Selecting the Tank.

As with any project, the key to success is planning. Before entering the hobby in a meaningful way, many people are exposed to a fish bowl or someone else's aquarium. While many of us are drawn to 500 gallon tanks with sometimes hundreds of fish or beautiful planted set ups, the reality of the situation is that these tanks are no small undertaking. If you decide to purchase a fish tank, you're also purchasing the responsibility that comes with it. Weekly syphoning of the gravel, cleaning dirty filters, water changes that are sometimes larger than you'd like, and of course all the problems you'll no doubt run into at some point in the hobby. 

Size is important. The size of the tank should be determined by a few factors in this order of importance.

The resources you have to make this dream a reality.
Keeping an aquarium is not a one-off purchase. Don't forget about the additional costs to your hydro and water bills on top of maintenance items.

Your personal level of dedication to general upkeep.

If you aren't the type of person who is motivated to take on additional responsibility, then even a fish bowl may not be suitable for you. In fact fish bowls, for their size, are probably the most work in my humble opinion. A properly maintained fish bowl would undergo frequent water changes to battle stagnation and poor water quality associated with having no real filtration system in place. These changes would be completed with properly treated water of the correct temperature so as to cause as little stress as possible for the fish. Not only that, but the fish we tend to keep in these bowls, gold fish, are very messy fish by comparison to others. If you are not prepared to provide proper maintenance read no further. Most gold fish can live for many years. In the proper conditions it would not be surprising to learn that a goldfish was over 10 years old. The majority kept in a fish bowl will never make it that far.

The space you have to place it in your home.

It can sometimes be easy to imagine things in places they might not belong. Do the measurements and make sure it not only fits, but leaves room for the rest of your life to get around it! After having spent some time working in the retail furniture industry, it's incredible to learn how many people really forget to do this. If you are purchasing a large aquarium think about how it will be manoeuvred through your home. Also, if you're not planning on using a for-the-tank stand and instead some other furniture item, keep in mind the weight of the tank when it's full can be quite heavy. Some items sold in today's markets are not the sturdiest!

Also, this can have an impact on the best shape for your tank. There are more and more "alternative" tanks available including below-the-coffee-table styles, "corner" styles and on-the-desk mini tanks all designed to appeal to modern approaches to furnishing the home. These qualities generally come with an increase in price, so if you're operating on a strict budget you may find a more traditional tank offers the most flexibility for stocking with fish while also keeping cost down.

Check out some additional tips on tank placement here.

The fish you intend to keep.

Some fish have special requirements. Often you won't find these more specialized fish at your local fish store, but they are out there. Getting informed about the size of the ADULT specimen is highly recommended. It is a lot easier to sell juveniles for many reasons including required shelf space and their cute, lovable faces for instance! If you have 10 gallon tank with no plans for upgrades, you might want to rethink buying a 2" Oscar. 

A common rule of thumb is the "one inch of fish per gallon" rule. While this rule of thumb may provide some insight for a beginner hobbyist, there is more at work here. Your level of filtration, maintenance and fish requirements make this rule unreliable.

Some fish will dwell at particular levels in the aquarium such as the top or bottom and rarely venture to leave it. These fish will often require particular dimensions more so than gallons. For instance, a catfish that dwells primarily at the bottom of the tank will prefer a tank with a large base and care less about the total depth of the tank. Other fish which are very active or territorial may have quite different requirements.

Once you've selected specimens that interest you, the tank size requirements should be relatively straight forward. Just remember to provide enough space for your specimens. After you add decorations, or if you don't plan on filling the tank to full, remember that this will have an impact on gallons and the overall swimming space. 

Good luck!