A HUGE clean-up was under way in Perthshire yesterday after 55 tonnes of farmed trout were lost in a poisoning attack.

Westmill Trout Farm in Rattray, part of the UK's largest hatchery operation, lost rainbow trout worth around #100,000 after a feeder stream was contaminated with the cyanide-based poison Cymag.

Contractors were brought into the farm yesterday to bury tonnes of dead fish.

Cymag, a poison often used by poachers, was put into the lade leading from the River Ericht to the trout farm.

The scale of attack suggests it was an act of vandalism.

The owner of the fish farm, Mr Richard Haldane, of Cloan Hatcheries in Auchterarder, said: ''It is appalling. This seems to be a particularly pointless thing to do, because we do not make enemies. We have not done anything to upset anybody locally, so why has this has happened?''

As soon as the poison entered the pond, many of the fish were starved of oxygen and perished. Within seconds the weight of dead trout smashed the screens at the outflows, allowing fish that were still alive to escape into the River Tay.

Mr Haldane said: ''Cleaning up is a massive operation. You can imagine just how difficult it is to remove a tonne of fish from underwater and there are fish lying on the land as well.''

He added: ''It is a big blow, but we shall survive.''

Yesterday, anglers lined the banks of the Ericht as they attempted to hook some of the escaped fish.

Police are now investigating the incident. One theory is that local poachers with an axe to grind may have been responsible.

Constable Roddy Wood, of Blairgowrie police station, said: ''We are following a definite line of inquiry.

''We think this may have may been some form of grudge by local poachers.

''But no 'good' poacher would have done this. A 'good' poacher normally puts a bit of cymag in a sock so that you only kill three or four fish. This is just vandalism. This is not someone just taking a fish for the pot. Someone has just thrown a whole tin in the river for the sake of a few fish.''

He added: ''These are just mindless idiots who don't think about anything.

''Heaven help any hotel that buys any of these illegal fish as we will prosecute it.''