What is the fastest fish?

The title of "fastest fish" is generally given to the sailfish, specifically the Atlantic sailfish ( Istiophorus albicans). While exact speeds are difficult to definitively measure in the wild, they're estimated to reach bursts of speed up to 70 mph (110 km/h). This is a short burst of speed, used primarily for hunting. Their average cruising speed is considerably slower.

Here's what we know about their speed and the challenges in measuring it:

• Short bursts of speed: The high speeds are achieved in short, powerful bursts, not sustained swimming. They use their sail-like dorsal fin (which can be folded down) and streamlined body to achieve these bursts.

• Measurement difficulties: Accurately measuring the speed of a fish in its natural environment is incredibly challenging. Most speed estimates are derived from observations of chasing baitfish or from tagging studies that don't always capture the absolute peak speeds.

• Other contenders: While sailfish are generally considered the fastest, other pelagic fish, such as the black marlin and wahoo, are also incredibly fast and capable of impressive bursts of speed, although likely slightly slower than the sailfish.

In short, while the exact top speed of a sailfish remains somewhat debated, the available evidence strongly suggests it holds the title of fastest fish, capable of breathtaking short bursts of speed exceeding 70 mph.