The most important tool in anyone's armory of aquarium supplies is your testing kit. This vital equipment allows you to make sure that the water in the aquarium tank is safe and contains the correct level of chemicals necessary to ensure the health of your fish. There are a few various chemicals you should regularly test for, depending on what species of fish you keep in the tank. An aquarium containing saltwater fish and coral will demand a much more rigorous testing regime than a simple freshwater tank containing less sensitive fish.

The most basic testing kits will test the pH levels in the tank. This is very important to know so that you can maintain the necessary pH level for whatever species are in the tank. A more expensive water testing kit will contain methods of testing the water for hardness, nitrate, ammonia, and oxygen. These are all things that should be closely monitored, as an increase in either one could be disastrous to your fish. Regular testing is a vital part of aquarium care, so make sure that you buy all the necessary equipment right from the very start. The water should be prepared before fish are even introduced.

Correct water temperature of your aquarium tank is also important to the health of your fish so you will need to buy a thermometer. If you intend to establish a saltwater tank you will also need a a hydrometer. These make it possible to check the level of salt in the water. Like all the other elements of the water in your aquarium, the salt level needs be precisely balanced. You should keep the proper marine salt close by at all times in case your salt levels fall below tolerance. This might not seem as important as some other elements but fish are very fragile and are sensitive to these changes in the water.