Picasso Triggerfish

Picasso Triggerfish: A Guide to Care and Compatibility

The Picasso Triggerfish, also known as Humu-Humu, is a captivating and aggressive species of saltwater fish that is popular among aquarists for its bold colors and unique patterns. This comprehensive guide will provide all the essential information about Picasso Triggerfish care, tank requirements, feeding habits, behavior, and tank mates, so you can successfully raise these fascinating fish in your aquarium.


The Picasso Triggerfish, scientifically known as Rhinecanthus aculeatus, is a remarkable saltwater fish that boasts striking colors and patterns reminiscent of the famous abstract painter Pablo Picasso. They are native to the Indo-Pacific region, from the Philippines to Hawaii, and can be found in shallow reefs and lagoons. Known for their aggressive behavior, Picasso Triggerfish are highly territorial and require specific tank conditions and care to thrive in captivity. This guide will provide you with all the necessary information to successfully care for and maintain a healthy Picasso Triggerfish in your aquarium.

Species Overview

Scientific Name

The scientific name for the Picasso Triggerfish is Rhinecanthus aculeatus. They belong to the family Balistidae and are closely related to the more common Reef Triggerfish, or Rhinecanthus rectangulus, which inhabit the same Hawaiian and Indo-Pacific waters.

Common Names

Apart from Picasso Triggerfish, these fish are also known by their Hawaiian name, Humu-Humu. They are Hawaii’s state fish and a widespread part of the island diet. Their full Hawaiian name is humu humu nuka nuka apua’a, which roughly translates to “the fish that snorts like a pig.” This name stems from the deep grunting noise they produce, an adaptation used to intimidate predators.


Picasso Triggerfish have an oval shape and a flat body, similar to many other tropical fish species. They have a fan-like dorsal fin that runs near the back of their body and a slightly elongated tailfin. Like all Triggerfish, Humu-Humu have retractable spikes they use to secure themselves in rock crevices and protect themselves from predators.

These fish have leathery skin with uniformly arranged diamond scales. They exhibit a tannish-grey body with darker shading near the tailfin, and their bellies are white. Picasso Triggerfish have blue and black stripes crossing the crown of their head, which cover their prominent orange eyes. A yellow line encircles their mouth, and a second yellow stripe runs from the corners of their mouth to just below the dorsal fins, creating a smile-like effect.


In captivity, Picasso Triggerfish can live for up to 10 years, provided their tank conditions are well-maintained, and they are monitored for aggressive behavior from other tank inhabitants.

Average Size

Adult Picasso Triggerfish reach an average size of 10 to 12 inches. Males are slightly larger than females, but the difference is negligible, making it difficult to accurately sex these fish based on size alone.

Picasso Triggerfish Care

Caring for Picasso Triggerfish involves effectively simulating their natural environment, which minimizes stress and encourages them to remain active and engaged with their surroundings. These fish are hardy and resilient, requiring only adequate space and stable water conditions to thrive. However, managing their aggressive behavior and ensuring the tank’s cleanliness can be challenging due to their messy eating habits and the ammonia produced by their waste.

Tank Size

As Picasso Triggerfish are highly territorial and defend their territory aggressively, a tank size of at least 120 gallons is essential. A larger tank is preferable, as these fish are curious swimmers and will explore every nook and cranny of their environment. If you plan to keep more than one Picasso Triggerfish, an even larger tank is required to minimize territorial disputes and promote coexistence.

Water Parameters

To ensure optimal water conditions for your Picasso Triggerfish, maintain the following parameters:

  • Water temperature: 76 to 82°F
  • pH levels: 8.1 to 8.4
  • Water hardness: 8 to 12 dKH
  • Specific gravity: 1.021 to 1.025 sg

Tank Setup

A spacious tank with ample live rock is crucial for Picasso Triggerfish, providing hiding spots and areas for exploration. Secure and stabilize larger rocks to prevent collapses or cave-ins that could injure or crush your fish. Additionally, ensure filters, tubing, and any exposed wiring is secured and out of the Picasso’s reach, as they are known to chew on these items.

