Freshwater Aquarium Basics

Welcome to the aquarium hobby! Keeping a tropical freshwater aquarium is a great hobby for young and old, and can be a stepping stone for keeping more complex aquaria. The following is introductory course covering everything you will need to set up and maintain a tropical freshwater aquarium.


The first step before any well planned aquarium is research. Take the time to study about what kinds of fish you would like to keep. Once you have an idea of what you like to add to your aquarium, you can find the water parameters they require and match tank mates and equipment to what they will need to thrive.

Aquarium Size

Almost any size aquarium is suitable for freshwater fish. However, the smaller the aquarium, the smaller and fewer number of fish you can keep. Many beginners start with a 10 gallon aquarium, but as with saltwater aquariums, bigger is better. A larger freshwater ecosystem can better handle the daily fluctuations in water quality than a small ecosystem, absorbing more toxins and reducing stress on the fish. Before buying your aquarium, take into account the adult size of the fish you are going to purchase and this general rule: one inch of fish body (not including fins) per one gallon of water in the aquarium.

Setting Up Your Aquarium

The key to any aquarium is good filtration. You can choose from several types, including power filters, a canister filters, or a wet-dry systems (for larger or heavily stocked tanks). Make sure there will be adequate bio-filtration to break down uneaten fish food and waste. If you have any questions or need direction, check with one of our knowledgeable aquarium experts, as these types vary with the size of aquarium and fish desired.

You can use any type of Substrate or gravel that is meant for freshwater to cover the bottom of your aquarium. It is important to select a substrate or gravel meant for freshwater so it will not buffer or raise your pH. We offer several size gradients and colors from which you can choose to fit your personal preference. If you wish to keep live plants or a special type of fish (like stingrays) more specific substrates will be needed.

Adding plants and decorations allows you to add your personal style and touch to your aquarium's environment. They also give your fish spaces to swim through and hide if they need a break from the stress.

A heater is required to keep the temperature of your aquarium water between 76-80 degrees F. Proper water temperature will keep your fish's immune system working properly.

Lighting requirements can vary, depending on if you are keeping live plants. If you are only keeping fish, a simple fluorescent bulb or LED fixture will suffice. Lights should be left on for a maximum of 8-10 hours a day to prevent the growth of unwanted algae.

Keep test kits on hand to monitor your water and watch for changes in water chemistry that can harm your fish. Important parameters to test include pH, ammonia and nitrite. You can also monitor nitrate and phosphate levels to keep algae sources under control.

Cycling Your Aquarium & Adding Fish

Before adding your chosen fish, your tank must "cycle" or become biologically stable. Cycling is the process where a nitrifying bacteria colonizes in your filter and gravel. This bacteria's job is to detoxify the wastes created by your fish. You will notice that within the first few weeks by testing your water, ammonia and nitrite levels will rise in the tank and slowly decrease. Also during this time you may see the water in the aquarium start to cloud or look grey. Do not worry, this is natural, the cloudiness will pass quickly on its own, or you can add a bacterial supplement such as Stress Zyme or Stability to help lower ammonia levels and aid in the cycle.

Fish can be added about three days after setting up your aquarium. This time allows the temperature and pH to stabilize. The first fish you should add are starter fish. The cycling process is very stressful for most fish so we recommend hearty starters that can handle adverse conditions. These are usually danios, small, non-aggressive fish that come in several colors. These fish will eat and create waste, spurring the growth of the beneficial bacteria that will help complete the cycling of your aquarium.

While your aquarium is cycling do not change any water or clean out your filter media. The loss of bacteria will set your cycle period back, increasing the time you have to wait before adding other fish. Your tank will be completely cycled when ammonia and nitrite both test at zero and nitrate tests low. This can take anywhere from 3 to 8 weeks. The key here is to be patient.

Adding New Fish

When your aquarium is cycled, add new fish gradually. Adding too many fish at once can disrupt your cycle and increase the possibility of fish illness. Check our Acclimation Procedures Guide for the keys to success when adding new fish and ensure a healthy transition for your fish.

Aquarium Maintenance

Once cycled, basic aquarium maintenance includes feeding, cleaning, and water changes. When your purchase your new fish, find out what food is best and how often they should be fed. Freshwater foods are available in flake, pellet and frozen varieties and each type of fish has different preferences. Cleaning maintenance includes scraping algae from the glass and siphoning your gravel to remove uneaten food and waste. Water changes are important because they help remove waste and food that hurt water quality, and they help add trace elements, nutrients and electroytes that keep your fish happy and healthy.

With this basic information you are well on your way to keeping a tropical freshwater aquarium. If you have any questions or think you might like to graduate to more complex aquariums like saltwater and reef, feel free to contact us at 888-842-8738 or You can also find informative articles on That Fish Blog at or post your questions on our Facebook page. We at That Fish Place - That Pet Place want to keep you and your fish happy for years to come!

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