Metal frames became obsolete and more people started to keep salt water fish and invertebrates. More recently glass tanks have become less frequently used due to the flexibility of acrylic. Literally flexibility! Acrylic aquariums are far more for forgiving than there glass counterparts. If a heavy object strikes a glass tank, it will almost certainly break. Otherwise you can use regular water, making sure it is at the correct temperature, and add in chemicals to remove chlorine and other unwanted chemicals. Maintenance is a necessity and you will need to clean your tank at least once a month. It is best to try to clean the tank as often as every two weeks however, don't over clean your tank or you will remove some of the beneficial bacteria. Some of the most common are Button Polyp, Yellow Polyp, Hairy Mushroom Coral and Bullseye Mushroom Coral. Make sure when adding your coral, it is attached to the live rock at the bottom of the tank. Wait another 2 weeks. Don't get frustrated... you're almost there! During the eighth week, you can add Aquacultured Coral such as Pumping Xenia, Starburst Polyps and Spaghetti Finger Leather Coral to name a few. Debris in the tank from fish excretions help to generate the good bacteria that is needed in order for the fish to survive. Since there are currently no fish in the tank this will take some time. It usually takes about four to six weeks. Once you have purchased your fish, let them float on the surface of the tank in the bag for about fifteen minutes. These fish were usually kept for short periods of time, and were used as a food source. Home aquariums were generally kept only in coastal towns where the fish were readily accessible. Today, however many things of changed. We wouldn't dream of dipping a net into an aquarium and frying up the family pet for dinner. There are things that should be done daily to care for fish and some things that need only be done weekly or bi-weekly. Daily maintenance of an aquarium is fairly minimal. Look at the fish every day to make sure they appear to be overall healthy and happy. This may seem silly, but the main cause of sickness in fish is stress.