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 generates a great amount of stress for a fish to be captured in the wild and then introduced into an aquarium environment. It is often difficult for them to figure out how to eat. Whenever possible, purchase your fish from a retailer that deals only with breeders or from the breeders themselves. There are five different types of saltwater aquariums.

The first type of saltwater aquarium is the fish only aquarium. This is probably the easiest to care for of the five types, simply because you are only dealing with one type of species. Amongst the saltwater fish there are both tropical and coldwater types. They can't be kept together for obvious reasons. The water temperatures vary greatly. Tropical fish are usually brighter in color, and therefore more appealing to aquarium lovers than the fish available in the cold water variety. Most people are somewhat familiar with a few tropical fish such as the Clownfish or the Angel fish. However, few people have heard of such cold water varieties as, the Shanny or the Tompot Blenny.

The second type of saltwater aquarium is the invertebrate only aquarium. These types of aquariums usually consist of shrimp, prawn, hermit crabs and perhaps even starfish or sea cucumbers. The third type is the fish and invertebrate saltwater aquarium. These are more difficult to maintain than either of the two categories separately. Certain invertebrates feed on certain fish, and the reverse is also true. Therefore, it is important to research the species carefully to ensure that you do not put predator and prey together in the same aquarium. Diseases can also spread more rapidly and are more difficult to prevent and cure in aquariums containing both invertebrates and fish species.

The next type of saltwater aquarium is the coral reef aquarium. Reef aquariums can be tricky to maintain and must be thoroughly researched before attempted. The last category of saltwater aquariums is the specialty aquarium. An example of a specialty aquarium would be an aquarium full of sea horses. Sea horses should not be kept with any other type of fish or marine life, because they are timid and slow eaters. Their food source could easily be taken away by other tank mates. Seahorses prefer to swim vertically rather than horizontally, and should be placed in a tall tank. An octopus and a shark or a ray are other examples of fish that require special needs and would fall into the category of specialty aquarium.

Regardless of which type of saltwater aquarium is chosen, research is highly recommended before purchasing any marine life. Make sure you are willing to make the commitment required to care for a saltwater aquarium.