Uttaradit Governor Sathienpong Maksiri chaired the ceremony, in which the fish and prawns were released from100 long-tailed boats among islets in the 160,000-rai reservoir.
Sathienpong noted that people in the communities around the reservoir have been making a living catching the fish and prawns in the 45 years since the dam was built.
The Uttaradit Fishery Office hatched and nurtured the new population ready for release.