In cramped space even fishes turn aggressive

September 23rd, 2011 - 4:54 pm ICT by IANS  

Washington, Sep 23 (IANS) Fish in a cramped, barren space turn mean and aggressive — and a new study says this may have larger implications for human beings.

Relatively simple fish behaviour can serve as a basic model for more complex behaviours. It may explain why violence in prisons might be linked in part to the smaller space and reduced stimuli, says the American study.

“This study might help us better understand how human behaviour changes when people are placed in different social environments,” said Ronald Oldfield, biology instructor at Case Western Reserve University, who led the study.

“More natural environment elicits more natural behaviours, which are more interesting to observers,” the Journal of Applied Animal Welfare Science quotes Oldfield as saying.

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, according to a Case Western statement.

Besides, ornamental fishes across the US might be at risk, all 182.9 million of them, added Oldfield, who is the first to evaluate how aquariums affects the aggressive behaviour of fishes.

Oldfield compared the behaviour 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 used by pet owners.

Oldfield quantified aggressive behaviour 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, this behaviour can lead to injury and, in extreme cases, to death.

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