep.

Step Two: Preparing Your New Tank

Once you’ve got all the necessary equipment for your tank, you’re ready to set everything up. Before you add any water, you need to make sure the tank is clean (with a new tank, all you need is to wipe off any dust it might have), but do not use any soap, detergents, or any cleaning supplies that have harmful substances.

Cleaning a Used Tank

If you have a used tank, you will need to dedicate some attention to its setup. You will need to remove any debris that might be in the tank and clean it with vinegar and kitchen roll (both the outside and the inside). If you have an acrylic tank, you should be careful as this material can get scratches easily. And be sure to check if your new (old) tank is leakproof by filling it with water (just a couple of inches) and leave it for an hour.

Placing the Tank in Your Home

Positioning the tank in your home is also an important part of setting up your pet’s new home. When placing it in the home, you should look for a place that has a power supply close but is not exposed to direct sunlight. The stand you get for the tank should also be strong to endure the weight.

Once you put the tank in the desired position, you will need to check its level with a spirit level or your eyes by filling it with an inch or two of aquarium water.

Step Three: Adding the Substrate and Water

The next step is to add substrate and aquarium water. The type of substrate or gravel you get depends on your preferences, but it is also slightly dictated by the type of fish you want to have. Some fish can only have certain substrates (for example, catfish usually need sandy substrate).

The amount of substrate you should get will depend on how thick you want it to be. It’s best to follow the rule of thumb or 1lb of substrate per one gallon of aquarium water. For thicker, you can add 2lbs per one gallon to create a 2” bed of substrate.

You can use the following measures as a guideline:

  • A 10-gallon aquarium needs 10-20 lbs of substrate
  • A 20-gallon aquarium needs 20-40 lbs of substrate
  • A 40-gallon aquarium needs 40-80 lbs of substrate
  • A 50-gallon aquarium needs 50-100 lbs of substrate
  • A 75-gallon aquarium needs 75-150 lbs of substrate
  • A 90-gallon aquarium needs 90-180 lbs of substrate
  • A 125-gallon aquarium needs 125-250 lbs of substrate
  • A 150-gallon aquarium needs 150-300 lbs of substrate

Washing the Substrate

Substrate comes prewashed when bought, but chances are that it will be dusty. Just to make sure that the tank doesn’t get cloudy, the substrate should be rinsed once before placed in the tank.

You can rinse the substrate by placing small amounts of the gravel in a bucket filled with cold water. Swirl the substrate around with your hand. If there is a lot of gravel to clean, you can clean it with a high-pressure hose. Some substrates can’t be washed this way, so just try to remove as much dust from the gravel as you can with less vigorous hand movements.

Once the substrate has been cleaned, you can add it to a thin layer without scratching the bottom of the tank. After you’ve filled the bottom, you can add the rest. After adding the substrate, you can add the water to the tank.

Adding Water to the Tank

If you have a small tank that can take 20 gallons or less, you should first install the equipment before adding water. For bigger tanks, you’ll need to add the water before the equipment. However, how you add the water depends on the type of tank – whether it is a saltwater or freshwater aquarium. Just don’t add tap water.

To prepare your saltwater tank, you need to use water (preferably not tap water) that has gone through reverse osmosis and a dechlorinator too. You will need to use a salt mix by following the instructions on the packet to ensure you’ve added the right amount.

For freshwater, you will need to use a dechlorinator on the tank’s water (when it’s filled). Make sure you follow all the instructions on the bottle, as well as its ml’s per gallon ratio (which is usually 1 ml of de-chlorinator per 20 gallons of water).

Just make sure you prevent the aquarium gravel or sand from being disturbed and moved as the water is poured in by using a saucer or a bowl and slowly pour the water.

Guppy fish

Step Four: Installing the Equipment

Once the fish tank is filled with water and substrate, you can install the equipment (except for tanks of 20 gallons or less). Every tank needs equipment, especially a filtration system. The filter is the most necessary part of your fish tank equipment. Installing the filter depends on the brand and type of filter you’ve chosen.

