Keeping tropical fish is a fascinating hobby that has been enjoyed for centuries in different parts of the world. The Romans kept live anemones in saltwater jars, but never succeeded in keeping these beautiful creatures alive for any longer period of time in captivity. They were however much more successful with keeping eels in aquariums, and some sources claim that certain types of eels reached an age of up to 60 years when kept by the Romans. In South East Asia, the first fish keepers had their fish in ponds, not in aquariums. The first domesticated species were probably carps and all of today's fancy goldfish types actually hail from a wild carp that can still be found in Asian rivers and streams.

If you want your fish to thrive like the Asian carps instead of quickly vanish like the Roman anemones, it is important that you take the time to learn the basics about fish keeping and aquarium maintenance before you set up your first aquarium. By obtaining the basic information before you go about, you will save yourself a lot of time, money and effort in the long run since you will be able to avoid the common beginner mistakes. One common beginner mistake is for instance to purchase a very small aquarium, thinking that a large one is much more difficult to manage. The truth is however that the mega-sized show aquariums that you can see in your fish store are easier to maintain than your tiny 5 gallon tank. In a small aquarium, there will be a very little amount of water. If a fish dies in a large aquarium, the pollution will be diluted by gallons and gallons of water. If a fish dies in your 5 gallon aquarium, the carcass may very well pollute your entire tank before you even notice the demise and remove the body from the water. I therefore recommend the beginner aquarist to choose at least a 10 gallon aquarium, and a 30 gallon aquarium is ideal. Avoid extraordinary deep aquariums since they are more difficult to clean. A very deep aquarium can also become a problem if you want to introduce plants to your aquarium, since you might have to install extra strong lights that are capable of penetrating the deep water all the way down to the plants at the bottom of the aquarium.

Filling up your aquarium with water and then promptly add all your fish at once is extremely unadvisable since the aquarium is ready to accommodate that many fishes. An aquarium is actually a miniature ecosystem and fish is not the only thing inhabiting it. Your fish will produce plenty of waste products (chiefly fish poop) that will eventually begin to build up in the aquarium. It is naturally not very healthy for fish to swim around in there own feces, but fortunately enough there exists a certain type of bacteria that can convert waste products from fish into compounds that are less unhealthy. Fish poop contains a high level of ammonia, and ammonia is also excreted via the gills of your fish. Ammonia is harmful to fish and also can turn extremely poisonous if your aquarium experience a sudden change in water chemistry that pushes the pH level above 7.5. If you allow populations of suitable bacteria to establish in your aquarium before you introduce all your fish, the bacteria will convert the ammonia into nitrite. Nitrate is also very unhealthy and high levels of nitrite will kill your fish, but fortunately enough there is another type of bacteria that will love to live in your aquarium and that will change the nitrite into a less harmful compound – nitrate. Nitrate is less dangerous than ammonia and nitrite, but high levels of nitrate will be unhealthy for your fish. There are unfortunately no beneficial bacteria to aid you here, and you must instead remove the nitrate by performing regular water changes. Changing 25 percent of the water once a week is a good rule of thumb, but some aquariums require more frequent water changes. When you are trying to establish your new aquarium or if you are experiencing problems with the water quality, smaller and more frequent water changes are advisable.