Tropical Fish Secrets
It's always fun when a guest comes into my home for the first time... you can see their eyes light up like a little kids' and exclaim, "Wow, an aquarium!" as they make a "B-line" for it and proceed to gawk in amazement!
Tropical Fish Secrets

Thursday, May 18, 2006

Public aquaria

Public aquaria are facilities open to the public for viewing of aquatic species in aquaria. Most public aquaria feature a number of smaller tanks, as well as one or more large tank greater in size than could be kept by any home aquarist. The largest tanks hold millions of U.S. gallons of water and can house large species, including dolphins, sharks or beluga whales. Aquatic and semiaquatic animals, including otters and penguins, may also be kept by public aquaria.
Operationally, a public aquarium is similar in many ways to a zoo or museum. A good aquarium will have special exhibits to entice repeat visitors, in addition to its permanent collection. A few have their own version of a "petting zoo"; for instance, the Monterey Bay Aquarium has a shallow tank filled with common types of rays, and one can reach in to feel their leathery skins as they pass by.
Also as with zoos, aquaria usually have specialized research staff who study the habits and biology of their specimens. In recent years, the large aquaria have been attempting to acquire and raise various species of open-ocean fish, and even jellyfish (or sea-jellies, cnidaria), a difficult task since these creatures have never before encountered solid surfaces like the walls of a tank, and do not have the instincts to turn aside from the walls instead of running into them.
The first public aquarium opened in London's Regent's Park in 1853. P.T. Barnum quickly followed with the first American aquarium, opened on Broadway in New York. Following early examples of Detroit, New York and San Francisco, many major cities now have public aquaria. Most public aquaria are located close to the ocean, for a steady supply of natural seawater. An inland pioneer was Chicago's Shedd Aquarium that received seawater shipped by rail in special tank cars. In contrast, the recently opened Georgia Aquarium filled its tanks with fresh water from the city water system and salinated its salt water exhibits using the same commercial salt and mineral additives available to home aquarists.
In January 1985 Kelly Tarlton began construction of the first aquarium to include a large transparent acrylic tunnel in Auckland, New Zealand, a task that took 10 months and cost NZ$3 million. The 110-meter tunnel was built from one-tonne slabs of German sheet plastic that were shaped locally in an oven. A moving walkway now transports visitors through, and groups of school children occasionally hold sleepovers there beneath the swimming sharks and rays.
Top public aquaria are often affiliated with important oceanographic research institutions or conduct their own research programs, and usually (though not always) specialize in species and ecosystems that can be found in local waters.
For a partial list of public aquaria worldwide, see list of aquaria.

Sunday, May 07, 2006

Biological loading

Biological loading is a measure of the burden placed on the aquarium ecosystem by its living inhabitants. High biological loading in an aquarium represents a more complicated tank ecology, which in turn means that equilibrium is easier to perturb. In addition, there are several fundamental constraints on biological loading based on the size of an aquarium. The surface area of water exposed to air limits dissolved oxygen intake by the tank. The capacity of nitrifying bacteria is limited by the physical space they have available to colonize. Physically, only a limited size and number of plants and animals can be fit into an aquarium while still providing room for movement.
In order to prevent biological overloading of the system, aquarists have developed a number of rules of thumb. Perhaps the most popular of these is the "one inch of fish per U.S. gallon" rule, which dictates that the sum in inches of the lengths of all fish kept in an aquarium (excluding tail length) should not exceed the capacity of the tank measured in U.S. gallons (about 7 mm per liter of water). This rule is usually applied to the expected mature size of the fish, in order to not stunt growth by overcrowding, which can be unhealthy for the fish. For goldfish and other high-waste fish, some aquarists recommend doubling the space allowance to one inch of fish per every two gallons.
The true maximum or ideal biological loading of a system is very difficult to calculate, even on a theoretical level. To do so, the variables for waste production rate, nitrification efficiency, gas exchange rate at the water surface, and many others would need to be determined. In practice this is a very complicated and difficult task, and so most aquarists use rules of thumb combined with a trial and error approach to reach an appropriate level of biological loading.

Other nutrient cycles

Nitrogen is not the only nutrient that cycles through an aquarium. Dissolved oxygen enters the system at the surface water-air interface or through the actions of an air pump. Carbon dioxide escapes the system into the air. The phosphate cycle is an important, although often overlooked, nutrient cycle. Sulfur, iron, and micronutrients also cycle through the system, entering as food and exiting as waste. Appropriate handling of the nitrogen cycle, along with supplying an adequately balanced food supply and considered biological loading, is usually enough to keep these other nutrient cycles in approximate equilibrium.


New aquaria also do not usually have the required populations of bacteria for the handling of nitrogen waste. In a process called cycling, aquarists cultivate these bacteria as fish and other producers of nitrogen waste are gradually added to the tank over the course of several weeks. Aquarists use several different methods to jump start this process, including the use of water additives containing small populations of the bacteria, or "seeding" a new tank with a mature bacterial colony removed from another aquarium (such as can be found on gravel or biological filter media).
Other cycling methods that have gained popularity in recent years are the fishless cycle and the silent cycle. As the name of the former implies, no fish are kept in a tank undergoing a fishless cycle. Instead, small amounts of ammonia are added to the tank to feed the bacteria being cultured. During this process, ammonia, nitrite, and nitrate levels are tested to monitor progress. The silent cycle is basically nothing more than densely stocking the aquarium with fast-growing aquatic plants and relying on them to consume the nitrogen products rather than bacteria. According to anecdotal reports of aquarists specializing in planted tanks, the plants can consume nitrogenous waste so efficiently that the spikes in ammonia and nitrite levels normally seen in more traditional cycling methods are greatly reduced, if they are detectable at all.
Improperly cycled aquaria can quickly accumulate toxic concentrations of nitrogen waste and kill its inhabitants.
Tropical Fish Secrets
It's always fun when a guest comes into my home for the first time... you can see their eyes light up like a little kids' and exclaim, "Wow, an aquarium!" as they make a "B-line" for it and proceed to gawk in amazement!
Tropical Fish Secrets