Freshwater

Cost
On average, marine fish are much more expensive than freshwater species.
Compare a two-dollar guppy to a queen triggerfish costing several hundred
dollars. A large marine tank could be very expensive to stock, and your wallet
takes a huge hit if anything goes wrong. However, most aquarium hobbyists
think marine species are well worth the extra money.
Beauty and friendliness
Marine fish are generally more colorful and larger than freshwater species. If
you really like eye-popping colors in your aquarium, the marine side of the
hobby will really dazzle you with brilliant yellow tangs, vibrant parrotfish,
and many other spectacular species of saltwater fish. Generally you cannot
keep as many marine fish in the same space as freshwater fish because the
marine fish are larger and generally require more room to move around.
Equipment
Chapter 23: For the Advanced Aquarium Hobbyist
Substrate and equipment are a bit more expensive for the marine aquarium.
Freshwater gravel is less expensive than marine dolomite, and freshwater
lighting costs less than the full-spectrum lighting of a marine reef system.
Many hobbyists are happy keeping only freshwater systems, whereas others
plunge into the brackish and marine worlds. All the information you need is
out there in books, periodicals, pet stores, and on the Internet.
297