The tail is absent from sunfish. They're sometimes referred to as "gigantic swimming heads" (which seems a bit rude)
Their dorsal and anal fins are merged into a rudder-like device called a clavus in place of a tail.
The dorsal and anal fins of the sunfish are flailed simultaneously when swimming, somewhat like oars.
The common sunfish (Mola mola), slender sunfish (Ranzania laevis), sharp-tailed sunfish (Masterus lanceolutus),
and southern ocean sunfish are the four species of sunfish (Mola ramsayi).
The biggest bony fish species still in existence is the sunfish.
On average, common sunfish weigh around one metric tonne.