3 sentences

1. 池塘里有许多金鱼在游动。

   chí​táng lǐ yǒu xǔ​duō jīn​yú zài yóu​dòng.

   There are many goldfish swimming in the pond.

   Source: Dong Chinese Dictionary

2. 鱼在水中游动。

   yú zài shuǐ​zhōng yóu​dòng.

   Fish swim in the water.

   Source: Dong Chinese Dictionary

3. 这条小溪清澈见底，鱼儿在水中自由自在地游动。

   zhè tiáo xiǎo​xī qīng​chè jiàn​dǐ, yú'ér zài shuǐ zhōng zì​yóu​zì​zài de yóu​dòng.

   This stream is crystal clear, and fish swim freely in the water.

   Source: Dong Chinese Dictionary