Marine aquarium

The first saltwater tanks were Venetian glass jars where the Romans kept anemones outdoors, but these systems were very short lived. The Aztec Empire had 10 ponds of saltwater aquariums at Texcoco. In 1846, Anna Thynne maintained stony corals and seaweed for almost three years, and was credited as the creator of the first balanced marine aquarium in London. Personal saltwater fishkeeping began on a wider scale in the 1950s, starting with the basic rectangular glass aquariums (usually 20 gallon), still popular today. Bleached coral along with a substrate of coarse crushed coral were the norm. Algae, including beneficial types such as coralline algae, were viewed negatively and were generally removed. The clean, sterile tank was viewed as the healthiest. During the early days of marine aquaria, saltwater was collected at local beaches. Natural saltwater contains many unwanted organisms and pollutants. Aquarium literature of the time suggests that the most commonly kept marine fish were the percula clownfish, sergeant major damselfish, small, brackish-water pufferfish and scats, jeweled blennies, and blue damsels. Aquariums were equipped with large air compressors, and were heavily aerated and filtered (primarily with undergravel filters, a norm for some time). An ever-growing number of hobbyists experiencing the inconvenience of gathering natural sea water and the concurrent development of analytical chemistry techniques led to research into the chemical composition of sea water. Synthetic salt mixes were developed to replicate the chemical environment of the tropical ocean, including trace elements and salts. This advance made marine fishkeeping popular in areas without access to clean sea water. Air driven, counter-current protein skimmers and reliable submersible electric heaters were invented in Germany. Various advances in filtration included trickle and hang-on filters, both allowing a more natural equilibrium in the aquarium environment. The advancement of fluorescent lighting technologies to provide higher output, along with metal halide lighting, enabled the first reef tanks, making it possible to keep corals and other invertebrates without natural sunlight. More efficient chemical testing allowed aquarists to understand the chemical properties of aquariums. By the 1980s, a biologically based understanding of how to maintain an artificial ocean environment brought more successful and widespread marine fishkeeping. == Modern fishkeeping ==

Marine aquarium components The major components are an aquarium, usually made from glass or acrylic, filtration equipment, lighting, and an aquarium heater. Marine aquariums can range in volume from less than 80 litres, (5000 K tend to be best for growing plants in both the marine and freshwater setting. 10,000 K light appears bluish-white and emphasizes coloration in fishes and corals. Higher up on the spectrum there are 14,000 K and 20,000 K bulbs that produce a deep blue tint which mimic the lighting conditions underseas, creating an optimal ambience for invertebrates and livestock present. Temperature control Most marine aquarium inhabitants are endemic to tropical reefs and waters in Africa, Southeast Asia, and the Red Sea. Marine aquarium temperatures should mimic the natural environment of the inhabitants and are most commonly maintained at . In regions where the ambient temperature is less than the desired temperature of the aquarium this generally necessitates the use of an aquarium heater. In some areas where ambient temperature is greater than the desired temperature, or for coldwater systems, refrigeration devices known as "chillers" are used to cool the aquarium water. Water testing Marine aquarists commonly test the water in the aquarium for a variety of chemical indicators of water quality. These include: • Specific gravity, a relative measure of water density, is normally maintained between 1.020 and 1.024 in aquariums with fish only, and 1.023 and 1.026 for aquariums containing invertebrates. • Salinity should therefore be between 28 and 35 ppt, with the higher values being beneficial in advanced reef systems. • Copper concentration should be measured and not rise over 0.15 ppm • Calcium should be around ~ 400 ppm • Magnesium levels should be ~1250 - 1350 ppm pH can be raised with a commercially available buffering agent or through calcium-rich substrates. A calibrated calcium reactor can assist in maintaining both pH and alkalinity. Using purified water from a reverse osmosis/deionization (RO/DI) unit can prevent KH and pH fluctuation. The nitrogen cycle refers to the conversion of toxic ammonia to nitrite and finally nitrate. While fish waste (urine and feces) and decaying matter release ammonia, the majority of ammonia released (approximately 60%) in both marine and freshwater aquariums is excreted directly into the water from the fishes' gills. Biological (bacterial) nitrification converts the ammonia into nitrite ions, NO2-, and then to nitrate ions, NO3-. Nitrate is readily taken up and assimilated by algae and hermatypic corals. Some nitrate is converted via an anaerobic bacterial process to free nitrogen, but this process is very difficult to maintain. In the recent past, most nitrate, which is less toxic to fishes and most invertebrates than nitrites, accumulated in the water until it was physically removed by a water change. However, many marine aquarists are now employing the use of a special section of the tank or separate tank altogether, called a "refugium." A refugium is, as its name suggests, a sheltered area that shares water with the primary, or display, tank. Refugiums usually contain a deep sand bed to allow anoxic zones to develop within them where anaerobic bacteria can convert nitrate into nitrogen gas, a useful means of nitrate removal. Various types of macroalgae can be grown and harvested from the refugium as another means of nitrate export. As refugiums become more common in marine aquaria, nitrate levels are easily manageable for even the novice hobbyist. Ammonia and nitrite should be tested regularly; any detectable levels (i.e., over 0 ppm) can be indicative of a problem. Nitrates should not exceed 2 ppm in reef tanks, or 20 ppm in fish-only tanks. It is sometimes acceptable to have a small amount of nitrate buildup, as some livestock, especially fish, are fairly tolerant of nitrate. Most corals, while able to assimilate nitrate, cannot be expected to survive, much less thrive, with high nitrate concentrations. Other suggested tests include those for calcium, carbonate alkalinity, magnesium, and other trace elements. It is often beneficial (and necessary) for the aquarist to research the water chemistry parameters for the specific organism that is desired. Acclimation Acclimation is a process that is performed when adding new marine life to an aquarium, particularly for invertebrates, who lack osmoregulation. This process slowly introduces the organisms to the water composition of the new environment, preventing shock resulting from sudden changes in water chemistry. There are several different methods of doing this, including the use of a drip line, or of a measuring cup or other device to slowly mix water from the aquarium tank into a container with the new animal. The drip line or trickle acclimating method is a safe and gentle way to introduce saltwater fish into a new home, and is a fairly simple one to perform. This procedure can be used to acclimate all types of marine as well as freshwater livestock. First, the fish is placed with all the bag water in a bucket or container of sufficient size for the fish to be reasonably covered with the water, and the bucket is then set on the floor next to the aquarium. Using some plastic air line tubing and an air gang valve, a siphon drip line is set up from the aquarium to the bucket. Tank water is allowed to drip slowly into the bucket, using the gang valve to adjust the drip rate, until the water dripped into the bucket equals about two to three times the original volume of the bag water. After testing the pH, salinity, and temperature of the water in the bucket to see if these parameters match that of the tank water, the fish is gently removed and placed into the tank. Water changes Water changes are a staple of good saltwater maintenance. Larger (approximately ) aquariums are much more stable and water changes may not need to take place if the nitrogen cycle has fully established itself in the tank, although this is a controversial statement among aquarists. Water changes are used to maintain balance of calcium, carbonate alkalinity, and magnesium which are rapidly depleted in a reef aquarium, while also maintaining levels of other trace elements as well as removing toxic solutes which may accumulate from many different sources and cannot be removed by even advanced filtration methods. Supplements are needed (such as calcium) when regular water changes alone are not able to maintain adequate levels, particularly those of calcium, carbonate, and magnesium. Water changes involve removing a fraction of the total volume of the aquarium, replacing that water with new pre-mixed saltwater. Pre-mixed saltwater has been dechlorinated and/or dechloraminated—typically with an additive such as bisulfite or through filtering. Water should be brought to the same temperature if more than a 5% change is occurring. Salinity should match that of the aquarium, or be dosed very slowly if altering the salinity. Aging and aerating saltwater (such as in a bucket with a powerhead or airstone) is recommended as good practice to allow the pH to stabilize. Replacement water should be of the same source as the aquarium, whether it be reverse osmosis (RO), de-ionized (DI), distilled or from a municipal supply, in order to avoid drastic changes in water chemistry. In cases where one is replacing a tap water-based salt mix with a reverse osmosis-based salt mix, the replacement water should be added slowly over the course of several hours to avoid sending the aquarium inhabitants into osmotic shock. However, large water changes are not advised under routine circumstances anyway, so this is really irrelevant. Municipal, or tap water, is not recommended for a marine aquarium as it often contains high levels of nitrates, phosphates, and silicates and other dissolved solids which fuel the growth of nuisance algaes, particularly diatoms, which appear as a rust-colored powdery algae and grows in the overabundance of silicates present in all tap water. Water filtered by a four-stage process including mechanical, carbon, reverse-osmosis, and de-ionizing components is recommended as this can provide the easiest route to absolutely pure water. Four- and five-stage RO/DI filtration units can be obtained for as little as $100 and are a cost-effective means of converting tap water into water usable in a marine aquarium. == Conservation ==

