The swim bladder status of false trevally (Lactarius Lactarius) was studied from November 2007 to October 2008 in coastal waters of the Oman Sea. A number of 702 swim bladders of false trevally specimens were collected randomly from catch composition of gillnets and bottom trawler. False trevally has an unusual swim bladder, as the first and the second spines of its anal fin are joined that creates a single bone, which is called anchorage bone, and passes from the middle of the swim bladder and 2 lobes of the gonad and connects to the 10th vertebra of the spinal column. Another ending of this bone is wide and reaches anal fin base. This bone is like an anchorage for swim bladder of false trevally and it functions as a center of gravity of the fish in anal fin base. It firms the exterior part of the fish body, so the fish swims through rough waters easily.
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