A baitboat battery is believed to have caused a fire which ripped through the tackle shop and reception at Bluebell Lakes yesterday afternoon.
About £150,000 of stock in the large tackle showroom was destroyed and the building was badly smoke damaged.
The popular Northamptonshire day-ticket fishery, which boasts five specimen carp lakes and three 50-pounders, attracts anglers from all over the country.
Speaking to Carpfeed at the scene this afternoon, owner Tony Bridgefoot said: "We think it was an angler's baitboat battery which caught fire when it was charging.
"I was out getting birthday presents for my grandchildren and came back to see smoke billowing out of the lights and gutters. The fire brigade arrived 10 minutes later.
"All the stock has gone. I don't think hardly any of it will be salvageable."
The fishery has remained open but can currently only accept cash after the card machine, and the day's takings, were destroyed in the fire.
Two fire crews from Northamptonshire and one from Cambridgeshire were called to the blaze at just after midday on Saturday, March 11.
A spokesman for Northamptonshire fire service said the incident was believed to be accidental and that firefighters were at the scene for more than two hours.
Tony added: "We've got one room we can make into a temporary reception and we hope to be back up and running fully by next weekend, but I think it'll take six months to get it back to anything like this. The hot-water and electric system have all gone."
Also hit by the fire were Bluebell's collection of stuffed fish, including Benson, the famous 60lb-plus common. The case is covered in soot and it is not yet known how badly damaged it is.
"I keep good stock records and without a shadow of a doubt we've lost £150,000 of tackle," said Tony. "I've also lost two racing motorbikes, which will have to be rebuilt at a cost of about £10,000. Then there's the rebuild costs. Luckily, there is no structural damage.
"I'm 61 and I've still got it in me to do it again. I've been flooded twice, but this feels worse because it's not natural like flooding."
On a positive note, Mallard Lake on the site produced its first 40-pounder on the same day.
"We'll bounce back," said Tony.