Photocorynus spiniceps, a type of anglerfish, is our smallest fish. The males, which are parasitic and attach to the much larger females, only reach a length of 6.2 millimeters long, which is less than a quarter of an inch! In contrast, the females can get up to 50 millimeters in length, which is twice as long as the eighth smallest fish on this list. If you didn’t know, anglerfish live in the deep sea and use a bio luminous bulb to trick their prey into swimming straight into their mouths. The female Photocorynus spiniceps, like other anglerfish, have teeth very similar to a Fangtooth, so their prey is unlikely to escape! The translucent males of this species, which look like wisps of crumpled tissue paper, spend most of their lives stuck onto the female and taking their nutrients from whatever she eats, so she is always eating for more than one.