China says it’s reeling in an unusual catch — alleged spy turtles and sensor-studded fish lurking in its coastal waters.

Beijing’s Ministry of State Security claimed an “undersea current” of espionage is sweeping through its waters in a Friday post on the WeChat social media platform, with foreign powers supposedly casting a wide net to gather intelligence on the People’s Republic.

Turtles, fish and other marine creatures have been outfitted with sensors and sent swimming through sensitive areas, collecting oceanographic data before beaming it to overseas satellites, according to the department.

Foreign powers are alleging using the sea to create “underwater maps” of its coastline as part of an “invisible secret war,” the MSS claims.

The department also said it has recovered surveillance buoys fitted with meteorological and high-precision listening sensors, as well as solar-powered wave gliders — that were capable of capturing real-time port activity and feeding information into a vast “maritime surveillance network.”

“Sensitive data such as ocean current dynamics, water temperature characteristics, temperature distribution, and seabed topography, if stolen by foreign intelligence agencies, will seriously endanger China’s national security, military security, and economic security,” the post warned.

It then goes on to urge researchers, boat owners and fishermen to keep their eyes peeled for anything that looks fishy.

For the past few years, China has been rewarding anglers who help reel in alleged maritime spy equipment.

The payouts reach as high as 500,000 yuan (about $73,000) — making catching slippery spies a very lucrative business.