The Undulate Triggerfish, Balistapus undulatus, is a deep-bodied Indo-Pacific triggerfish with a green, brown, or greyish base color crossed by diagonal orange-to-yellow lines. A large black blotch sits at the base of the tail, and the pattern remains striking across the fish's life. Wild populations occupy tropical coral reefs, from deep lagoons out to seaward reef slopes, where the locking first dorsal spine lets the fish wedge itself securely into crevices. Adults reach roughly 12 inches.

Adult housing should be a large fish-only aquarium of at least 180 gallons, giving this heavy-bodied swimmer room to patrol and to claim a territory. Build the layout from substantial rockwork arranged into caves and overhangs, and seat every piece firmly, because this trigger excavates substrate, chews on rock, and rearranges anything left loose. Strong biological filtration is important as well, since the species is a messy feeder that produces considerable waste.

On the reef, Balistapus undulatus takes an unusually broad range of prey, including algae, live coral, sea urchins, crustaceans, molluscs, tunicates, sponges, hydrozoans, and fishes. In the aquarium it is maintained as a carnivore, and a rotation of meaty marine foods reproduces the nutritional variety of that wild diet.

Offer squid, krill, chopped fish, shrimp, and clam, varying the selection rather than settling into a single item. Hard-shelled foods such as whole clams or shell-on shrimp should appear regularly, as the chewing effort helps wear down teeth that grow continuously throughout the fish's life. Feeding recommendations range from one or two meals per day up to three, with smaller portions spread across the day suiting most specimens.

Squid Krill Chopped Fish Shrimp Shell-On Shrimp Clam
Adults are territorial on the reef, and in captivity this species has a reputation as one of the most aggressive triggerfishes available. It is best kept alone in a species-focused fish-only system, since it may harass or attack smaller fish, fish larger than itself, other triggerfishes, and invertebrates. Some specimens will even lunge at a keeper's hand during maintenance, so use tools and stay aware of where the fish is. Between bouts of activity it retreats to rocky caves to rest, can lock itself into a crevice when startled, sometimes produces audible grunting sounds, and routinely pushes substrate and decor around.

This trigger is not reef safe under any circumstances. Live coral is part of its natural diet, and captive specimens nip or consume sessile reef life while also hunting shrimp, crabs, snails, clams, and sea urchins. Small fish are equally at risk. Tankmate selection, if attempted at all, should be limited to large, robust species in a very spacious system, and even then conflict should be anticipated and a contingency plan kept ready.

FAQ

Frequently Asked Questions

About the Undulate Triggerfish

  • Can an Undulate Triggerfish be kept in a community reef aquarium?
    No. This species is highly territorial and aggressive, is not reef safe, and may attack fish, corals, shrimp, crabs, snails, and clams. A species-focused fish-only aquarium is the appropriate setup.
  • What aquarium size and layout should be planned for an adult?
    Plan on a 180-gallon aquarium with large, securely positioned rocks forming caves and open swimming space for territory. Expect the fish to excavate substrate and rearrange anything that is not anchored.
  • What foods support both nutrition and dental health?
    Rotate meaty marine items such as shrimp, squid, krill, chopped fish, and clam. Include hard-shelled foods like whole clams or shell-on shrimp regularly to wear down the continuously growing teeth, feeding one to three times daily.