Researches think the fish make a special material that acts as antifreeze. why do they think this?

Researchers believe that certain fish produce antifreeze proteins to survive in icy waters. These proteins lower the freezing point of bodily fluids, preventing ice crystals from forming inside their bodies. Studies have shown that these proteins can bind to ice and inhibit its growth, allowing fish like the Antarctic icefish to thrive in sub-zero environments. This adaptation is crucial for their survival in extreme conditions where other marine life cannot exist.