The unique thing about a salt water fish aquarium is that it actually replicates the natural environment that you would find in the deep, tropical ocean. There's nothing wrong with freshwater fish, but saltwater have such a unique ecosystem and come in so many wondrous varieties that the two simply cannot be compared. Exotic salt water fish may be more difficult to care for than their fresh water relatives, however, because they have less tolerance for fluctuations that can occur in a closed environment.
A salt water fish aquarium should be able to operate as a self-supporting ecosystem if it has been set up properly. All of the elements that exotic salt water fish would find in nature must e present in the replicated environment if they are to survive. Keeping saltwater fish is a bit of a balancing act, which includes monitoring and maintaining specific parameters to keep the entire system stable. The deep ocean is actually a much more stable environment than people usually think, and the saltwater fish need that kind of atmosphere to survive.
Since exotic salt water fish evolved in the ocean, they do not have the physical ability to adjust quickly to radically changing conditions. Changes occur in the ocean slowly, so any change in the salt water fish aquarium that occurs too quickly can be deadly. A quick drop or rise in the temperature of a salt water fish aquarium, for example, can cause the fish to fall ill. There are many other factors to consider in the proper function of the ecosystem. A typical reading for some of these parameters might be:
* pH: 8.2 Nitrates: < 20ppm for salt water fish and < 5ppm for invertebrates
* Salinity/specific gravity at 77F (25C) with a corrected hydrometer: 1.022
* Temperature: 77F (25C)
* Alkalinity: 3.0
* Calcium for reef keepers and invertebrates: 400-450ppm Ca++
Saltwater fish require a very unique and specific environment for their survival, and keeping it exactly at the right level is important.
