A grandmother had a hilarious reaction to a fake fish prank on her birthday.

Granny Shirley Valencia was celebrating her 85th birthday when she requested a sweet and sour fish dish from her grandchildren in Mandaluyong City, the Philippines, on November 14.

Her granddaughter Gianina Donado said the old woman loved to joke around so they thought they would prank her on a special day.

Footage shows granny Shirley trying to slice the toy fish with sauce when it starts moving. She was startled and shouted, ‘Oh no, oh no! It's raw!'

Gianina said: ‘We love our grandma so much and taught us to enjoy life so every chance we get we turn these events into happy memories.

‘We thought of giving her a toy fish, and then her reaction was funny.'

The youngster then took out the real delicious sweet and sour fish after the prank.

Gianina added: ‘She enjoyed the fish, the fake and the real one.'