Setting up a Freshwater Aquarium


The secret to successfully keeping fish is learning a little about their needs. Unlike pets that live on land fish are totally dependant on their keeper for absolutely everything they need. Setting up and stocking the tank correctly will make your experience easy and enjoyable.

The Freshwater Aquarium

fitting new aquarium lights by h080, on Flickr
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There are a number of reasons that new aquarist decide to set up a freshwater rather than marine aquarium. Cost is usually right up there at the top of the list and this is a big factor. The setup cost of a freshwater tank is usually 1/3 to 1/2 that of a comparable marine tank and the cost of fish can be even less.

Availability is another factor since no matter where you live freshwater fish are usually available where ever pets are sold. Along with the number of stores that sell marine species being fewer in number the variety offered is usually more limited than freshwater species. Difficulty usually rounds out the top three reasons as they've probably heard from more than one person that freshwater is much easier a fact that even the most dedicated marine aquarist would have to admit is true.

Regardless of the reason the new aquarist is faced with the same decisions that an old pro faces, namely what kind of fish and equipment to get. These two choices are tied together like the "Which came first the chicken or the egg question?". The fish you want to keep will dictate certain equipment decisions while the equipment you decide on will setermine what kind of fish you can keep.

. My Betta . by nica*, on Flickr
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For instance if you just fell in love with the sometimes almost dog like interaction that a friend has with their Oscar which can grow to more than a foot you certainly can't decide on a 2 gallon desktop aquarium. On the flip side if you are fascinated by the beautiful colors and flowing fins of a betta aka "the Siamese Fighting Fish" choosing a 55-gallon would be more than a little overkill.

These types of circular decisions are naturally tough to make often involving trade offs, substitutions and closer brushes with reality than we normally want to make when we want something. The easiest way to start though is always the same though establish your budget first. While individual choices in fish and equipment can significantly affect cost figuring on $10.00 a gallon to get a standard rectangular tank bubbling away in your living room is a good place to start.

For instance figure that a $100 budget should be enough for a 10-gallon aquarium. This would include everything in a basic setup Tank top gravel and decorations, supplies and even fish. A lot of trade offs are usually made like foregoing a heater or getting a smaller than recommended filter.

This is usually a recipe for problems down the road. If anything put off decorations or even some fish instead and add them as your budget allows.


Marigold Swordtails by Eric F Savage, on Flickr
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oscar tank by ellenm1, on Flickr
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Bubble Eyed and Fantail Goldfish by DanCentury, on Flickr
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There are literally hundreds of individual species of freshwater fish regularly available in the hobby. The easiest way to narrow it down is to ask yourself the following questions:

  • Do you want fewer bigger fish or more smaller ones?
  • Do you like active fish or fish that tend to glide through the water?
  • Is color or behavior more important to you?
  • Do you want a peaceful community or one with a lot of interaction between the fish?
  • Are you interested in having baby fish just for the experience?
  • Is there a certain kind of fish that you just have to have?


When choosing a tank there are 2 major considerations that affect the fish, one is the volume or number of gallons it holds and the other is the amount of surface area it has per gallon.

A larger volume means that chemical and temperature changes will occur more slowly and that a given amount of waste in the tank will be diluted in more water lowering its concentration. Slower changes and less concentrated waste are always better for the fish.

A larger surface area arrived at by multiplying the width times the height on a rectangular tank means that Oxygen can be absorbed and CO2 can be released more quickly. For a given volume of water say, 20 gallons, a higher tank will be either less long or less wide or both which reduces the surface area.

Non-rectangular tanks like hexagons are designed with visual impact as the main consideration and are usually taller than the rectangular tanks of the same size so these normally have the smallest surface area. To sum it up you can keep fish just fine in a taller tank just fewer than you can is the same volume tank with a lower design.


Filters are used to manage the waste produced in the aquarium. They use two methods to do this mechanical filtration that traps the waste for removal and biological filtration that relies on large numbers of natural bacteria. These eat the toxic ammonia (NH3) and nitrites (NO2) associated with the waste. All filters provide at least some of both of these types of filtration. There are three filter designs that are commonly used the power filter, the Under Gravel or UG filter and the canister filter.

Power filters are the type most commonly used. These typically hang on the back of the tank and pump water through a filter pad relying mainly on mechanical filtration. They are the easiest filters to clean and usually the cheapest but the filter pads eventually clog and have to be periodically replaced.

February 15 - 21, 2011 by osseous, on Flickr
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Undergravel or "UG" filters are the next most common design. These work by pulling fresh oxygenated water that contains ammonia and nitrites through the gravel. This allows large enough numbers of the natural bacteria to grow on the gravel to consume the waste produced. This natural cycle from fish food to fish waste and eventually to nitrates (NO3), which are basically fertilizer, is called the nitrogen cycle. When enough of the bacteria grow to convert all of the ammonia and nitrites to nitrates the tank is said be "cycled". It normally takes 6-8 weeks to cycle a new aquarium naturally but there are products available to speed up the process

The third most common design is the canister filter. These contain a stronger pump than the power filters and have a sealed chamber that can be loaded with a number of different filter materials referred to as the "filter media". The large volume of the chamber allows for large numbers of the waste-eating bacteria to grow providing significant biological filtration. The powerful pump allows for very fine media to be used providing mechanical filtration that traps even the smallest particles in the water leaving it sparkling clean. The canister itself is normally placed below the aquarium and is connected by hoses.


