Abstract
The behaviour of the tompot blenny Parablennius gattorugine was studied by underwater observation and photography on the south‐west coast of the UK over an 11 year period, with >50 individuals identified at two locations by their distinctive skin markings. Observations showed males engaging in rapid swimming behaviour when approached by a female, and younger males using alternative ‘sneaker’ tactics before becoming ‘bourgeois’ territory‐holders. The noninvasive recognition technique also facilitated detailed observations on territory retention (up to 7 years) and agonistic behaviours among both males and females.