From Novice to Expert: The Ultimate Guide to Freshwater Fish Keeping

Becoming a freshwater fish keeper can be an enjoyable and rewarding experience. However, it's essential to understand the basics of fish keeping before starting. In this ultimate guide, we'll cover everything you need to know to become a successful freshwater fish keeper.

The Nitrogen Cycle

The nitrogen cycle is a biological process that occurs in aquariums, and it's mandatory for maintaining a healthy environment for fish and plants. In simple terms, the nitrogen cycle converts harmful ammonia in the water into less harmful nitrite and eventually nitrate. Nitrate is only toxic in really large quantities. An easy way to reduce it is to add real plants to your aquarium.

The process happens naturally in aquariums, but it can take anywhere from a week to several months, depending on the method you choose (there are products on the market that help with cycling your aquarium so you don't wait weeks or months).

The goal of the nitrogen cycle is to establish thriving colonies of 2 types of beneficial bacteria. These bacteria consume ammonia (Nitrosomonas,  Nitrosococcus bacteria) and nitrite (Nitrobacter), which can be harmful to all the creatures in the tank. One type of bacteria converts ammonia into nitrite, while the other type converts nitrite into nitrates.

Before we explain how the nitrogen cycle actually works, you must set up the aquarium. Add some décor (plants, substrate) if you wish, fill the tank with water, and add a filter to the aquarium with an aquarium safe sponge(HOB or hang on the back filters are very popular). The sponge acts as a filter that cleans up the tank, but also as a home for the beneficial bacteria.

The Process:

  1. 1
    Add water conditioner to the water to render it safe for the bacteria colonies and for future livestock (in many areas, water can contain various harmful elements which kill bacteria)
  2. 2
    Start building the Nitrosomonas,  Nitrosococcus colonies by adding some ammonia to the aquarium. This can be done by adding literal ammonia (some companies sell this for aquarium use, like Fritz Aquatics: Ammonium Chloride. Make sure to follow the instructions on the label!) or you can add a little bit of fish food every 2-3 days
  3. 3
    Once the ammonia bacteria start multiplying, nitrite will be created. Now we wait for the Nitrobacter colonies to eat the nitrite and create nitrate
  4. 4
    During this process, test the water parameters for ammonia, nitrite, and nitrate daily. Our goal is to get to a point where ammonia and nitrite disappear within 24 hours, leaving only nitrates
  5. 5
    If your water tests display 0ppm of ammonia and nitrites, then you are almost done! Check the nitrate levels. If they are over 20ppm, do a large water change (~50%) and wait a day before doing another test
  6. 6
    Once your water parameters are as follows: 0ppm ammonia, 0ppm nitrite, <20ppm nitrate, you ready for fish!!!
  1. Water Chemistry

Understanding water chemistry is crucial for maintaining a healthy aquarium. 4 key parameters to keep in mind are pH, hardness, alkalinity, and temperature.

pH is a measure of the water's acidity or alkalinity. A lot of freshwater fish prefer a pH between 6.5-7.5 (while saltwater is generally in the 8.0 - 8.4 pH range), but the ideal range can vary depending on the species. You can adjust the pH by adding chemicals or using special substrate designed to alter the pH. Be very careful when using chemicals. It can change it FAST which will shock and can certainly kill the livestock

Water hardness refers to the amount of dissolved minerals in the water. Most freshwater fish prefer water that is moderately hard, with a general range of 4-12 dGH (degrees of general hardness). You can adjust water hardness by adding minerals to the water or using special substrate designed to increase hardness.

Alkalinity is a measure of the water's ability to buffer changes in pH. Maintaining proper alkalinity is essential for maintaining a stable pH.

It's crucial to check for ammonia, nitrite, and nitrate levels regularly, and adjust pH, hardness, and alkalinity as needed.

Aquarium Location

The location of your aquarium can have a significant impact on its health and success. You want to avoid placing it in direct sunlight or near a heat source as this can cause temperature fluctuations. Direct sunlight can also promote the growth of algae, which can affect plants by growing on top of them, plus most algae looks awful.

You also need to ensure the aquarium is on a stable surface that can support its weight. A filled aquarium can be heavy, and it's essential to make sure it's supported correctly to avoid accidents.

Getting Ready to Set up the Aquarium

Before setting up your aquarium, there are several essential factors to consider. Water temperature is a crucial factor to consider, and it's vital to choose the right heater for your aquarium size. A large number of freshwater fish prefer a temperature range of 72-78°F, but some species may require different temperatures.

Lighting is also an essential consideration, and it can impact the health of fish and plants. If you plan to keep live plants, you'll need specific plant lighting. Lighting should be kept on for 6 - 10 hours a day to simulate natural light conditions.

When it comes to décor, you have the option of using real plants or artificial plants. Real plants can help to reduce nitrate levels in the aquarium, while artificial plants require less maintenance.

Although artificial plants may seem easier initially, there is a potential drawback to their use. Some artificial plants have sharp edges that can increase the likelihood of injury to fish. Live plants will not injure fish, while at the same time they create oxygen and eat nitrates.

Substrate is also an essential consideration when setting up your aquarium. The substrate is the material used to cover the bottom of the tank, and it can impact the health of fish and plants. Gravel is a popular substrate choice, but it's essential to choose a size that won't harm fish or prevent beneficial bacteria from growing.

Filtration is another crucial factor to consider, as it plays a significant role in maintaining water quality. A good filter will remove excess food, waste, and other debris from the tank, helping to prevent harmful buildup and maintain a healthy environment for fish.

Lastly, it's important to consider the size of your aquarium and the number of fish you plan to keep. Overcrowding can lead to poor water quality and stress among fish, so it's vital to choose a tank size that provides enough space for your fish to swim and grow comfortably.

By considering all of these essential factors, you can set up a healthy and thriving aquarium that provides a safe and enjoyable home for your fish.


In conclusion, becoming a successful freshwater fish keeper requires an understanding of the basics of fish keeping.

One essential process for maintaining a healthy environment for fish and plants is the nitrogen cycle, which converts harmful ammonia into less harmful nitrite and eventually nitrate. The process takes time but can be sped up with bacteria in bottles which can usually be found in aquarium stores.

It's essential to test water parameters daily so you can quickly notice any changes in the water parameters (sudden changes will stress out livestock, and can be fatal).

Additionally, aquarium location, water temperature, and lighting are crucial factors to consider before setting up an aquarium. Whether using real or artificial plants, it's crucial to ensure that the aquarium environment is safe and stable for the livestock.

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