A fluid delivery device for discharging a fluid having a housing, a piston pump, a biasing mechanism, and a trigger mechanism. The housing has a fluid discharge outlet. The pump has a pump chamber casing for fluid storage, a piston sliding in the pump chamber, a piston plunger, and a delivery channel leading to the housing outlet. The biasing mechanism biases the piston pump casing towards the housing outlet. The trigger mechanism has a catch member and a restraining member movable by a manually actuatable trigger from a cocked to a triggered configuration. The cocked restraining member engages the catch member to prevent movement and fluid discharge. A triggered restraining member disengages from the catch member for movement of the casing towards the housing outlet to discharge fluid from housing outlet.