Internal filters should be placed on the tank’s back wall, with the wire reaching the power supply. External filters are usually placed within the tank’s stand, underneath it. Underwater gravel filters need to be installed before the water is added to the tank.

After taking care of the filter, you should also put in an aquarium heater (for saltwater and tropical tanks). Our advice is to put the heater on the tank’s side and put the thermometer on the opposite side to make sure the fish tank is heated consistently. You should also have a thermostat in the room where the tank is to ensure it doesn’t affect the water temperature(especially if you need room temperature water for the fish).

Adding air tubing and pump, water conditioner, and filter media is also recommended, but not necessary. Airline tubing and air pump will help the airflow through the tank and help the algae growth. Filter media (placed anywhere in the filter) will also contribute to the health of your tank by keeping the nitrogen cycle going and changing the water quality that is flowing through it. If you want to use tap water, make sure you get a water conditioner that will neutralize any heavy metals, chlorine, and chloramine that are toxic to fish.

Step Five: Adding Decorations

It’s time to decorate your tank! After setting up the water and equipment, you can add plants and decorations you want to have in the tank. Whatever you choose to decorate your tank with, you need to follow the plan you made at the beginning.

Before adding each item to the tank, you will need to rinse it to remove any dust. As for the position of each item in the tank – it’s up to you to choose. Just make sure you properly place plants in the foreground and background, as some plants are better suited for one option rather than the other. Do some research on the plant placement to ensure you have a visually appealing tank.

Step Six: Cycling the Tank

As part of your aquarium maintenance, you should cycle your tank. What does that mean?

It means you’ll have to wait a bit until you put your fish in the tank. Cycling the tank means building up the good bacteria that will contribute to the health of your fish. To do so, you will need to establish a nitrogen cycle that will transform any unhealthy elements that can show up in the water into beneficial bacteria that will take care of any form of ammonia-rich waste. The cycling process must be done carefully and before putting any fish in the aquarium.

In order to cycle the tank, you will need to let the tank run for a day with just the aquarium water (remember to not use tap water and to properly go through the previous steps). With the help of a cycling aid, you can seed the tank with good bacteria and slowly start adding fish to the water (never more than three fish a week). Using a water conditioner can also help you establish beneficial bacteria and help cycle the tank. You’ll also need to constantly do proper aquarium maintenance to ensure everything is okay with the tank and water.


Step Seven: Adding Fish

Now, it’s time to add your fish to the tank! As we mentioned previously, you’ll need to slowly add fish to the tank once you cycle it. The rule is that you can add three new fish to the tank each week (without overcrowding it).

After you’ve added your fish to the tank, you’ll need to acclimate your fish. Fish are sensitive to any changes in the water, so changing environments (like when you take fish from the water they’ve been to their new tank) can be stressful to them. Because of that, the process of acclimating is very important when you add fish to a tank. You should also consider quarantining your fish in separate places, as a part of proper fish care that will keep all fish healthy. If one of them has a disease, it is likely that they all will get sick, so quarantine is one of the most recommended actions for fish care, along with regular water changes and water testing for ammonia and nitrite levels.

To properly acclimate your fish, you should do the following:

  • Turn off the lights in the tank
  • Dim the lights in the room where the tank is placed
  • Float the bag with your fish for 15 minutes so that they can adjust to the temperature
  • Add half a cup of water from the tank to the bag every 4-5 minutes until the bag gets full
  • Discard half of the water from the bag and repeat the previous process
  • Slowly pick up the fish from the bag with a net and place it in the tank
  • Carefully observe your new fish for the next 24 hours to see if they have settled in properly
  • Write down any concerns or changes you might notice on your fish
  • Do weekly water changes and testing for ammonia and nitrite levels


  1. How to Set Up a Fish Tank and Keep It Clean – PetMD
  2. Fish Tank Setup (Beginners Guide): How to Set Up an Aquarium – Fishsubsidy


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