Freshwater Aquarium Fish

A Quick Guide to Freshwater Aquarium Fish
 
Freshwater aquarium fish are pretty much what everyone thinks of when they think of a household aquarium. These freshwater aquarium fish include your Catfish, Goldfish, Eels, Knifefish, Loaches, Puffers, etc. Freshwater aquarium fish come in a vast array of shapes, sizes and colors, and can add a sense of wonder to any home. Especially if you happen to own cats.  If this is the case, also prepare yourself for a modicum of excitement, and to have to rabidly defend your fish for a few weeks, until the feline part of the family gets the idea.
 
Fish are delicate creatures (not delicacies, as your cat believes) and are unable to protect themselves from their immediate environment the way animals on land can. That said, temperature and chemical changes in the water can kill them very easily. 
 
Temperature wise, cold climate fish are somewhat hardier than tropical and salt-water fish. They can subsist in temperatures ranging from just above freezing, to seventy-five degrees Fahrenheit. Tropical fish, as the name implies, cannot deal with water that is too hot or too cold, and their water needs to be kept somewhere between seventy-five degrees and eighty-five degrees Fahrenheit.
 
Another thing to consider when caring for freshwater aquarium fish is the toxicity of the water. More often than not, you'll have to take great pains to overcome tap waters initial toxins--chlorine and chloramines. There are many easy-to-use kits on the market which neutralize these chemicals, but you still need to consistently monitor the levels of these chemicals in your freshwater aquarium. Also, as your fish go about the business of living, they will produce ammonia which must also be treated out of the water.  Every so often, the walls of your freshwater aquarium will require some good old fashioned elbow grease.
 
On the note of ammonia, your aquarium will also require a good filtration system. Water filtration is the beating, pulsing heart of a healthy aquarium. Without it, your freshwater aquarium fish would slowly choke on their own bile. There are scores of different filtering systems out there, but the method I found most effective was an under-gravel filter, backed up by a foam filter.
 
Armed with the advice above, and a little preliminary research about the specific type of fish you're buying, you should be well on your way to keeping a handful of sea critters alive. At least for a few days.