The breeding habits of the barbel are unknown
The Environment Agency is starting a three-year study exploring the movements of one of the east of England's most secretive fish.
Over recent years, the Great Ouse in Milton Keynes and Bedfordshire has become synonymous with barbel but little is known about their movements.
The £50,000 project will try and find out more about breeding habits.
The ancient fish is important to rivers and features on Queen's College, Cambridge University, coat of arms.
The Environment Agency will be working closely with the Upper Ouse Fisheries Consultative Association (UOFCA).
Ian Hirst, fisheries specialist, said: "The popularity of fishing for barbel has grown over the past decade. We are struggling to understand where the young barbel are coming from.
"We hope this study will use local knowledge, feedback and advice from UOFCA members to help us build a clear picture of the barbel in our river and ensure there are plenty of fish for future anglers in the Great Ouse."