THE bomb squad was called out when an explosive device was found by police in a car.
But it was later accepted the device, made out of a firework and other items, was to be used to stun fish.
The plan was to use it by detonating it in a river, stun the fish, and collect them when they came to the surface.
But police saw David Parry, 26, and another man at Frith between Mold and Wrexham, and found the device beneath a car seat.
It was placed in a field and the bomb squad was called out to ensure it was safe, Flintshire Magistrates Court was told.
Parry, of Arfryn, South-sea, Wrexham, admitted possessing an explosive substance for the purpose of taking or destroying fish under the Salmon and Fresh Water Fisheries Act.
He was fined £200 with £55 costs - and was fined a further £105 after he admitted personal possession of amphetamine and cannabis.
Prosecutor Justin Espey told how police officers in an unmarked police car on the B5101 outside Frith saw the defendant and another man in a vehicle and stopped and searched them.
The drugs were found but also recovered was a device which included an altered firework, an aluminium can cut at both ends containing a hard, solid object, and a lead weight was tied to it.
Parry told police: 'We chuck it in the water and the fish come up.'
Arrested and inter-viewed, he said he and another man had been given the device to use for fishing and explained it would have to be detonated in water to kill fish nearby.
Both men had been somewhat vague about the man who had given it to them, Mr Espey said.
Forensic analyses showed it was an explosive device capable of stunning and killing fish.
Defending solicitor Catherine Jagger said there was no suggestion her client had been responsible for manufacturing the device.
It had been found under the driver's seat of a car which did not belong to her client but Parry accepted the device had been given to both of them and accepted his responsibility.
The item had not been used and would not have been used until the following day if the police had not intervened.
Miss Jagger said the previous day her client had been in the Moss Valley near Wrexham where he and another man had been fishing.
They had been approached by a man who said he was going to use the device in the river but Parry had told him not to do so because there were so many people about.
The man eventually agreed but gave the device to them.
It was basically a firework in a tin which was intended to stun fish.
They would then come to the surface and they would be able to catch more fish than he would using a rod and line.
Parry appreciated its use was probably illegal, just as he knew the use of maggots was illegal in some fishing areas.
The defendant, who was now a regular user of drugs, had become something of a hermit, was living with his parents, and did not claim benefits.
But he appreciated he should claim the benefits he was entitled to and he could then also pay a fine imposed by the court.
Miss Jagger said his arrest had been something of a frightening experience for her client because the bomb squad had been called out.