Dey gave a stiff competition to Games record holder Hamizan Amirul Ibrahim of Malaysia before settling for a silver at the Jawaharlal Nehru Stadium five kgs short of the winner's effort. Ibrahim cleared 257kg and Rao lifted 248kg for the bronze medal.
Ibrahim, in the process, claimed the first gold medal for his country while also setting a new Games record of 116kg in the snatch, surpassing his personal best of 115. He lifted 141 in clean and jerk.
The 21-year-old Dey, however, was the surprise element in the event with his career best of 112 in snatch and 140 in clean and jerk.
Although Dey fouled his third attempt in clean and jerk, favourite Ibrahim held his nerve after failing twice to come out trumps in the end.
On the first day on Monday, Games power house Australia has bagged 4 golds to lead the table. South Africa, Canada and Nigeria have won one gold each.
India had mixed fortunes as the hosts recorded impressive wins in tennis, badminton and archery, but the swimmers disappointed.
Women lifters Soniya Chanu and Sandhya Rani Devi provided the Commonwealth Games hosts their first two medals on the first day of competitions while their men's freestyle quartet made history by reaching the final in swimming.
Chanu, favourite for the 48 kg gold medal, settled for silver by clearing 167 kg which was eight kg below what surprise winner Augustina Nwaokolo of Nigeria lifted to win the contest with a new Games record to boot.
Chanu and Nwaokolo were tied with the same clearance of 94 kg in the snatch competition but the latter, who weighed marginally less than the Indian woman, settled the issue in the clean and jerk category.
Sandya Rani took the bronze with a total clearance of 165 kg.
In the pool, the men's 4x400m freestyle relay quartet of Virdhawal Khade, Anshul Kothari, Arjun Jayaprakash and Aaron D'Souza finished sixth in the morning heats to make the evening final where they finished in the same position clocking 3 mins, 27.14 secs.
It's the first time that in swimming the country had been represented in the final in the Commonwelth Games.
"This is really fantastic. We have made history by reaching the final for the first time in Commonwealth Games competition," team coach Pradeep Kumar said.
Two other Indian swimmers - Badrinath Melkote (men's 50m backstroke) and Shubha Chittaranjan (women's 50m butterfly) - qualified for the semi finals by ending up 14th and 16th in the heats. Both were, however, eliminated in the evening semi finals.
But all other swimmers sunk without making a splash. Surbahi Tipre and Arti Ghorpade finished a disappointing 22nd and 24th in women's 200m freestyle.
In men's 400m freestyle heats, Mandar Divase and Ullalmath Gangan finished distant 17th and 18th respectively.
Other Indians to bow out on day one included Beijing Olympian Rehan Poncha and Tarun Tokas (men's 200m butterfly); Priyanka Priyadarshini, Poorva Shetye and Mankiran Kaur (women's 50m breaststroke) and Pooja Alva (women's 200m IM).
India also made a winning start in tennis and table tennis but suffered a major blow in another racquet sport, squash, when their no. one woman player Dipika Pallikal pulled out following a bout of mild fever.
Three other men players - Sourav Ghosal, Harinder Pal Sandhu and Siddharth Suchde progressed to the round of 32.
Indian women, seeded second in the table tennis team event, started their campaign on a resounding note by blanking Sri Lanka 3-0 in Group D at the Yamuna Sports complex.
Mouma Das, Shamini Kumareshan and reigning national champion Poulomi Ghatak won their matches without dropping a game.
The Indian eves have to play against New Zealand and Ghana in the group.
In tennis, Rohan Bopanna outclassed Uganda's Robert Buyanza in straight sets.