The pituitary hangs down from the bottom of the brain and contains hormones which regulate gamete maturity and promote spawning. Removing the pituitary from the brain of one catfish of either sex and injecting it into the body muscle of a similarly-sized female catfish will allow her eggs to completely mature and she can be spawned the next day. For this kind of catfish in particular, it is easier to remove the lower jaw, gills and accessory breathing organs and then have an easier access to remove the lower skull and pluck the pituitary out. By the way, yes, this is brain surgery.