10. Adding Fish to the Aquarium
After your aquarium is operating, check the functioning of your equipment and the water conditions again, adding a water conditioner to provide an "aged" water effect and to give the fish a protective coating. The temperature of the water should be 75 degrees F (24 degrees C). If everything is fine, buy your first few fish.
There are two common methods used to introduce fish into the aquarium. One way is to transfer the fish into glass jars, then float the jars in the aquarium for 15 to 20 minutes. Make certain the jars do not have too much water in them. Add small amounts of aquarium water to each jar every few minutes. After the water temperature in the jar is the same as in the aquarium, pour the fish into a net and release into the aquarium. Do not pour water from other tanks into your aquarium, as it may introduce unwanted organisms.

The second method uses the plastic bags in which the fish are usually transported from the store. Use the same floating techniques as above, making sure there is plenty of air in the bag so the fish do not suffocate. Do not allow the bags to collapse.

Although they appear tedious, these methods will reduce the chances of initial shock to your fish in their new environment. The reason for introducing only a few fish at first is to initiate the nitrogen cycle. This cycle takes 20 to 25 days to stabilize, and more fish should not be added until the nitrite level has dropped to a safe level. Use a nitrite testing kit to determine the proper time.

11. Covering the Aquarium
Place the cover plates securely on top of the aquarium to protect the fish and prevent them from jumping out. Turn on the aquarium light.

12. First Feeding and Control
It is advisable not to feed your fish until they have adapted themselves to their new environment (one to two days). Watch your fish closely. If they are hiding in corners, "standing around" or showing pale colors, it is possible that something is out of order. Recheck the following:
    *Is the temperature correct?
    *Was the water too fresh? (Was a water conditioner added?)
    *Are the lights and color of the gravel too light?
    *Do the plants offer enough hiding places for the fish?
    *Are the fish healthy?