- Who
- Photocorynus spiniceps, Professor T W Pietsch
- What
- 6.2 millimetre(s)
- Where
- Not Applicable ()
- When
According to research published by Professor Theodore W Pietsch (USA) of the University of Washington, Washington, USA, on 25 August 2005, the smallest fish, and indeed the smallest vertebrate is a sexually mature adult male Photocorynus spiniceps, collected from a depth of 1,425 m (4,675 ft) in the Philippine Sea, which measures 6.2 mm (0.24 in) long. Interestingly, this species of anglerfish, reproduces through sexual parasitism whereby the male permanently attaches itself to the larger female (at 46 mm, 1.8 in long) by biting the female's back, belly or sides and essentially turning her into a hermaphrodite.
