While Pi is on the lifeboat, the color that predominantly surrounds him is the color orange. Pi even says:
It seems orange—such a nice Hindu colour—is the colour of survival because the whole inside of the boat and the tarpaulin and the life jackets and the lifebuoy and the oars and most every other significant object aboard was orange.
The color orange also signifies his passion and strong will to live. Additionally, the color also symbolizes positivity and optimism. This is presented through Orange Juice—the orangutan that floats near Pi on a nest of bananas and joins him on the lifeboat. The female orangutan reminds Pi of happiness, laughter and friendship.
The fish that Pi catches symbolize his transition from a man who lives to a man who survives. Before being forced to catch, kill and eat the flying fish, Pi was a vegetarian and believed that no animal should be harmed in any way. On the lifeboat, however, Pi must eat to survive, and he feels like a sinner when he kills the fish. He also uses the smaller fish as bait to catch bigger fish and tame Richard Parker's hunger, which technically keeps him alive because the tiger won't attack him when he's full.