Leading trainer Ciaron Maher has been fined $300 for not wearing a safety vest when riding a horse at the beach.

Racing Victoria stewards censured Maher when the matter came to their attention via a Twitter video posted on February 14.

Maher was mounted on a horse at Mordialloc Beach without the correct safety gear.

He was also reminded his helmet should be properly fastened and he must wear appropriate footwear.

Credit: AAP