ScienceDaily (Sep. 21, 2011) — An angry glare from the family goldfish might not be the result of a missed meal, but a too-humble abode. Fish in a cramped, barren space turn mean, a study from Case Western Reserve University has found. Ornamental fishes across the U.S. might be at risk, all 182.9 million of them.
"The welfare of aquarium fishes may not seem important, but with that many of them in captivity, they become a big deal," said Ronald Oldfield, an instructor of biology at Case Western Reserve. Why, then, has the welfare of pet fishes been overlooked among the scientific community?
Oldfield is the first to scientifically study how the environment of home aquariums affects the aggressive behavior of ornamental fishes. The results are published in the online Journal of Applied Animal Welfare Science, volume 14, issue 4.
Oldfield compared the behavior of Midas cichlids (Amphilophus citrinellus) in a variety of environments: within their native range in a crater lake in Nicaragua, in a large artificial stream in a zoo, and in small tanks of the sizes typically used to by pet owners.
The study focused on juvenile fish to remove aggressive behavior related to mating. Also, resources such as food and shelter were removed prior to observation to eliminate direct competition.
Along with environment size, Oldfield tested the complexity of an environment and the effects of number of fish within tanks.
The addition of obstacles and hiding places using rocks, plants, or other similar objects can increase the complexity of the aquarium environment.
He found that an increase in tank size and complexity can reduce harmful aggressive behaviors, and make for healthier fish at home.
Oldfield quantified aggressive behavior as a series of displays and attacks separated by at least a second. Displays are body signals such as flaring fins. An attack could be a nip, chase, or charge at another fish.
In aquariums, these behaviors can lead to injury and in extreme cases to death.
Aggressive behavior was not correlated with small-scale changes in either group size or habitat size alone. However, a significant difference was observed in environments sufficiently large and complex: fish spent less time exhibiting aggressive behavior.
"This more natural environment elicits more natural behaviors, which are more interesting to observers," Oldfield said.
And, for the fish themselves, their lives can be vastly improved with these simple changes to their environments.
"If we are going to try to create a society as just as possible, we need to do everything we can to minimize negative effects," Oldfield said.
But why should anyone beyond fish enthusiasts care about fish behavior?
Minimizing negative effects extends beyond the treatment of ornamental fishes. Interactions between humans and other species could apply.
Humans have intimate relationships with a variety of fishes. They provide food and sport for many people. Some are used for decoration, and others are well-loved pets or may become addicting hobbies.
Additionally, conditions for animals in the rapidly growing field of aquaculture and on factory farms are issues of contention.
Oldfield is not trying to support any extreme agendas. "I'm not trying to ban human use of animals- I just think that if we are going to interact with them then we should be as informed as possible."
Relatively simple fish behavior can also serve as a basic model for more complex behaviors.
In the future, Oldfield said, "This study might help us to better understand how human behavior changes when people are placed in different social environments." Violence in prisons might be linked in part to the smaller space and reduced stimuli.
Until then, the 182.9 million ornamental fishes in the United States may benefit from this study. The family goldfish can swim in peace, enjoying the remodeled space.
http://www.sciencedaily.com/releases/2011/09/110922102241.htm
Showing posts with label pet fish. Show all posts
Showing posts with label pet fish. Show all posts
Friday, September 23, 2011
Thursday, September 22, 2011
Warning against freeing pet fish
The release of a single female pet fish into the wild can generate entire new populations, even with no males present, according to new research.
A new study has revealed how the guppy's ability to keep on reproducing has earned the fish its reputation as one of the world's most invasive fish.
St Andrews University biologists, who made the discovery, are now warning pet owners against releasing the fish.
West Indies University experts also worked on the study.
The biologists have confirmed the two most important routes of guppies finding their way into the wild are the escapes of ornamental fish, and deliberate introductions designed to control the larvae of mosquitoes that spread malaria.
In places such as Southern India, guppies are routinely released into water troughs, wells and small ponds for mosquito control.
Although self-contained at first, heavy rains and flooding mean that the fish eventually find their way to streams and rivers where they come into contact with native fish.
"We know that the vast majority of species introduced to a new habitat in this way are unable to survive, let alone establish a population, which left us with a huge question mark."
To try to solve the mystery, the researchers conducted an experiment where single wild female guppies were put into outdoor tanks.
After two years, they discovered that almost all of the tanks contained populations of guppies, each founded by just one female.
Reduced biodiversity
Dr Deacon said: "Sperm storage is an excellent adaptation for living in constantly changing habitats, and it might also explain the guppies' global success.
"Female guppies can store sperm in their reproductive tracts for many months after mating, and this enables single fish to establish populations, even when no males are present.
"We also found that these populations kept all of the important behaviours that wild guppies have, so they would be well-equipped for surviving in a new environment."
"Our study shows why we should be cautious when releasing exotic species.
"Seemingly harmless activities such as a child freeing a few pet fish or a concerned householder using guppies to control mosquitoes, can ultimately contribute to the reduction of biodiversity in freshwater habitats across the world."
The popular ornamental fish, whose native home is Trinidad and the north-eastern fringe of South America, is now present in more than 70 countries worldwide.
The research, published by the journal PLoS ONE, was funded by the Natural Environment Research Council and the European Research Council.
http://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-14972053
A new study has revealed how the guppy's ability to keep on reproducing has earned the fish its reputation as one of the world's most invasive fish.
St Andrews University biologists, who made the discovery, are now warning pet owners against releasing the fish.
West Indies University experts also worked on the study.
The biologists have confirmed the two most important routes of guppies finding their way into the wild are the escapes of ornamental fish, and deliberate introductions designed to control the larvae of mosquitoes that spread malaria.
In places such as Southern India, guppies are routinely released into water troughs, wells and small ponds for mosquito control.
Although self-contained at first, heavy rains and flooding mean that the fish eventually find their way to streams and rivers where they come into contact with native fish.
Dr Amy Deacon, St Andrews University lead researcher, said: "Usually only one or a few fish are released.
"We know that the vast majority of species introduced to a new habitat in this way are unable to survive, let alone establish a population, which left us with a huge question mark."
To try to solve the mystery, the researchers conducted an experiment where single wild female guppies were put into outdoor tanks.
After two years, they discovered that almost all of the tanks contained populations of guppies, each founded by just one female.
Reduced biodiversity
Dr Deacon said: "Sperm storage is an excellent adaptation for living in constantly changing habitats, and it might also explain the guppies' global success.
"Female guppies can store sperm in their reproductive tracts for many months after mating, and this enables single fish to establish populations, even when no males are present.
"We also found that these populations kept all of the important behaviours that wild guppies have, so they would be well-equipped for surviving in a new environment."
"Our study shows why we should be cautious when releasing exotic species.
"Seemingly harmless activities such as a child freeing a few pet fish or a concerned householder using guppies to control mosquitoes, can ultimately contribute to the reduction of biodiversity in freshwater habitats across the world."
The popular ornamental fish, whose native home is Trinidad and the north-eastern fringe of South America, is now present in more than 70 countries worldwide.
The research, published by the journal PLoS ONE, was funded by the Natural Environment Research Council and the European Research Council.
http://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-14972053
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