A mass fishy event

 It must be the season - I've not seen so many 'love nests' in the river before, and so many fish about, a male courtship conspiracy?

It is believed these bowl-like shapes are made by the male to invite the female to lay her eggs inside the bowl to be eventually fertilised by the male.

Have all the male fish ganged up for this event?

But it looked like there's a laggard, just getting on with its 'nest' bowl.