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Stocking A Nano Aquarium PDF Print E-mail
Written by Liz Marchio   

The term “Nano” Aquarium is often used by hobbyists as a descriptor for small aquariums, usually under 20-gallons in total volume. Many “nanos” are 10-gallons or less. These tanks with their small footprints are ideal for kids and/or desktops. However, due to their size, stocking them successfully with fish and invertebrates can become problematic. Some simply find it too hard to resist adding “just one more”! So, let’s talk about how to stock such aquariums with long-term success.


Longevity and Size

Many people think of fish as short lived animals.  This is true for some species such as annual killifish (for example, Nothobranchius species), which live, breed, and die within a year in the wild. Fortunately, most fish will live several years and make great pets if properly cared for. Many fish will live considerably longer.

Larger fish such as Goldfish, some Cichlids and Catfish can live more than ten years. Koi, which are ornamental carp, can live seventy years or more. It is not just the tank busters that are long lived, however. There are accounts of Corydoras aeneus catfish, measuring a diminutive 3”, living twenty years [site]. The point is: Take longevity into account. Part of the draw to keeping fish is to maintain them for their entire life.

Killifish may not live long, but they are productive during their time and are beautiful as well. These jewels may be ideal for children since their interests tend to wax and wane over time. It is important not to rope yourself into a larger growing, more long term pet if you cannot support it and its growth.

Goldfish are typically the  quintessential child’s first fish. However, this endeavor often ends in disaster for both the fish and the aquarist since these carp can grow large very quickly and consequently require copious amounts of work to properly maintain. In order to ensure your fish keeping experience is a positive one, steer clear of large species such as this.

“Fish Grow to the Size of Their Aquarium”

How many times have you heard this saying? The statement “it will only grow to the size of its aquarium” is true only because the fish become stunted due to confinement. The health of a fish confined in too small an aquarium will quickly decline leading to repetitive ailment and eventual death. Goldfish bear the brunt of this myth as they are often touted as the perfect bowl fish. A goldfish that could live ten years will only live one in such an environment. It is the responsibility of the aquarist to maintain appropriate volume of water for the fish species they intend to keep.

Simply put, know your limitations as an aquarist. If you cannot maintain a large species, don’t buy juveniles of that species. Likewise, if you plan on growing out a large species in a smaller aquarium, maintain proper water quality and make a concise plan to upgrade their aquarium in a timely manner. Remember too that fish keeping’s number one rule is to be an informed hobbyist. There are conscientious stores that will be honest about the care and adult size of certain fish, but there are also many stores that expect you to know what you are buying and thus will sell you anything you want. Buyer beware!

Stocking aquaria is usually the most confusing part of fish keeping. There is not a good way to simplify it. Most people will tell you that a freshwater aquarium can hold “one inch of fish per gallon of water”. This is not a bad way to think of stocking a tank, especially when dealing with small fish but there are a few things to keep in mind. When you add ten pounds of gravel to a ten-gallon aquarium, it displaces a fair amount of water. When you add rock or driftwood, it displaces more water. The ten gallons you once had is now probably 10% less and thus cannot hold as many fish as the rule states. Some fish simply produce more waste than others. 

Also it is important to take the mass of the fish into consideration.  For example the body mass of one ten inch Oscar is far more than that of ten one inch neon tetras and so, length itself cannot be the only qualifier for stocking levels. Lastly it needs to be said that you should include your algae eating organisms within your stocking total. They are in fact producing waste like the rest of the fish.

The Curse of the Kit

Be aware that many “complete” kits are complete for what the manufacturer thinks you want or what they think you need. For example, there are kits that do not include a heater. Small aquariums are not able to maintain their temperature with a light alone.

A reliable heater is one of the most important parts of a complete tropical aquarium. There are very few cool water nano-sized fish available to hobbyists. Keep in mind that there are many different types of aquarium heaters. The best types are those that have a built-in thermostat and are fully submersible. Many beginners buy the $12 hang-on the tank heater only to break it during their first water change. Instead of making that mistake, invest in a more expensive and reliable heater.

Most aquarium kits come with sufficient filtration. The fun part of fish keeping is realizing where you can simplify. If you make your own kit, you can use anything from a sponge filter to a wet-dry filter. The most popular choice is a hang on the back filter power filter, which unlike the hang-on heaters, are very reliable. One the most interesting way to filter an aquarium is by employing live plants to uptake the fish’s metabolites. You can strike a balance between the plants and fish where there is no need for outside filtration, however, water changes will still be necessary to maintain good water quality. This is a more advanced technique and will require some tinkering to get it right. Aquarium keeping is itself an experiment when you start out, so learn from your mistakes and take responsibility for your pets.

Shrimp as Pets?!

Who would have thought that shrimp, those delicious denizens of the sea, could be good freshwater aquarium pets? Shrimp, such as Neocaridina heteropoda, the Cherry Red Shrimp, stay small and can be housed in groups or in community tanks with small-mouthed fish. They are also, most importantly, easy to keep and great at eating algae. Although invertebrates such as shrimp can be difficult to understand, once you’ve tried them and got them to live they are quite easy to maintain and breed. By difficult to understand, I mean that many people treat all aquatic life the same. Invertebrates cannot be thought of as fish. They cannot withstand medications or large swings in pH or temperature as many well acclimated fishes can. Medications for “Ich” containing elements such as copper will quickly kill all invertebrate life.

There are a great many shrimp species now available to hobbyists. There are tropical and cool water species, so make sure the proper choice is made. Crystal Red Shrimp and Tiger Shrimp are both commonly kept cool water shrimp. Keeping them in warmer water can result in shortened lifespan.

Bacteria: The Most Valuable Life in Your Aquarium

The nitrifying bacteria coating the filter media as well as every other surface of your aquarium for that mater are the most critical life form you maintain within your tank. They are the foundation of any healthy aquarium. Their microscopic stature often causes them to be overlooked. These colonies create the perfect ecosystem to house fish and invertebrates. They do this by breaking down the toxic wastes produces by the fish and invertebrates into nitrate which is removed by plants, algae, and water changes.

It is very important that anything you do in, around or to your aquarium does no harm to your nitrifying bacteria. For example, if there is a disease issue in your aquarium, you need to be careful of what medications you use as many of them will kill off your nitrifying bacteria colonies. Doing so will cause severe damage to the balance of the aquarium. Shaking the balance of your aquarium at its foundation will be difficult to rebound from without casualties. Take care of your bacterial base and build your dream nano aquarium from there. Good luck!

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