Picasso Triggerfish: A Marine Aquarium Masterpiece

Picasso Triggerfish (Rhinecanthus aculeatus)

Picasso Triggerfish (Rhinecanthus aculeatus)

Certain fishes available in the marine aquarium trade are truly bizarre in their coloration and patterning. Ranked high among them when it comes to both exotic appearance and aquarium adaptability is Rhinecanthus aculeatus, better known as the Picasso triggerfish or the Humuhumu triggerfish.

This latter appellation (which is also applied to the closely related and similar looking R. rectangulus) is derived from the Hawaiian name for the species: Humuhumu nukunuku apua’a, which, if memory serves, translates loosely into “Man, how many Mai Tais did I pack away last night!?” I could be wrong on that.

Physical traits

Huma Huma TriggerfishR. aculeatus exhibits “typical” triggerfish morphology, with a highly laterally compressed body; high-set, independently moving eyes positioned far back on the head; a deceptively small, forward-set mouth; and a stout first dorsal spine that can be “locked” in an upright position to secure the trigger in a reef crevice when the fish is threatened. The maximum recorded length for this species is around 10 inches.

I could try to describe the color and patterning of R. aculeatus, but it wouldn’t do this fish justice. Suffice it to say, the moniker “Picasso trigger” is apropos given this species’ almost surreal black, blue, yellow, and orangish-brown striping. You really have to see a specimen in photos or, better yet, in person to appreciate its beauty.


According to Fishbase, in the wild, R. aculeatus feeds on algae, detritus, mollusks, crustaceans, worms, sea urchins, fishes, corals, tunicates, forams, and eggs. Examples of good options for captive feeding include various fresh seafoods (clams, shrimp, squid, etc.); frozen mysids, plankton, and krill; and frozen formulations for omnivores/herbivores. Multiple daily feedings are advised.


I’ve read/seen recommendations for keeping this species in tanks as small as 55 gallons. However, while a tank this size might suffice for a small specimen, it is grossly inadequate for an adult. In fact, I wouldn’t advise going any smaller than 125 gallons for this species. Also, keep in mind this trigger’s propensity to rearrange aquascaping and nibble on objects in its environment. Make sure all rockwork is well secured, and it’s wise to place heaters and other equipment down in a sump if possible.


R. aculeatus isn’t nearly as outright murderous as some balistids, which makes it one of the more community-friendly triggers. Still, it can be aggressive, some individuals more so than others. Any tankmates should be big enough to avoid being swallowed and tough enough to shrug off the trigger’s aggression if it should happen to “go rogue.”

Reef tank keeping cannot be recommended, as R. aculeatus will nip at or eat many types of invertebrates, both sessile and motile.


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About Jeff Kurtz

Jeff Kurtz is the Co-founder/Editor of Saltwater Smarts, former Senior Consulting Editor for Tropical Fish Hobbyist Magazine, and the aquarist formerly known as “The Salt Creep.” He has been an aquarium hobbyist for over 30 years and is an avid scuba diver.


  1. Paul Baldassano says

    I recently went diving in Hawaii with these guys and they are very common there. Triggers and Moorish Idols are one of the most common fish there. Their full name is Humahumanukanukaapui. But I may have spelled it wrong. It is mentioned in a famous Hawaiian song which the name eludes me now. http://i258.photobucket.com/albums/hh270/urchsearch/2013-10-17054621_zps50ad42ab.jpg

  2. Uli (sfbreeze) says

    The Picasso is an awesome pet to have, indeed a very pet like fish. He definitely needs his space and I recommend mapping out a plan if you intend to have this trigger long term.

  3. I have velvet in my marine tank i have given the fish a fresh water bath will this help

  4. Is it normal for the Huma Trigger to lay flat on the sand when they rest?

    • Hi Natasha! Yep, that is a commonly observed behavior in this species, so there’s no cause for alarm as long as it’s behaving normally, looking healthy, and eating well otherwise.

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