Among the most colorful of fish found off the coast of southern California is the Catalina or blue-banded goby (Lythrypnus dalli). As the name implies, and the photo clearly shows, these fish have an overall bright reddish orange color overlaid with neon blue stripes or bands. When diving reefs between Monterey Bay and northern Peru these fish are hard to miss. The bright colors stand out like beacons, but very tiny beacons, as these voracious predators are quite small, reaching a maximum length of only 2.5 inches (6.4 cm). It’s a good thing too that they are so small, given the impressive set of teeth they sport in their jaw. If the size of a shark, they could likely do quite a bit of damage.
Despite their small size, they are still very formidable predators. They feed primarily on planktonic organisms drifting by in the current. Their normal behavior is to sit motionless on a small outcrop watching for tiny organisms drifting by on the current. Once one is spotted, they make a mad dash out to engulf it, then dashing back to the reef for protection. Usually occurring in groups, it can be fun and mesmerizing to watch the darting action as each goby dashes out to get a snack.
Gobies are a family of fish with the common feature of having a pair of fins on their underside fused to form something of a suction cup. Most, if not all, are bottom dwellers, rather than sleek swimmers plying the currents for food. Having a much reduced, or absent swim bladder is the reason most sport more of a grab and go lifestyle. Sitting on the bottom to conserve energy until food appears, then sprinting out to get it and back to the bottom to wait again.
As with many marine fish, blue-banded gobies have been found to change sex over the course of their lifetimes. But while most sex-changing fish change one time, apparently blue-banded gobies are able to change back and forth more than once. This is a useful adaption to cope with changing sexual demographics in a population. Not enough females to produce eggs? No problem, some of the boys will switch. Pretty handy.
This photo was taken with a Canon EF100 mm f/2.8 macro lens attached to both a Canon EF12 mm and EF25 mm extension tube on a Canon EOS 5D Mk. III in an Ikelite underwater housing. Light was provided by an Ikelite DS-161 strobe in eTTL exposure mode. The exposure was set to 1/60 sec. at f/11 and ISO 100.