It’s important to note that Picasso Triggerfish are not considered reef-safe, as they tend to dig and uproot material, dislodging and crushing coral. They will also consume any invertebrates you attempt to use as tank accents.

Common Diseases

While Picasso Triggerfish are resilient, they can be susceptible to diseases that commonly affect tropical saltwater fish, such as Marine Ich. Quarantining affected fish in a separate tank and administering appropriate treatment is recommended. In most cases, Picasso Triggerfish respond well to treatment and make a full recovery.

Feeding and Diet

Picasso Triggerfish are voracious eaters and will readily consume a variety of meaty proteins. In the wild, they hunt by blowing bubbles in the substrate to unearth crustaceans and sea urchins. Their sharp teeth, which continually grow throughout their lives, are ideal for crushing shells and capturing prey.

In an aquarium, Picasso Triggerfish will accept live or frozen food, including smaller snails, crabs, clams, mussels, whole shrimp, and other invertebrates. They will also eat pieces of raw fish. Providing a varied diet will ensure optimal nutrition and keep your fish engaged during feeding.

It’s important to consistently offer foods with hard outer shells to help wear down your Picasso Triggerfish’s teeth. Overgrown teeth can cause discomfort and create a pathway for disease or infection. Experts recommend feeding your Picasso Triggerfish two to three times per day.

Monitor your fish’s food intake and remove any leftover organic matter from the tank to prevent the buildup of harmful chemicals that can alter water conditions. While some aquarists may attempt to feed juvenile Picasso Triggerfish pellets, wild-caught adults are less likely to accept them. If you choose to offer pellet food, opt for high-protein, low-carbohydrate formulations to meet your fish’s nutritional needs.

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Behavior and Temperament

Picasso Triggerfish are active swimmers, territorial, and curious by nature. They are most active during the day, searching the tank floor and investigating rocks and other structures. These fish are highly territorial and will aggressively defend their established areas from perceived threats.

Adequate hiding spaces and sleeping spots are essential to prevent anxiety and stress in your Picasso Triggerfish. They are known to be aggressive toward other fish and will deliver powerful bites when provoked or threatened. Carefully monitor the dynamics in your tank and exercise caution when introducing new fish to the aquarium.

Tank Mates

Selecting appropriate tank mates for your Picasso Triggerfish is crucial due to their aggressive behavior and territorial nature. Ideally, tank mates should be similarly sized and aggressive, ensuring all fish can stand their ground if necessary. Avoid housing Picasso Triggerfish with passive fish or those small enough to fit in the Triggerfish’s mouth, as they may become prey.

If you plan to keep more than one Picasso Triggerfish, it’s best to introduce two juveniles to the tank simultaneously. Familiarity may promote coexistence as the fish mature. However, housing multiple Picasso Triggerfish together is still considered risky due to their strong territorial instincts and solitary nature.

Suitable tank mates for Picasso Triggerfish include:

  • Domino Damselfish
  • Dog-faced Pufferfish
  • Foxface Rabbitfish
  • Hippo Tangs
  • Large Marine Angelfish (such as Emperor Angelfish)
  • Lionfish
  • Marine Bettas
  • Powder Blue Tangs
  • Ribbon Eels
  • Similar-sized Surgeonfish
  • Snowflake Eels
  • Wrasses


Breeding Picasso Triggerfish in a home aquarium is virtually impossible due to the specific conditions required for successful mating. In the wild, a single male Picasso Triggerfish’s territory overlaps with those of several females, forming a harem during the breeding season. The female will dig a nest-like structure in the sand, where she will lay her fertilized eggs and guard them aggressively until they hatch.

Due to the difficulty of housing multiple Picasso Triggerfish together and recreating the necessary nesting conditions, breeding these fish in captivity is not recommended for home aquarists.


Despite their aggressive nature and specific care requirements, Picasso Triggerfish can make a fascinating and colorful addition to a saltwater aquarium. By providing ample space, stable water conditions, and a suitable diet, you can successfully care for these captivating fish and enjoy their unique behaviors and striking appearance. With careful planning and attention to detail, your Picasso Triggerfish will thrive in your aquarium, providing years of enjoyment and intrigue.

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