How to Set up a Fish Tank: A Beginner's Guide

Updated on October 1, 2016
A healthy tank with Neon Tetras.  Note the oxygen being produced by the healthy plants in the tank.
A healthy tank with Neon Tetras. Note the oxygen being produced by the healthy plants in the tank. | Source

Why Did My Fish Die?

Years ago when I worked in the aquatic section of a pet shop, I would often have customers come into the store and tell me that they had purchased an aquarium (usually from somewhere else) and set up their tank only to have their fish die soon after.

Setting up and maintaining an aquarium is actually quite easy if you understand the needs of the fish and how to keep them healthy.

The Nitrogen Cycle

One of the most important things to understand about an aquarium is the nitrogen cycle.

In order for your fish to stay healthy your aquarium must have a good nitrogen cycle. This process may take several weeks or months to complete.

Stage 1: Ammonia

Ammonia can be very harmful or deadly to tropical fish.

As soon as you add fish or plants to your aquarium, ammonia is starting to be produced in your aquarium.

Decaying plants, uneaten fish food and fish waste all contribute to the production of ammonia in the tank.

Stage 2: Nitrites

If given the opportunity, a bacteria called nitrosomonas will start to develop in the aquarium. These bacteria help to convert harmful ammonia into nitrites.

Unfortunately Nitrites are also toxic to aquarium fish.

Stage 3: Nitrates

Soon another type of bacteria will start to do its work of converting nitrites into nitrates.

Nitrates are not as harmful to fish as nitrites or ammonia as long as concentrations of nitrates don't get too high.

Live plants can help reduce the nitrates in the tank but the easiest way to control nitrates in an aquarium is to do partial water changes.

Using an aquarium test kit will help you to monitor the water quality in the aquarium and help to determine when water changes need to be done.

A good rule of thumb is to change 1/4 to 1/3 of the water once a month.

Easy to use aquarium vacuums are ideal to help do the partial water change as well as clean up excess debris from the bottom of the tank.

Using a Gravel Vacuum & Helpful Tips

Common "Beginners" Mistake

One of the most common mistakes I've seen time and time again for beginners is performing complete water changes.

Completely removing all the water from the tank destroys the nitrogen cycle and causes the process to have to start all over.

The need to do full water changes is usually caused by trying to put too many fish in an aquarium before it has a chance to develop the nitrogen cycle.

Advantages of Modern Aquariums

Fortunately modern filtration systems in today's aquariums help to make the process of keeping a healthy aquarium much easier.

Most modern filtration systems have three parts to them that help to ensure a healthy environment for your fish.

Overloading the Nitrogen Cycle

Adding too many fish to your aquarium at one time overloads the nitrogen cycle causing an overabundance of bacteria and depleting the tank of oxygen for the fish.

Another common mistake that overloads the nitrogen cycle is overfeeding your fish. You should never feed your fish more than they can eat in a two minute period.

When bacteria levels get too high, the water becomes cloudy and the fish start to show signs of having difficulty breathing. If left untreated, the fish will soon die.

Mechanical Filtration

Mechanical filtration removes large pieces of material from the tank by physically trapping them with material that is designed to act as a sieve to strain out the larger particles from the water.

This mechanical filter often looks like a sponge or fibrous material.

Cleaning mechanical filters can be done by removing them and rinsing them off to be reused.

Chemical Filtration

Chemical filtration uses substances to help remove substances dissolved in the water that cannot be remove by mechanical filtration.

One of the most commonly used chemical filters is activated charcoal.

Biological filtration

Numerous products are available to help improve biological filtration. These products are highly porous giving a greater surface area for beneficial bacteria to grow.

This is where much of the ammonia and nitrites are removed using the nitrogen cycle.

Some Great Aquascaping Examples

Tank Setup Example

I recently set up a tank that I will be using to raise Class N Endler's Livebearers. These fish are very easy to care for but do like to have lots of plants for the fry (babies) to hide in.

Preparing the Tank

I was very fortunate to acquire a 12 Gallon AquaPod aquarium at our local thrift shop for only $10. These tanks are almost always used to set up a saltwater aquarium but will work very well for freshwater use.

Because the tank was used it was important to make sure that there were no diseases left over from the previous occupants.