Almost all species kept in marine aquaria at this time are caught in the wild, although tank-raised specimens are becoming increasingly common as a viable alternative. The list of marine aquarium fish, such as clownfish that are captive-bred and available on a commercial scale, is increasing. As of a 2019 report, there were nearly 400 known captive-bred species, 46 that were considered commonly available. Much collecting is done in Indonesia and the Philippines, where use of cyanide and other destructive collection methods, while discouraged, is unfortunately common. The majority of live rock is also harvested in the wild, and recent restrictions on this harvest in Florida have caused a shift to Fijian and aquacultured rock. Natural rock, because it is created by coral polyps, takes many years if not centuries to form, and is a vital habitat for countless marine species; thus, commercial-scale harvesting of naturally occurring live rock has been criticized by conservationists. Additionally, many animal species sold to hobbyists have very specific dietary and habitat requirements that cannot be met by hobbyists (e.g. genus Labroides wrasses, the moorish idol); these animals almost inevitably die quickly and have markedly reduced lifespans compared to wild specimens. Often these specific environmental requirements cause improperly housed livestock's color and appearance to be poor. These issues are often downplayed by individuals and organizations with a financial interest in the trade. Hobbyists who support conservation should buy only certified net-caught fish (although ensuring the legitimacy of such claims can be difficult) or captive-raised fish, as well as farmed corals and to support legitimate reef conservation efforts. The majority of corals can be "fragged", whereby a portion of a larger captive coral is separated and can subsequently be raised into an individual specimen, allowing for coral propagation within the domestic aquarium; the trade in frags (i.e. fragments) offers a fantastic opportunity for marine aquarists to obtain new and unique corals while limiting the impact on the natural environment. Rare species and those without a history of being successfully kept in captivity should be avoided. Commercial development Various businesses have commercialized fishkeeping. With the advent of large scale business operations focusing on breeding massive quantities of specimens, marine fishkeeping has become much more widespread than ever before. Perhaps the biggest disincentive to marine fishkeeping, in comparison to freshwater, is the initial setup cost. A reef tank full of coral and equipment can cost in excess of $2,500 US, although a budget-minded home hobbyist could spend less than half of this and still get a satisfactory result. == References ==