Fish from Calverton have been used to replenish the River Soar
For more than 70 years Calverton Fish Farm has been at the forefront of fish production and development.
The Environment Agency establishment is funded by the millions of anglers who buy coarse fish rod licences every year.
Coarse fish are those that are caught and then returned to the water by the angler.
It is one of only two such farms in the country, the other being in Leyland, Lancashire.
"Not many people know we're here," said team leader Alan Henshaw. "We like it that way."
Our aim is to stock over four to five years so that eventually the population gets to a stage where it begins to self-sustain
Calverton Fish Farm team leader, Alan Henshaw
The farm was opened in the late 1930s. In the beginning it was owned by the Trent River Board and was essentially a trout farm.
Over the years it changed hands several times until in 1996 the Environment Agency took over.
By this time it had stopped producing trout and was specialising in up to nine species of coarse fish.
No salmon allowed
Coarse fish are those that are caught and then returned to the water by the angler. They include chub, dace and barbel and are not meant to be eaten.
"The big difference between here and central Europe is that our tradition in this country is eating sea fish. The taste of coarse fish is fundamentally different," said Alan Henshaw.
And he defended the fact they are producing fish for sport and not consumption.
"These fish are part of the food chain. Little fish are fed on by big fish. They're fed on by birds and mammals. It's part of a natural, healthy river that contributes to a healthy ecology.
"They're also good as canaries. Often it's an angler who is first to report a pollution because they see some dead fish."
CALVERTON FISH FARM
1930s - Farm built by Trent River Board to produce brown and rainbow trout
1975 - Coarse fish production of carp and roach begins
1986 - Trout production ends with concentration on coarse fish
Only one other course fish farm exists in Leyland, Lancashire
All the running costs of the farm are paid for by anglers. There are around two-and-a-half million coarse rod fishermen who pay for a licence every year.
The money enables the team at Calverton to produce and distribute around half a million fish each year.
The fish are used to re-stock rivers after pollution, to populate newly created fisheries and re-stock areas where water quality has significantly improved.
They spend up to two-and-a half years at the farm before being released.
Those fish leaving Calverton have a good chance of survival. The way they are grown ensures they are fit for purpose in that they can take care of themselves once released into the wild. Alan Henshaw said it is important he makes his fish "street wise".
This is done by bringing up the fish in moving instead of still water so that the fish have to swim to obtain their food, therefore hardening them before they are released in to the wild.
"Our aim is to stock over four to five years so that eventually the population gets to a stage where it begins to self-sustain," he said.
Alan Henshaw checks his chub at Calverton Fish Farm
Together, the six employees at Calverton Fish Farm can boast more than 90 years experience and it seems their services will be in demand for many years to come.
Alan Henshaw believed they will always be needed because of the pressure on rivers from industrial polluters and sewage overspills after heavy rain.
Above all he wanted to encourage a new generation of anglers.
"More of our fish are going to create new fisheries where there's a lack of available fishing. I believe fishing is a force for good. It gets kids into the wild and the fresh air."