Apprentice Tom Sadler has been fined $500 after finishing second on Testability at Geelong on Wednesday.

Sadler has a listed riding weight of 56kg and had told stewards on race morning he could ride Testability at 55.5kg, taking a claim of 1kg.

But on weighing out Sadler could not get below 56kg, taking only 0.5kg from the filly's allotted 56.5kg.

Trained by his father John, Testability was beaten a long neck by Fast Approaching in the APCO SV Handicap as the $3.40 favourite.

Sadler has struggled with his weight.

Stewards told the apprentice he can't ride under 56kg until he meets with the Racing Victoria medical officer.