The most common type of lighting used on the standard rectangular aquarium is the fluorescent strip light. These often come as a combo that includes the tank and a molded plastic top. They are most often used with a full spectrum aquarium bulb that is designed to enhance the color of the fish and to grow plants.

Though much less common than in the past there are also screw in type incandescent fixtures available. These give off a lot of heat with incandescent bulbs but full spectrum compact fluorescent bulbs are available that are cooler, enhance the colors in the aquarium and provide proper lighting to grow plants.

The newest type of fixture uses led lights that give off virtually no heat and use very little electricity. They can be full spectrum or special color mixes for special effects.


Tank and stand by michaelmcd, on Flickr
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A fully decorated and filled aquarium weighs in at about 10 lbs a gallon. This is 100 lbs for a small 10-gallon tank but quickly goes up with the size of the tank. The weight in an aquarium is also what they call a dynamic load meaning that the load shifts as the water moves adding more stress to whatever it is resting on.

Store bought stands are specifically engineered to handle this type of load. These are often made of composite wood products but all wood and metal varieties are available.

Stands normally come in two basic types either cabinet or open frame. A cabinet stand provides storage below the aquarium and helps to hide any associated hoses and equipment. The open frame design is most common with metal stands and can normally hold a second tank on a bottom shelf.

Both of these are available in basic functional designs and ornate furniture grade stands that enhance any room.


The gravel also called the substrate is the material used to cover the bottom of the aquarium. In a freshwater aquarium commercial aquarium gravel comes in just about any color you can imagine and is the most common, chemically safe and versatile choice. Undergravel filters are also designed to work best with the common sizes and textures of these gravels. Materials designed for the marine aquarium should also be avoided in the freshwater tank as almost all are designed with the different water chemistry found in these tanks in mind.

Planted and certain species tanks like aquariums set up specifically to house killifish or freshwater puffers sometimes use a soil based substrate to promote better plant growth breeding or specialized feeding behaviors. However realize that choosing these materials involves specialized maintenance and chemistry considerations especially if they are not designated for aquarium use.

Choosing a material that is not specifically designed for aquarium usage is possible but this choice brings with it a host of considerations that challenge even a seasoned aquarist. There is also a significant amount of work involved in cleaning and preparing even suitable materials that are not designed aquarium use.

Temperature tools

Most species of fish kept in the home aquarium come from tropical climates and do best in temperatures in the low to upper 70's. Just 5 or 6 degrees outside of this range, even for a short period of time, can result in lasting problems from stress and disease as well as outright fish loss. The temperature range is only one consideration though.

How quickly a temperature change occurs is another. The tremendously larger volume in even the smallest pond ensures that changes occur slowly and provides a range of temperatures allowing fish to move to warmer or cooler areas as needed. For these reasons every aquarium should have both a heater and thermometer to help maintain suitable temperatures.

The most common designs used are either a completely submersible heater or what is called an immersion heater designed to hang on the back of the tank with the control knob above the water. These are usually less costly but also much more prone to breakage. Quality is another consideration with lower cost and quality heaters being more prone to failure.

A thermometer is required when using any type of heater in the aquarium. The two most common types are floating glass tubes which can break in the tank and adhesive strips that are applied to the outside of the tank and change color with temperature changes. Many aquarists find the adhesive strips the most convenient and easy to read. Like the heaters there are a range of qualities available with the better ones tending to be more accurate.

Test kits

Caring for tropical fish is really all about maintaining the water that they swim and breath in. New aquarists often confuse water clarity with water quality. Nothing could be further from the truth though, crystal clear water that you wouldn't hesitate to drink if it were in a glass can be deadly to fish and water that you wouldn't step in if it were in a puddle can produce some of the healthiest and happiest fish you will ever see. The chemical makeup is what matters most to the fish.

There are probably more things dissolved in the water that comes out of your tap and ends up in your tank than you can count but luckily only a handful normally result in problems keeping fish. Since the appearance of the water can't be used to judge the level of these the only way to determine these is through testing. Well actually there is another indicator of poor water chemistry in the aquarium namely sick and dying fish but in the long run testing is more economical and humane.

Four chemical levels are probably responsible for almost all problems in keeping fish. These are pH, hardness, ammonia and nitrites. Test kits are available for each of these. Your water should be tested periodically and whenever your fish appear to be sluggish or just not acting like they normally do.

Testing can be done in store by bringing a sample but since it should be done as soon as you notice your fish looking or acting differently this is usually inconvenient. Home test kits allow you to detect and correct problems early which is a key factor in maintaining healthy fish. This cost of these kits is usually less than the cost of gas for special trips to the store for testing.

Cleaning Equipment

cleaning the aquarium by osseous, on Flickr
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The proper cleaning equipment will make keeping your tank looking its best and help with maintaining your water chemistry. These should be designed specifically for aquarium use and used only for the aquarium to guard against chemical contamination.

While there are a number of specialized tools that make just about any cleaning task a pleasure to do there are a few that are must haves for any aquarium owner. These are a bucket to drain and fill the tank, a gravel vacuum to remove food and waste that has fallen into the gravel and a non-abrasive scrub pad to clean the interior glass and ornaments.

There are a few upgrades that can almost make cleaning your tank something you look forward to. One is a magnetic cleaner that allows you to clean the interior glass from the outside and another is a gravel vacuum that attaches to the faucet. These virtually eliminate toting buckets of water and the associated risk of spillage and are invaluable time savers for tanks larger than 20-gallons. Regular maintenance including water changes is the best way to keep your fish healthy and the easier you make it on yourself the less likely you are to put it off.