LitCharts assigns a color and icon to each theme in The Hungry Tide, which you can use to track the themes throughout the work.
Language
Man vs. Nature
The Human Cost of Environmental Conservation
Idealism and Theory vs. Practicality and Action
Summary
Analysis
Piya finishes her preparations just after dark and decides to go to bed before dinner. She makes herself some Ovaltine and then goes downstairs, where she finds Nilima. Nilima greets her in Bengali and then apologizes. Piya explains why she never learned Bengali: Piya's father believed Indians don't travel well because they remain fixated on home, so he always spoke English to her. She says her parents spoke Bengali to each other. When they fought, Piya made them translate their messages to English or she refused to act as a go-between. Nilima is silent for a moment before remarking on how sad Piya's parents' marriage sounds.
The reasons why Piya never learned Bengali show again that tone and intent are just as important—if not more so—than the words themselves. As a child, asking her parents to use English was a way for Piya to feel as though she had some degree of power in her own home. Piya's father's insistence that Indians abroad fixate on India again brings up the power of his gamchha to keep him connected to his roots, given that he never got rid of that one item that tied him to home.
Active
Themes
Nilima says that when Kanai came to stay, it meant a lot to Nirmal to have someone to pass on his words to. Kanai never returned after that one visit. Nilima shrewdly says that Kanai is very selfish and it manifests as being driven and often alone, though she warns Piya that Kanai likes women, is "fast," and she should be careful.
Nilima's comment about how much Kanai's visit meant to Nirmal offers some explanation of why Nirmal left his notebook to Kanai. He possibly felt that as a fellow lover of language, Kanai may be more interested.