Most Triggerfishes are brightly colored and marked with patterns of lines and spots. They are easily recognized by their deep flat bodies, small pectoral fins, small eyes placed high upon the head, and rough rhomboid-shaped scales that form a tough covering on their body. Near the area in front of the tail, they have some prickly, spike-like rows of spines that discourage predators. Also because of the rough, spike-like texture of these fish's bodies, they can easily get snagged in an aquarium net, causing some scale damage.
These fish have an angular-shaped head that extends into a long snout-like nose that possesses very strong jaws and a small mouth full of eight heavy-duty teeth.
Triggerfishes range in average size from about three to twelve inches, with some larger species reaching up to 14 or 16 inches, and a few growing to about two feet.
Triggerfishes are easily recognized and named for, you got it, their flexible trigger spines. This fish has a top dorsal spike that can be put into an up or down position at will. At the bottom of the body, there is another smaller, permanently extended type trigger that can be flexed as well. When one of these fish feels threatened, is ready for sleep at night, or wants to secure itself against strong surge-zone wave action, it will go into a hole and stick up its top trigger, flex the bottom one, and then lock them both into place. This lodges the triggerfish firmly in its hiding hole.
The force of the two triggers used in conjunction with one other firmly wedges the fish into place. Once a triggerfish has "triggered in," it is next to impossible to remove it from its hiding place.
If at some point you see a Triggerfish laying on the bottom of the tank or propped up against a tank wall, don't worry, it is how these fish sleep when there is no shelter available to take cover in.
Triggerfishes are capable of making noise much like that of a pig grunting when disturbed or agitated.
It is important when identifying these fish that you refer to them by their Latin or scientific names. Because triggerfishes are collectively referred to as Humu-Humu's worldwide, and often other common names are applied to more than one species, this does not identify which individual triggerfish species you may have or are considering buying.
- Phylum: Chordata
- Subphylum: Vertebrata
- Class: Actinopterygii = Osteichthyes (Ray-Finned or Bony Fishes)
- Order: Tetraodontiformes (Puffers and Filefishes)
- Family: Balistidae (Triggerfishes)
- Genera: Balistes, Melichthys, Odonus, Rhinecanthus, Sufflamen, and others
Triggers are extremely territorial and seem to be on the move most of the time. In general, they do get along with most other fish. They need plenty of room to move around, as well as establish a territory of their own with as little infringement from other tank mates as possible. With a tendency to be aggressive towards other triggerfishes, especially those of the same species and sex, putting them together is usually not a good idea.
Their nature can be unpredictable. Sometimes they can harass and pick on other fishes, and other times they may get along just fine. When keeping other fish with a trigger, the closer the other fishes are the same size as the trigger, the less chance harassment will occur.
It is best to place triggers in an aggressive fish-only tank community along with other larger non-related species such as groupers, lionfishes, snappers, eels, hawkfishes, tangs, and surgeonfishes.
Because these fish eat a wide variety of crustaceans and invertebrates, they are not considered suitable for live rock or reef aquariums that may have these types of marine life present.
Triggerfish Habitat and Care
Triggerfish are bottom dwellers and usually live in the shallower, inshore areas of coral reefs. They are very active fish and need plenty of room to move around. They should only be kept in larger aquariums, of course, unless you have a smaller species that grows to only about two or three inches. Be sure to learn about any particular type of trigger you want to purchase. Remember, some species grow to a very large size of up to 14 or 16 inches. It is best to provide these fish with plenty of rocks, stones, or coral formations to hide in. The more objects for them to hide around, behind, or under, the better.
Diet and Feeding
Triggerfishes are one of the easiest of all marine fishes to care for. Most all species adapt quickly to aquarium life, are very hardy, and will eat just about anything you offer them as food, including fingers.
Triggerfish are carnivores that spend their days nibbling on a wide variety of echinoderms and crustaceans like crabs, shrimps, sea urchins, worms, and other invertebrates. They are not coral eaters, but they may have a tendency to pick at clams and other animals that may be attached to corals or live rock.
When looking for food in the sand, some triggers will tip up on their nose and "blow" the sand to uncover a potential meal. It is interesting to watch them eat a sea urchin. They will pick off all the spines, turn the urchin over to expose the more vulnerable area of the urchin, and with their front two bonded teeth and strong jaws, they break it open. Triggers do not attack other fish for the purpose of eating them, but they are opportunistic and will feed on the flesh of dead fish.
Triggers are messy eaters, which can contribute to high aquarium maintenance requirements, as well as result in water quality issues, particularly in small water volume aquariums. By setting up a good regular tank cleaning routine and removing larger excess pieces of food that are not eaten in a reasonable amount of time, these problems are less likely to occur.
Triggerfishes can be fed frozen vitamin-enriched preparations suitable for carnivores, as well as herbivore rations with marine algae for a balanced diet. Fresh meaty foods such as chopped shrimp, squid, clams, and fish can be offered, and soaked in a liquid vitamin (such as Selcon) to supplement their dietary requirements.
Triggerfish. Seattle Aquarium.
Rhinecanthus aculeatus. University of Michigan Museum of Zoology.