An investigation by Cumbria Constabulary's professional standards department found he used police systems inappropriately to gain information about three women.
He also threatened the fairness of a future trial when he attempted to gain favour with another woman when he showed her a photograph of a person who had allegedly attacked her.
Fisher, of Cockermouth, also gave cash and alcohol to one woman who was living in a hostel. He also offered to pay her drug debts in return for sex.
Although the inquiry overseen by the Independent Police Complaints Commission (IPCC) found the relationships were consensual, it concluded that Fisher, who worked in the force's public protection unit, had still abused his position as a police officer between 2008 and 2010.
A jury at Carlisle Crown Court yesterday found him guilty of five counts of misconduct in a public office following a three-week trial. He was cleared of three similar counts.
IPCC commissioner Ms Naseem Malik said after the verdict: "Fisher totally abused his position of trust to target vulnerable women for his own sexual gratification.
"I must praise the bravery of the five women who have stood up in court to give evidence against him. I must also praise Cumbria Constabulary for conducting a rigorous investigation.
"Fisher used police records and the contacts he made totally inappropriately.
"He was a police officer who should have been helping these women by doing the job he was paid to do.
"Instead, he seemed to regard his job as something that gave him opportunities to forge relationships to meet his sexual needs.
"Today's verdict has finally put an end to Fisher's activities."
Cumbria's Deputy Chief Constable Stuart Hyde said: "We are sorry for the distress caused to Fisher's victims while he was a serving police officer.
"We acknowledge their bravery and thank them for bringing his misconduct to our attention so that we could take action.
"We are disappointed by Fisher's behaviour - he abused his position of trust and failed in his role to protect vulnerable members of the community.
"Police officers are not above the law and we expect our officers to conduct themselves lawfully and appropriately, inside work and out.
"By the very nature of their roles, police officers and staff have access to sensitive information, and we take our responsibility to protect that information seriously.
"This case highlights the consequences of abusing that trust and shows how robustly the Constabulary deals with breaches of data protection.
"Fisher's behaviour was not representative of Cumbria Constabulary and he can now contemplate his actions while he awaits sentence."
Fisher was remanded in custody and will be sentenced today.