You may want to allow the tank to run and filter with decorations and any plant life for a few days before introducing the fish. Be sure to clean the decorations and any substrate thoroughly before adding them to the aquarium. Live plants are highly recommended in new aquariums as they will help to generate the good bacteria necessary to reduce the amount of ammonia in the tank. Good lighting and a strong and efficient filter are a necessity. The tank should only be lit for about 6 hours a day. The more lighting, the more algae will form. You can buy a timer from the pet store to make sure the light is on at the exact time each day. Otherwise the lighting could range from day to day and algae will form. Lastly, check the manufacturer's recommendation on filters and change them accordingly. Filters collect any fish waste or left over food. They can't function properly unless they are clean. Introduce hardy fish to a new tank. These fish can withstand higher nitrite levels that are present in a new aquarium. Catfishes are the ideal candidates for community tanks because they inhabit niches and shelters on the bottom not occupied by other aquarium inhabitants. They generally get along well with all types of fish. Only in combination with some larger Cichlids can there be a problem as the Cichlids tend to extend their territorial claim to the entire tank. Be sure not to clean the filter too thoroughly as it contains helpful bacteria that aids in stabilizing the chemical balance in the tank. During the monthly cleaning, scrape and remove all algae from the surface of the tank. If you find you are having a significant amount of algae, consider adding an algae eater to the tank. Watch the tank for cloudiness and check the temperature and P.H. of the water. If all is clear you may add a few hardy fish. It is important to choose fish that can withstand high levels of nitrites and ammonia, because these levels are always high in a new tank due to the nitrogen cycle. Debris in the tank from fish excretions help to generate the good bacteria that is needed in order for the fish to survive.