Sarpa salpa (Linnaeus, 1758)
地中海に潜む夢見る魚
The Dreamfish Hidden in the Mediterranean
体長約50cm。大西洋東部のビスケー湾から南アフリカ沿岸、マデイラ諸島、カナリア諸島、地中海まで広く分布するタイ科の魚です。銀色から淡い金色の体には、頭部から尾まで10本前後の鮮やかな金色の縦縞が走り、太陽光を浴びると金属のような光沢を放ちます。沿岸の岩礁や海草藻場に大きな群れをつくって暮らし、危険を感じると群れ全体が一斉に向きを変える姿は、地中海を代表する海中景観の一つです。
幼魚は小型の甲殻類なども食べますが、成魚は海藻や海草を主食とする数少ない植物食性のタイ科魚類です。海草藻場では藻類を食べることで植生のバランスにも関わり、沿岸生態系の中で重要な役割を果たしています。また、本種は雄として成熟した後に雌へ性転換する「雄性先熟」の雌雄同体であることも大きな特徴です。
地中海沿岸では古くから食用とされてきましたが、本種には不思議な一面があります。季節や生息海域によっては、有毒な微細藻類などに由来すると考えられる毒素を体内に蓄積し、食べた人に幻覚や幻聴などの神経症状を引き起こす「幻覚魚中毒（Ichthyoallyeinotoxism）」の原因となることがあるのです。この毒性はフグ毒（テトロドトキシン）やシガテラ毒とは異なり、原因物質はいまだ完全には解明されていません。毒性は主に内臓で強いとされ、発生も季節や餌環境によって変化します。
この特異な性質から、海外では「Dreamfish（夢見る魚）」と紹介されることもあります。また、同様の幻覚魚中毒は一部のアイゴ類やイスズミ類など、ほかの植物食性魚類でもまれに報告されています。美しい金色の縞模様を持つサレマは、地中海の海中景観を彩る存在であると同時に、海の食物連鎖が生み出す不思議な現象を象徴する魚でもあります。
Reaching approximately 50 cm in length, the salema porgy is a member of the sea bream family distributed widely from the Bay of Biscay in the eastern Atlantic to the coast of South Africa, as well as around Madeira, the Canary Islands, and throughout the Mediterranean Sea. Its silvery to pale golden body is marked with around ten vivid golden longitudinal stripes running from the head to the tail, creating a striking metallic sheen in sunlight. It forms large schools around coastal rocky reefs and seagrass meadows, and its synchronized movements when threatened are a familiar sight in Mediterranean waters.
Juveniles feed on small crustaceans and other small animals, while adults mainly consume algae and seagrasses. It is one of the few herbivorous species among sea breams and plays an important ecological role in coastal ecosystems by influencing algal vegetation. Another remarkable characteristic is that it is a protandrous hermaphrodite, maturing first as a male before changing sex to become female.
Although the salema porgy has long been consumed as food in the Mediterranean region, it has a mysterious side. Depending on the season and habitat, it may accumulate toxins thought to originate from harmful microorganisms such as certain algae, causing a rare form of poisoning known as ichthyoallyeinotoxism. Symptoms can include hallucinations and auditory disturbances. This toxicity differs from pufferfish poisoning caused by tetrodotoxin and from ciguatera poisoning, and the responsible compounds have not yet been fully identified. The toxins are believed to be concentrated mainly in the internal organs, and their occurrence varies depending on season and feeding conditions.
Because of this unusual phenomenon, Sarpa salpa is sometimes introduced as the “Dreamfish.” Similar cases of ichthyoallyeinotoxism have also been rarely reported in other herbivorous fishes, including some rabbitfish and rudderfish species. With its beautiful golden stripes and mysterious toxicity, the salema porgy represents both the beauty of Mediterranean marine life and the complex relationships within marine food webs.
参考文献
Bellassoued, Khaled. (2014). Toxicity of Sarpa salpa, as related to phytoplankton consumption. 2026年8月12日閲覧
Doochin, David (2016, June 10) “Meet the Hallucinogenic Fish That Can Give You LSD-Esque Nightmares” Atlas Obscura. 2026年8月12日閲覧