There is a fish called the blackspot angelfish1，which can change from female to male. No， it cannotdo it by simply wishing to become male. The changehappens for a reason.

The angelfish live in groups. And each group hasone male fish， which is blue in colour， and fourfemale fish， which are yellow in colour.

The male angelfish is the strongest and largestmember of the group. He is the one who protects2and looks after the females and he is like their“security guard3”. When the male dies， the groupneeds a “security guard”. This is when the largestfemale fish in the group begins to change its look.

She begins to grow larger in size. After a week，she starts changing colour， from yellow to blue.Slowly， she begins behaving4 like a male. Two weekslater， black stripes5 on her body. This shows that thechange is done. She is now 100% male！

Another interesting fact about angelfish is thatthey have a job in the fish world. Most of them are“cleaners6”for other fish.

The angelfish are one kind of fish with the brightest color in the sea. You canalso see them at home. People like to keep them because of the interesting patterns7on them. These patterns help them to hide from danger. Often the young ones havedifferent colors from the grown-ups.

At night， when these fish become inactive8， their colors may change. They canbe found in the freshwaters9 of South America， in warm seas and coral reefs10.They can grow up to more than 40 cm. They usually swim by themselves or in pairs.

有一種叫做黑斑神仙魚的魚，它可以從雌性變成雄性。不，它不能僅僅通過許愿就能變成雄性。這種變化的發(fā)生有因可溯。

神仙魚是群居的。每一群有一條藍色的雄魚和四條黃色的雌魚。

雄性神仙魚是群體中最強壯、個頭最大的成員。它負責保護和照顧雌性，就像它們的“保安”。當雄性死亡時，魚群需要一個“保安”。這時魚群中最大的那條雌魚開始改變自己的樣子。

它的體型開始變大。一周后，它開始變色，從黃色變成藍色。慢慢地，它開始表現得像一只雄性。兩周后，它身上出現了黑色條紋。這表明（性別）更改已經完成。它現在是100%的雄性了！關于神仙魚的另一個有趣的事實是，它們在魚類世界里有一份“工作”。它們中的大多數是其他魚類的“清潔工”。

神仙魚是海洋里顏色最鮮艷的一種魚。你也可以在家里觀賞它們。人們喜歡養(yǎng)它們，因為它們身上那些有趣的花紋。這些花紋能幫助它們躲避危險。通常來說，幼魚的顏色與成年的魚不同。

晚上，當這些魚變得不活躍時，它們的顏色可能會改變。人們可以在南美洲的淡水水域、溫暖的海洋和珊瑚礁中找到它們。它們可以長到40 多厘米，通常單獨或成對地游動。

（英語原文選自：pitara.com）

▏Notes

1. angelfish 扁鯊；神仙魚；一種觀賞用熱帶魚

2. protect 保護；防護

3. security guard 保安人員

4. behave 行為；表現

5. stripe 條紋

6. cleaner 清潔工人

7. pattern 圖案；花樣

8. inactive 不活動的；不活躍的

9. freshwater 淡水

10. coral reef 珊瑚礁