To make sure the tank was properly cleaned, I filled the tank with water and a gallon and a half of hydrogen peroxide. Fortunately our local Walmart sells quart size bottles for only $0.88 a bottle.

Hydrogen peroxide will break down over a 24 hour period into water and hydrogen leaving no harmful chemicals in the tank and is highly effective in killing any diseases that may be left in the tank.

I ran the pump and let the hydrogen peroxide and water mixture sit in the tank for 24 hours.

After 24 hours, I emptied the tank.

Foam filter media I cut to size for use in my new aquarium setup.
Foam filter media I cut to size for use in my new aquarium setup. | Source

Adding the Filter Media

I then added the filter media. This particular type of tank actually has the filter system built into the tank it however because this was a used tank, it did not come with any filter media.

I then went to our local pet shop and gathered some of the things I needed for the tank.

The first thing I needed was a mechanical filter media. I found a sponge like filter media that was big enough to fill the opening in the tank and cut it to fit perfectly. I had to purchase and cut two of them to get the filter to effectively cover the opening of the next chamber.

At this point I stopped adding filter media because I did not need the chemical filter yet and I did not find an affordable option for a biological filter in the pet shop.

These small "Bio Balls" have foam squares inside.  Very reasonably priced out of China.
These small "Bio Balls" have foam squares inside. Very reasonably priced out of China. | Source

Finding the Biological Filter Media

Because I couldn't find affordable biological filter media at my local pet shop I went to eBay to see what I could find.

I was able to find some affordable 16mm Bio Balls that had sponge in the center that I liked and were at a very reasonable price.

Unfortunately the Bio Balls had to come from China so I had to wait a week before adding them to my tank.

While I was waiting for the bio Balls I also ordered some filter media bags to put the Bio Balls and chemical filter media into.

The bag I received was fairly small so I'll probably order a couple more in the future.

The Chemical Media

Once I had the filter media bags I purchased the chemical media and bio balls, I decided to use a carbon and zeolite blend for the chemical media.

I simply poured the blend into a filter media bag and then rinsed it thoroughly before placing it in the middle chamber of the aquarium.


The substrate is the material that you use for the bottom of the tank such as gravel or sand.

Because I wanted to use live plants in my aquarium I purchased Black Floramax Premium Aquarium Substrate.

I chose this brand because it was the only brand that was available in my area that looked like it would be beneficial to my plants.


The hardscape is the decorations you put in your tank such as rocks or driftwood. These pieces form the main focal points for your aquarium.

In my case I used a piece of black and white marble that I collected from southern Arizona. I cleaned the rock well before using it in the tank.

To make the rock look more natural I partially buried it in the substrate.

Aquarium Plants

The fish I plan to add to my tank really like to have live plants to hide and feed on. I selected a few plants that would be easy to keep in the tank and gave the aquarium the look I wanted.

Fortunately the tank I'm using has a great lighting system for the live plants.

One of the plants I selected was Dwarf Hairgrass, I purchased one package and then separated it into small clumps and spaced them somewhat evenly throughout the front of the tank.

If the Hairgrass does well, it should form a carpet of green in a few months.

Depending on how things go I may make a homemade CO2 system for the tank at a later date.

Preparing Hairgrass for Planting

Small Green Cory Cat added to aquarium two weeks before adding more fish.
Small Green Cory Cat added to aquarium two weeks before adding more fish. | Source

Adding Fish to the New Aquarium

After letting the plants adjust by themselves for a week I added one fish, a small green Cory Cat. This will help get the nitrogen cycle going while I wait to add more fish.

After a couple of weeks I ordered my Class N Orchid Endler's Livebearers and added them to the tank. Of course, I set the bags with the fish in them in the tank for 15 minutes to allow the water temperature to equalize as always.

At this point the tank should pretty much take care of itself other than some partial water changes, cleaning of glass and other surfaced and periodic changing or cleaning of the filter media.

Below is a picture of the tank just after adding the Orchid Endler's Livebearers.

The aquarium soon after adding the fish.
The aquarium soon after adding the fish. | Source
Aquarium with Orchid Endler's Livebearers added a little more than two weeks after adding the Green Cory Cat.
Aquarium with Orchid Endler's Livebearers added a little more than two weeks after adding the Green Cory Cat. | Source

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