マダイ仔魚の空気呑み込みと鰾の開腔および脊柱前彎症との関連

概要

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The lordosis frequently observed in hatchery-reared red sea bream, a big problem in the seed production in Japan, is known to be induced in the fish with uninflated swim bladders. Rearing experiments were conducted to determine whether the abnormally developed swim bladders were due to failure in gulping air at the water surface. One tank was sealed with a layer of liquid paraffin and the other with open surface served as a control. Over 90% of the larvae had normal swim bladders at around 7th day after initial feeding (4.2mm in total length) in the control, whereas none was in the sealed tank. On the other hand, the lordosis began to appear at around 40th day after hatching in the fish with uninflated swim bladder and more than 90% of the fish showed characteristic lodosis at the end of the feeding trial of 120 days. Thus, it has been shown that gulping air at the water surface is essential for the initial swim bladder inflation and that the uniflation is closely related to the development of lordotic deformity. The relationship between the nutritional quality of rotifers or rearing conditions such as aeration and swim bladder inflation is also discussed.
日本水産學會の論文