Here are some facts:
1) they do not need host sharks. I assure you that they do not need parasites to eat.
2) they grow large, EXCEEDINGLY aggressive. I worked with them in 40,000 g tanks....YES 40,000g tanks. They attacked my hands. They grow HUGE...and IMO no one has any business owning them in a home tank less that many thousands of gallons and why you would even then, I do not know.