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Goldfish Find change troubling? This is the fish for you!

Understanding the saltiness – or salinity – of our world's water tells us about the life within it.

Today's goldfish are the product of a long "fish-story." Their ancestors were reared as food fish in ancient China. During the Jin dynasty (265–420), it was noted that some of normally gray or silver carp had red, orange or yellow color mutations.

The selective breeding of carp was established during the Song dynasty (960-1279). In 1162, the empress ordered the construction of a pond to collect the red and gold varieties.
People outside China's imperial family were forbidden to keep so-called "goldfish" of the yellow variety. Why? Yellow was the imperial color.
Commoners had to stick to the orange version.
Goldfish were first introduced to North America around 1850 and quickly became popular in the United States (US).
In the 1880s and 1890s, goldfish were bred in ponds in Washington and Baltimore. Anyone who sent a request through a member of the US Congress would receive one, along with a glass globe to keep it in.

According to a New York Times article from November 1894, "The business of distributing free goldfish to the people of the District of Columbia has become such a tax on the (US) Fish Commission that it appears they must choose between running a goldfish bureau for Washington exclusively and conducting the legitimate work of the bureau."

Sensitive Subjects

Goldfish are still the most popular pet fish in the US. The oldest goldfish on record lived over 40 years! The main reason why so many goldfish die young is that they aren’t kept in the proper conditions. Turns out, these "easy care" pets can be sensitive to changes in temperature, light, and salinity.

Goldfish thrive at temperatures between 65 and 72°F (18 - 22°C), roughly room temperature or slightly below. However, they can survive at much warmer temperatures... up to 86°F (30°C).
Care must be taken when adding water to a goldfish bowl or aquarium, it should match the existing temperature.
Rapid changes in temperature – such as a building where the heat is turned off for long periods of time– can kill goldfish, especially if the tank is small.
If left in the dark for a long period of time, goldfish can gradually change color until they are almost gray.

Goldfish produce pigments in response to light. This is similar to how human skin becomes tanned in the sun. But too much light can be a problem. Aquarium lights should not be on for more than 12 hours a day, or goldfish may not get enough rest. If it isn’t dark enough for them to sleep, they may hide in plants to seek out darkness.

Please Pass the Salt

Goldfish are "stenohaline": they cannot tolerate a wide fluctuation in the salinity of water. The term is derived from the words "steno" (narrow) and "haline" (salt).

Unlike their namesakes with a big "G"...
...goldfish are pretty bland when it comes to salt.
Research shows that salinities up to and including 6 parts per thousand do not affect goldfish weight gain or growth.
But salinities over 8 parts per thousand produced significant muscle dehydration along with adverse effects on growth and food intake.
8 parts per thousand? That's less than 2 tablespoons of salt in a 1 gallon fish bowl.
Other studies have shown a positive effect of using very low salinities – about 2 parts per thousand – to optimize growth and development of freshwater fish juveniles and larvae.

Did you know that a group of goldfish is known as a "troubling"?

Speaking of troubling, goldfish released to the wild can consume everything from plants to aquatic insects, small snails and crustaceans. Their rooting and foraging behavior can reduce water clarity, affecting vegetation. Goldfish may displace or outcompete native species for food and introduce disease to native fish. Wild goldfish can successfully hybridize with common carp, another invasive fish species in the US.

Hundreds of years ago, a goldfish was the traditional first anniversary gift for men to give their wives. But that's not where the image of a married couple toasting with goldfish ends...

In 1969, Ralph Ryback published the results of experiments on how different kinds of alcohol affected goldfishes’ ability to learn. Turns out that goldfish swimming in a bourbon solution are more impaired than those splashing around in vodka.

Salt is essential. Circulating through our bodies and our seas, it impacts the health of organisms and our planet.

NASA observes salinity from space. Monitoring sea surface salinity patterns provides important clues about changes in our environment.

A narrated world tour of salinity patterns based on data from NASA's first salinity-sensing satellite, Aquarius/SAC-D.

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