Yes, bristlenose plecos will eat fish eggs. These bottom-dwelling fish are opportunists, so they will certainly consume fish eggs and even fry when given a chance. If you keep your bristlenose plecos in a community tank, you’ll need to keep any other pregnant or spawning fish in a separate tank.
However, bristlenose plecos will not eat their own eggs or young. First-time parents might sometimes try to eat several of their eggs and babies, especially if they don’t get enough food, but they won’t eat every single one of their babies.