The kanji and the word are exactly the same. That means they share meanings as well.
Since this word is made up of a single kanji, it should use the kun'yomi reading. When learning the kanji, you didn't learn that reading, so here's a mnemonic to help you with this word:
Imagine a fish. Now imagine the fish playing soccer, while wearing a nun's outfit. This is a soccer nun (さかな).
This is a fish called "koi."
I'm not good at cutting fish.
In Japan, people eat raw fish.