"He had a tent, and had spent the night there," the resident said.
"He had brought along three big rods.
"It is illegal. I wouldn't mind, but you are not far from legal spots where you can get a licence to fish at.
"He had his camera and had set up a tripod taking pictures of what he caught, including a big carp.
"There are 'no fishing' signs on display, he has just ignored them."
The resident added action should be taken against illegal fisherman in the basin, especially as basins are often areas where fish spawn.
Had he been caught the fisherman risked being prosecuted, and could have been hit by a fine of up to £800.
Diglis Basin is part of the Worcestershire & Birmingham Canal, owned by the Canal and River Trust that said it is the latest report it had received.
A trust spokesman said: "No fishing signs have been installed around the basin following complaints from resident boaters and boat owners.
"As there are clearly signs in place and permission hasn’t been given to fish then anyone caught fishing will be doing so illegally.
"We would urge any residents to report anyone seen fishing to Aquavista (who manage operations and enforce the rules) and any reports of antisocial behaviour to the local police.
"Marinas are perfect for spawning fish. Fish will naturally seek out areas that are wider, deeper and areas that provide cover from above.
"These areas naturally attract a lot of fish as a larger space allows for larger fish to grow too, so specimen size fish of all fish species will be present in most marinas and basins.
"Typically, anglers fishing for specimen fish are looking to catch large carp and pike."