Fisher qualified in fifth place and lined up in the middle of the second row for the start of the first race on Saturday.
But he lost a couple of places at the start dropping to seventh and then on lap six fell back to eighth when Dan Stamper made his pass stick.
On the penultimate lap he had to contend with the back markers and didn't get the smoothest passage through them which allowed David Grace to take the advantage and Fisher took the chequered flag in ninth position.
Starting the second race from the fourth row Fisher got a clean start and held sixth on the first few laps but as the race wore on he lost ground and was running in eighth place when the red flag ended the race on lap nine.
He was placed on row six for the start of the final race with a lot of work to do to get on terms with the leading group. But he made up places from 18th to 12th on the first lap and chipped away at the opposition, taking up ninth place on lap three.
He was making inroads into the group some way ahead and on the penultimate lap he caught and passed Andy Smart to take up eighth place.
But with only one lap remaining he was too far away from the next rider to progress further and ended the race in eighth position.
Fisher said: “I had no feel for the bike all weekend. The team put new tyres on but it didn't make any difference, I was not alone as a few of us were suffering with the same thing.
"I am not sure what the problem is but we have a few weeks to check the bike over before the next race so hopefully we will be back to winning ways at Croft.”
With the points accrued at Donington, Fisher is now joint fifth in the rider standings on 89 points. The team has a four week break now and will reconvene for round four at Croft Circuit in North Yorkshire over the weekend of June 10/11.