The practice of keeping aquariums came about in the late 1800's. They were fairly crude. Usually these ancient aquariums only had one side that was made of glass, with the other three sides being made of metal or wood. Most aquariums consisted of fish that were native to the region of its owner simply because of availability. Also most old school fish tanks contained only fresh water fish. The reason being that salt water would corrode the metal frame that held the aquarium together.
Aquariums drastically changed in the 1960's with the invention of silicone adhesive. 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. The flexibility of an acrylic tank will prevent this catastrophe from happening. In addition, acrylic offers more flexibility in design than glass. Acrylic aquariums have been made into everything from coffee tables to gum ball machines.
