Something I copied out from this site: https://biomedicalsciences.unimelb.e...kes-pseudechis
"A positive and widespread piece of folk wisdom about red-bellied black snakes is that they eat the more dangerous eastern brown snakes (Pseudonaja textilis), and thus if red-bellied black snakes are present, brown snakes will not be. Unfortunately, this is not entirely true – whilst red-bellied black snakes will certainly eat brown snakes (and other snakes), and thus may contribute to keeping their numbers down, the presence of black snakes is no guarantee as to the absence of brown snakes. It is an interesting fact, however, that black snakes appear immune to the venom of brown and other venomous snakes, as they have been observed receiving multiple bites from their toxic prey without apparent ill effect."