In the dark and quiet of freshwater ponds, a fish may use a cloak of chemicals to prowl for prey.

William Resetarits at Texas Tech University in Lubbock and Christopher Binckley at Arcadia University in Glenside, Pennsylvania, set up mock ponds and recorded how several species of predatory fish affected whether aquatic beetles moved in, or frogs laid eggs. The authors placed the fish in screened chambers that concealed them visually, but not chemically, and measured colonization of the ponds by more than a dozen prey species. The prey avoided ponds that contained fish such as bluegill (Lepomis macrochirus) and the bluespotted sunfish (Enneacanthus gloriosus), but ponds containing pirate perch (Aphredoderus sayanus) — a particularly rapacious beetle muncher — were almost as popular as ponds without fish, suggesting that this fish masks its scent.

Although chemical deception has been reported for specific predator–prey pairs, this perch may be the first example of generalized chemical camouflage, the authors say.

Am. Nat. http://dx.doi.org/10.1086/670016 (2013)