Spawns in all months, with maximum in spring when adults commonest. Two largest in image, mature adult size, taken in March. Two small specimens, taken in September, are immature juveniles arising from spring spawning; some achieve breeding size (8 mm) and spawn in autumn to produce a secondary peak of spawning. Lengths 4.4 mm, 6 mm, 11 mm & 17 mm. North Yorkshire & North wales. 2015 & 2016.