There something fishy about a mysterious humming sound that has been heard around Strangford Lough, which has left locals baffled.
The strange sound, which lasted for more than three hours, was heard from around midnight on Friday, November 8.
Since then, readers have been taking to social media to try and solve the mystery for themselves.
From 5G to cars, dead seals, Stephen Nolan and Brexit - the suggestions have been varied.
One reader contacted this newspaper with a new theory. Rachel May said: "It has been widely reported that a strange humming noise coming from water is the sound of mating fish. I hope this finally solves the mystery!"
She was referring to an October 2013 incident, when a similarly mysterious hum kept people in Hampshire awake all night. Residents said the noise was pulsating through homes, forcing some in Hythe near Southampton to leave the area just to get a good night's sleep.
While things have not escalated to that point in Strangford, Ian McConnell - who recorded the noise on video - believes it's the best theory to date.
"I don't think I heard fish. The noise was so loud, it would have had to be a whale at least! Also I'm sure I'd have heard it before if it was something so ordinary as fish," he said.
"But you know, at this stage, I'm pretty sure no one is going to come forward with an answer so mating fish is probably as good as any other explanation!"