Different Types of Saltwater Aquariums Saltwater aquariums should generally contain fewer fish than fresh water tanks, because the species tend to grow bigger in size. Marine species may be bred in a captive environment, or caught in the wild. Captive bred species are easier to care for and usually hardier than caught species. It's amazing how much conversation can take place between a two-year old and an aquarium. Let the kids name the fish. Have discussions and ask questions like, what color is that fish? What are the fish doing today? Count the fish. Just be careful with counting. If one of the fish has decided to eat some of its tank mates that could turn into a different type of learning experience altogether. 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. It is recommended that only experienced fish keepers with a real commitment to the hobby attempt a coral reef aquarium. A tank containing coral reef life may require several months of cycling before getting the water just right. The water in a coral reef tank must be regulated for lighting, temperature and ph. Goldfish have a life expectancy of five to ten years. If you do a good job maintaining their fish tank, you should have fun, beautiful fish for a long time. Make sure to feed them correctly and keep their water fresh and clear. When starting any new aquarium, you should get everything in place before buying the fish. Start by replacing the gravel into the tank, followed by refilling the water. Take notice of the temperature once again. Try to add water that is of the same temperature as the original water in the tank. Add your finishing touches with decorative pieces, then carefully move the fish back in. It may take a little while for the fish to adjust to the new water, but after having followed all these steps, you can be sure that your tank is clean and healthy.