Wayne Kasacek, of the Connecticut Department of Agriculture, and Shelton police Sgt. Robert Kozlowsky say most of the 150 confiscated birds were saffron finches and that a few were canaries.
"When the canaries are bred, they will fight to the death," Kozlowsky told CBS Connecticut affiliate WFSB.
Kasacek say some of the birds had previous injuries, including blindness in at least one eye, and may have to be euthanized.
Police say they made the arrests Sunday just as spectators had placed bets and were getting ready to watch the birds fight at a home in Shelton, just west of New Haven. Authorities say they seized $8,000 in alleged betting money.
Saffron finches are small birds that are native to South America.
The 19 people were charged with cruelty to animals and gambling. They include Connecticut, Massachusetts and New Jersey residents.
Police also charged the homeowner, 42-year-old Jurames Goulart, with interfering with officers.