Two armed raids where the robber wore a dust mask and surgical gloves and made his getaway on a bicycle are being linked by police.
The gunman threatened staff in a shop unit with a shotgun
The first was at a One-Stop shop in Sussex and the second, a day later in Kent, took place at a fish farm.
Sussex Police confirmed that the forces in the two counties were linking the robberies and dealing with them as one investigation.
Both armed robberies took place over the bank holiday weekend.
At the fish farm and 42-acre nature reserve in Hastings Road, Hawkhurst, owner Tony Wilkinson said: "If he's done it twice then it's likely he will do it again.
"I would warn everybody that's in this situation - out in the country with a garden centre or a wild animal centre - to beware of somebody coming in and looking suspicious."
The farm has several shop units and the man, armed with a shotgun, threatened staff at the Japanese koi carp centre and took cash. He then put his gun in a plastic bag and left on a bike.
He had walked out of the anglers' shower room wearing a mask and gloves at about 1730 BST on Easter Sunday.
A day earlier, an armed robber with a white carrier bag targeted the One-Stop shop in Turkey Road, Sidley, taking cash.
At the farm, the robber was described as white, aged between 43 and 47, about 5ft 8in tall, and wearing a hooded raincoat and dark trousers.
The offender at the shop was described as aged between 20 and 30, between 5ft 8in and 5ft 10in tall, tanned, of medium build, and wearing dark clothing.