Say aaah! The striped mackerel (Rastrelliger kanagurta) is a fascinating fish that feeds by filtering tiny organisms from the water. This small, sleek fish can be found in tropical and subtropical waters, and is an important part of many marine ecosystems. 📸: Alex Mustard Underwater Photography

One of the most interesting things about the striped mackerel is the way it feeds. Rather than actively pursuing prey, this fish swims with its mouth open, using its gill rakers like a net as a filter.