Is it illegal to take home coarse fish and eat them

I am a keen angler and fish throughout the entire year. I'm a big
believer in returning fish as quickly as possible with the minimum
amount of disruption and distress towards the fish. But...
A work college asked if i ever took my catch home to eat, which i
replied absolutely not. He then asked is it against the law, and i
said, well..

So i started to do some research on the subject and i can't find
anything which states you can or can't take fish home to eat. From
rivers that is. The only thing I've found out is that it's illegal to
fish using crayfish as bait, and you can't take fish from private
waters, i.e. poaching.

Maybe there are byelaws for particular areas? Maybe you can take
certain types of fish home, perhaps eels? What about live bait? Can you
fish for say, small roach on rivers and use them in the same area for
live/dead bait? If you can take fish home then what about clubs who
"own" that section of water. Do they have rights to stop people
taking fish home to eat? If anyone can point me in the right direction
then please let me know.

I would like to point out that i'm not advocating or trying to promote
the idea for taking fish home. I'm just curious.