For the scaleless and unprotected frogfish, the camouflage is an important defense against predators. Some frogfish can also inflate themselves, like pufferfish, by sucking in water in a threat display. In aquariums and in nature, frogfish have been observed, when flushed from their hiding spots and clearly visible, to be attacked by clownfish, damselfish, and wrasse, and in aquariums, to be killed.
Many frogfish can change their color. The light colors are generally yellows or yellow-browns while the darker are green, black, or dark red. They usually appear with the lighter color, but the change can last anywhere from a few days to several weeks. It is unknown what triggers the change
A Commerson’s Frogfish is photographed among tubastrea coral in Raja Ampat, West Papua province, Indonesia
Picture: DOUGLAS SEIFERT / BARCROFT MEDIA (via Pictures of the day: 3 December 2010 - Telegraph)