Geeorb fell and broke his shoulder at the second-last jump, while leading the 4050-metre Hiskens Steeplechase. The eight-year-old, considered one of the best jumpers in the state, was put down on the track.
As the fatal race unfolded, a sky writer above Moonee Valley was spelling out "Ban jumping".
There was one other on-track incident during the race. Tainui Teina, following Geeorb, threw jockey Richard Eynon, but both escaped injury.
A half-dozen protesters went to the scene of Georb's fatal fall as an equine ambulance was about to take the horse's body to a nearby veterinary clinic for a necropsy.
One blocked the path of the ambulance and reports suggest he was forcibly removed by a barrier attendant.
The future of jumps racing in Victoria hangs in the balance after a high death toll marred the start of the season.
Racing Victoria suspended jumps racing in May after three horses died at the Warrnambool three-day carnival in May.
It conducted an urgent review and decided to continue with the sport, subject to changes aimed at reducing the risk and subject to a review at the end of the season.
However, opponents says the death rate is the worst still 1994 - twice that of recent years - and point to previous reviews that have so far failed to solve the problem of horses deaths.
Racing Victoria's jumps review panel will review the circumstances of Geeorb's death on Wednesday.