Ball partying roach

[Blueavocet]

Brothers, the other evening I was walking the local canal and witnessed something not seen in freshwater by me before. There was a tight ball of roach circling and rolling en mass mid water half way across the canal. I estimated around 50-60 fish of similar size. The rolling motion was leisurely and tight packed. There was no strikes at the ball, no indication of perch or pike marshalling. The roll happened well away from any weed. As they slowly unravelled they proceeded to feed on some fragments of bread left in the water from duck feeding. Now I've witnessed this ball phenomena in fish being hunted but nothing about the demeanour of these fish suggested that. Is this simply play time or partying? What do you think?

[DaceAce]

I have seen this a number of times, usually in hot weather. The roach don't seem to be feeding or affected by any predators. Sometimes some of the roach hang vertically in the water as well.

[Hovis]

I never seen this in reality but I have seen footage that was taken with an ARIS sonar camera on the Norfolk Broads. It demonstrated large shoals of bream swimming round in circles at varying depths, much in the same way larger schools of pelagic species would at sea. Certainly its behaviour that hadn’t been documented before. Raises some interesting points about what triggers this type of behaviour in certain species.

[Dave Burr]

I've seen vast numbers of roach simply hanging, nose down and vertical on a lake. Not seen them for a ball though. Sounds fascinating.

[Blueavocet]

It was certainly a warm day when I saw the roach ball on the canal. I pointed it out to the dog walkers, we must have stared at it for nearly 5 minutes before they peeled off, like wool drawn from a ball, to start feeding.