Usually when people see or think about an aquarium, their only thought is on the fish in the tank.  A glass tank filled with water, fish, and maybe a plant or two.  However, there is quite a bit more to it than that.

The most successful people with their tanks consider the whole ecosystem of a freshwater aquarium.  They understand that the aquarium is not just water, fish, and plants but rather all of the contents are one single living system.

Approaching the set up and maintenance of a freshwater aquarium in this way makes you to treat each component like a part of the whole picture.  When it is time to add some fish, stop and think about how that may affect the other fish, the plants, and the water quality.  Everything that gets added or taken out of an established aquarium can have a compound effect that bears consideration.

A healthy aquatic ecosystem will strike the right balance of fish and plants.  It will be receiving the proper amount of light.  The filter will be keeping dirt in check and the all important nitrogen cycle will be operating smoothly.

The nitrogen cycle is a sometimes overlooked but crucial aspect of any healthy aquarium.  The key to the cycle is the beneficial bacteria that live in the filter as well as in the gravel on the bottom of the tank.   These bacteria “eat” the fish waste and leftover food converting harmful ammonia and nitrites into harmless nitrate that feeds the plants.  The plants use the nitrate and with proper lighting, photosynthesize thus releasing oxygen into the water.  The fish use the oxygen to breathe and they in turn release carbon dioxide that the plants use in photosynthesis and the cycle continues.

Knowing about this cycle and the importance of keeping it in balance can then help you decide what to add to the tank.  It should be obvious that it would be potentially very bad to add too many fish at one time, it would create too much waste, the bacteria couldn’t handle all of it and the ammonia levels in the water could shoot up.   A sudden spike in ammonia levels could kill both the new and the old fish so it is very important to do things slowly when it comes to adding more fish to the tank.

Every inhabitant in the tank uses one substance to create another that is in turn used by something else and so on through the cycle.  So with a healthy aquarium ecosystem, all living things are in balance, the water chemistry is optimal, and the whole aquarium benefits.