In Fantastic Beasts and Where to Find Them, we learn that:
The creation of Basilisks has been illegal since medieval times, although the practice is easily concealed by simply removing the chicken egg from beneath the toad when the Department for the Regulation and Control of Magical Creatures comes to call.
However, since Basilisks are uncontrollable except by Parselmouths, they are as dangerous to most Dark wizards as to anybody else, and there have been no recorded sightings of Basilisks in Britain for at least four hundred years.
- Voldemort is a Parseltongue, who is specially proud of his connection to snakes;
- Voldemort successfully controlled a Basilisk as a teenager.
- Creating a Basilisk is supposedly a very simple task involving a chicken egg and a toad.
Not only would having Basilisks at his beck and call, be an extremely effective weapon and terror tactic, certainly a Basilisk!Horcrux would theoretically at least, be a better idea than Horcrux!Nagini (almost immortal natural lifespan, plus way better natural defenses against attackers).
So did Voldemort ever try creating more basilisks on his own? If yes, what happened to them? If no, why not?