Apart from Stalin, senior party members Duraimurugan and Ponmudi Participated in the fast.
Political parties in Tamil Nadu had recently accused the Centre of "betraying" the state by seeking modification of a Supreme Court order asking it to constitute the Cauvery Water Management Board (CWMB).
The ruling AIADMK and Opposition DMK had alleged that the BJP-led government at the Centre made the move with an eye on the Karnataka Assembly polls, scheduled in 2018.
Volunteers of All India Students Federation, affiliated to CPI had staged a protest here and Pro-Tamil and farmers' outfits staged demonstrations in Tiruchirappalli, Madurai and Puducherry on the issue
Stalin had then said DMK would stage a fast on October 7 in this city to condemn the Centre's stand on setting up CMB.