The Foxface Rabbitfish (Siganus vulpinus) is a popular pet for saltwater aquarium owners. It is commonly referred to as the Foxface Rabbitfish or Foxface Lo and it is very closely related to the Bicolored Foxface. In nature, it is found in the western Pacific, mostly around coral reefs. They will sometimes live in schools, but many live solitary lives. Like many fish, this species is diurnal, so it is active during the day and hides in rocks to sleep at night.
This fish is colored a bright yellow over most of its body, with black and white markings on the front part of its body. At night or when stressed, it will change to a mottled brown color for better camouflage since it is more vulnerable at this time. The mottled brown coloration helps it to hide amongst similarly colored rocks and sand. Mine always had a slightly mottled brown appearance and I suspected that it had been poorly treated at the pet shop, resulting in some sort of post-traumatic stress or perhaps some genetic predisposition. Others that I have seen in photos and pet stores always have the bright yellow coloration.
This species is equipped with venomous spines on its dorsal, pectoral, and anal fins that allow it to stab predators when attacked. Under normal conditions, the spines are not easily visible since the fins are folded, but when threatened it will extend these fins, displaying a scary array of sharp spines. This makes the rabbitfish dangerous to humans and contact with these spines can be quite painful and even lead to a hospital visit. Therefore, if you have one of these in your aquarium you must wear thick rubber gloves for safety purposes. However, take note that the foxface is NOT aggressive and will generally hide when you stick your hand in the aquarium. I was able to hand feed mine by dangling seaweed sheets in the water and it would grab them out of my hand, but I never dared to stick my hands in the water without gloves.
Despite the threat posed by the spines, the foxface is very popular as a voracious herbivore. Its elongated snout is well equipped for reaching crevices in rocks to tear out macroalgae. I bought mine mainly because of a feather caulerpa problem. Every rock in the tank was covered with large swaths of this dreaded algae, but after introducing the foxface it was all gone within a few days! It kept the rocks clean after that and I never saw the feather caulerpa again. It is easy to feed this species since it will chow down on seaweed sheets and herbivore pellets and flakes.
In summary, this pet is great for saltwater aquarium owners and excels at mowing down algae problems. Its spines and quick speed allow it to hold its own against some carnivores, but it will not harass other docile tankmates, even if it is the biggest fish in the tank. However, be aware that it will grow to about nine inches, so be prepared to house it with a 55 gallon or larger tank. This fairly large fish needs room to swim and will not do well in a smaller tank.