Long Island cops uncovered a slithering nightmare Thursday when they raided the home of an unlicensed-reptile dealer — and found his garage packed with 850 snakes.

The Suffolk County serpent storehouse contained an estimated half-million dollars in snakes. The boa constrictors, pythons and hog-nose snakes were neatly packed in bins, well fed and ready to be sold to buyers over the Internet, sources said.

“I’d never seen so many snakes in one place before, even in a zoo,” said Ken Gross, chief of Suffolk County’s Society for the Prevention of Cruelty to Animals.

The snakes were being kept by Richard Parrinello, 44, at his home on Auborn Avenue in Shirley, authorities said.

Parrinello — who is a Brookhaven Town animal-control officer — runs an Internet business called Snakeman’s Exotics, which offers serpents to collectors, according to the firm’s Web site.

“All animals are guaranteed to arrive Healthy and Sexed properly!” the company boasts.

Despite the large volume of snakes in the garage, they were all in good shape, officials said.

“We were called to see whether there was any animal cruelty or neglect, [but] the animals appeared to be healthy and well cared for,” Gross told The Post.

In addition to the snakes, SPCA officials — along with those from the state Department of Environmental Conservation and the US Fish and Wildlife Service — recovered turtles and turtle eggs, and at least three tarantulas, officials said.

The crass menagerie was uncovered when the officials served a search warrant at Parrinello’s home as part of their probe into possible animal cruelty.

Although the snakes were treated well, the Burmese pythons are prohibited in New York. The 6-foot-long crawlers are among the five largest breeds of snakes in the world, and hail from Southeast Asia.

They will be relocated to a snake sanctuary in Massachusetts, officials said.

Dave Moran, deputy town attorney for Brookhaven, said that Parrinello will be allowed to temporarily keep his legal snakes, as well as his turtles, turtle eggs and spiders. But he must work out a plan to get rid of his reptile jungle soon.

“He cannot keep them in connection with his business, and I don’t think he’s going to keep them around and say, ‘They’re my pets.’ We’re not going to buy that,” said Moran.

Parrinello, who is married with children, was hit with two violations — one for improperly converting his garage, and another for illegally running a business at his home.

After the raid, he declined to comment, and demanded reporters leave his property.

Town officials got wise to Parrinello’s entrepreneurial sideline as part of an ongoing worker’s- compensation fraud probe that began after he stopped working in May, allegedly due to carpal-tunnel syndrome.

Officials did not say how prolific Parrinello’s snake-selling business might have been.