Marine aquarium
Marine aquariums house saltwater life with specialized equipment and care.
A marine aquarium is a contained environment for saltwater plants and animals. Hobbyists typically classify these tanks into three types: fish only (FO), fish only with live rock (FOWLR), and reef aquariums. FO tanks often house large or aggressive fish and rely on mechanical and chemical filtration. FOWLR and reef tanks use live rock—coral skeletons that host beneficial bacteria for nitrogen waste processing—as a natural biological filter. Reef aquariums feature live corals, invertebrates, and fish.
Saltwater fishkeeping differs fundamentally from freshwater due to the distinct composition of saltwater and how its inhabitants adapt. Marine systems demand more equipment and stricter water quality monitoring than freshwater setups. Acquiring marine inhabitants is often harder and more costly.
The first saltwater tanks were Roman outdoor jars for anemones, but they lasted only briefly. The Aztec Empire maintained ten saltwater ponds at Texcoco. In 1846, Anna Thynne kept stony corals and seaweed for nearly three years in London, credited as creating the first balanced marine aquarium. Personal saltwater fishkeeping expanded in the 1950s with basic 20-gallon glass tanks. Bleached coral and coarse crushed coral were standard substrates. Algae, including beneficial coralline algae, were removed, as a clean, sterile tank was considered healthiest.
Early hobbyists collected seawater from local beaches, which contained unwanted organisms and pollutants. Common fish included percula clownfish, sergeant major damselfish, small brackish-water pufferfish and scats, jeweled blennies, and blue damsels. Tanks used large air compressors, heavy aeration, and undergravel filters. The inconvenience of gathering natural seawater, along with advances in analytical chemistry, led to synthetic salt mixes that replicate the tropical ocean’s chemistry, including trace elements. This made marine fishkeeping popular where clean seawater was unavailable.
Germany produced air-driven protein skimmers and reliable submersible heaters. Filtration advances like trickle and hang-on filters helped maintain natural equilibrium. Improved fluorescent and metal halide lighting enabled the first reef tanks, allowing corals and invertebrates to thrive without sunlight.
- First balanced marine aquarium credited
- Anna Thynne in 1846
- Earliest saltwater tanks
- Venetian glass jars used by Romans
- Aztec saltwater ponds
- 10 ponds at Texcoco
- Typical tropical temperature range
- 24 to 28 °C (75 to 82 °F)
- Typical temperate temperature range
- 10 to 24 °C (50 to 75 °F)
- Common marine aquarium volume range
- 160 to 400 litres (40 to 100 US gal)
Lore & Background
The first saltwater tanks were Venetian glass jars where 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 basic rectangular glass aquariums (usually 20 gallon). Bleached coral and coarse crushed coral substrate were the norm, and algae were generally removed. Saltwater was initially collected at local beaches, which contained unwanted organisms and pollutants. Commonly kept fish included percula clownfish, sergeant major damselfish, small brackish-water pufferfish and scats, jeweled blennies, and blue damsels. Aquariums used large air compressors and undergravel filters. The development of synthetic salt mixes made marine fishkeeping popular in areas without access to clean sea water. Advances in filtration and lighting enabled the first reef tanks. By the 1980s, a biologically based understanding of how to maintain an artificial ocean environment brought more successful and widespread marine fishkeeping.
Reader's Guide
Marine aquariums are subdivided into fish only (FO), fish only with live rock (FOWLR), and reef aquaria. Fish only tanks often showcase large or aggressive species and rely on mechanical and chemical filtration. FOWLR and reef tanks use live rock, a material composed of coral skeletons harboring beneficial nitrogen-waste-metabolizing bacteria, for natural biological filtration. Reef aquariums display live corals, invertebrates, and fish. The major components are an aquarium (glass or acrylic), filtration equipment, lighting, and a heater. Volumes range from under 80 litres to over 1,200 litres, with most between 160 and 400 litres. Small volumes are more difficult to maintain due to rapid water chemistry changes. Tropical marine tanks are the most common, kept between 24 and 28 °C. Temperate marine tanks, kept between 10 and 24 °C, are more obscure; most colorful species are found in the western Pacific and west coast of North America. Coldwater specimens are usually physically acquired by trolling or seining, though more are becoming commercially available. Live rock provides a buffer to maintain high pH (8.0-8.3), alkalinity, and acid-neutralizing capacity. It arrives uncured and must be quarantined. Dry rock is old live rock that has dried out, used to avoid pests and as an inexpensive alternative.
Did You Know?
- The first balanced marine aquarium was created by Anna Thynne in 1846.
- The Aztec Empire maintained 10 saltwater aquarium ponds at Texcoco.
- Synthetic salt mixes were developed to replicate the chemical environment of the tropical ocean.
- Live rock provides a buffer to maintain pH between 8.0 and 8.3.
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