Moorish Idol
Zanclus cornutus
The Doomed Fish (8 inches / 20 cm). Made famous as 'Gill' from Finding Nemo, the Moorish Idol is notoriously known in the marine hobby as the 'Impossible Fish'. Unless housed in a 500-gallon public aquarium, its survival rate past one year is virtually zero. They are notoriously impossible to feed, slowly starving to death by refusing almost all captive foods.
Wassertemperatur
24 - 28 °C
pH-Wert
8.1 - 8.4
Wassertyp
Meerwasser
Tankfüllstand
Unten und in der Mitte
Erwachsenengröße
22 cm
Mindesttankvolumen
>= 300 L
Mindestgruppe
>= 1
KH
7 - 15 dKH
Artbeschreibung
Geographical Origin and Habitat: Tropical Indo-Pacific (from East Africa to Hawaii). Inhabits coral lagoon reefs, reef slopes and deep wrecks (up to 180 meters / 600 ft), where it grazes on sponges among the rocks.
Taxonomy and Morphology: Moorish Idol (Zanclus cornutus). The only living species of its family (Zanclidae). Often confused with butterflyfish (Heniochus), but related to surgeonfish. High and compressed disc body, elongated snout and dorsal fin extended into a long and spectacular filament (Pennant).
Social Behavior: Hyperactive and difficult. Incessant and neurotic swimmer, never stands still. In nature it lives in small groups, but in the aquarium it is extremely intolerant towards conspecifics (they kill each other) and must be kept alone.
Coloration and Sexual Dimorphism: The Moorish Idol (Gill from "Finding Nemo"). Black vertical bands on a bright white/yellow background, with a "nose" saddled with bright neon orange. They develop two ossified "horns" above the eyes (hence "cornutus"). No dimorphism.
Pflege, Zucht und Mitbewohner
Aquarium Setup: Exclusive for Experts (Minimum 180 cm / 72 inches / 200G). Needs a monumental tank with huge expanses of free swimming space and rocks colonized by sponges. They suffer terribly in closed spaces and get depressed easily.
Diet and Feeding: The Feeding Challenge. Spongivore (Sponge specialist). 90% of Zanclus starve in the aquarium because they refuse any substitute food. They must be fed with frozen sponge-based pastes for Angelfish (Angelfish formula), fresh open clams and Nori seaweed, several times a day.
Water Quality: Intolerant to any fluctuation or pollutant (Pristine Water). A slight ammonia or nitrite spike leads to immediate lethargy.
Compatibility and Cohabitation: Very shy at first, allows itself to be stressed by overly lively tankmates (aggressive Tangs) that would prevent it from feeding. Not Reef Safe (nips LPS corals and ornamental sponges).
Aquarium Breeding: Totally impossible. The larvae spend a very long pelagic period developing an alien morphology before settling on the reef.
Risks and Diseases: Premature death. Fish ethically not recommended to the average hobbyist. The difficulty of weaning and the propensity to get sick with ich due to travel stress make the survival rate in the aquarium after one year frighteningly low.
Geografische Herkunft und Verbreitung
Tropical Indo-Pacific (from East Africa to Hawaii). Inhabits coral lagoon reefs, reef slopes and deep wrecks (up to 180 meters / 600 ft), where it grazes on sponges among the rocks.
Ursprung
Tropische Ozeane und RiffeAfrika und Madagaskar
Fischprofil
- Temperament
- Semi-aggressive
- They possess a timid and highly delicate temperament, making them easily stressed by aggressive tankmates, poor water conditions, or inadequate diet. Despite their striking appearance and active swimming habits, they are not aggressive and will usually retreat when challenged. Acclimation to captivity is extremely difficult, and they often refuse to eat in the presence of more boisterous species. They require a serene environment, immaculate water parameters, and an expert-level aquarist dedicated to meeting their incredibly demanding care requirements.
- Diät
- Omnivore
- Their diet is notoriously difficult to satisfy in captivity, making them one of the most challenging marine species to keep long-term. In the wild, they graze heavily on sponges, tunicates, and benthic algae, which are difficult to replicate in the home aquarium. It is crucial to offer a highly varied diet of high-quality frozen foods, including mysis shrimp, specialized sponge-based angelfish diets, and finely chopped seafood. Regular feedings of spirulina and nori are also required, and soaking foods in vitamin and garlic supplements can help encourage feeding responses.
- Lebenserwartung
- 10-15 years
- Erwachsenengröße
- 22 cm
- Geschlechterverhältnis
- Solitary
- There is no reliable method to visually distinguish males from females, as they exhibit no obvious sexual dimorphism. In the home aquarium, they should strictly be kept as solitary individuals unless the tank is exceptionally massive (several hundred gallons). Attempting to keep multiple individuals in standard home aquariums almost invariably results in severe, often fatal, aggression and stress. Even in the wild, they are frequently observed singly, in pairs, or occasionally in small schools, but this social dynamic cannot be replicated in captivity.
- Fütterungsfrequenz
- Twice daily
- Due to their exceptionally high metabolic rate and small stomachs, they must be fed small amounts very frequently throughout the day. A minimum of three to five feedings daily is required to prevent them from slowly wasting away in captivity. An automatic feeder dispensing high-quality pellets can assist when the aquarist is away, but cannot replace the need for frequent offerings of frozen and fresh foods. Continuous access to live sponge growth or live rock on which to graze between meals significantly improves their chances of survival.
- Bioload
- Medium to High
- This species generates a heavy bioload, primarily due to the frequency of feedings required to maintain its high metabolism and delicate health. Their specialized diet and the sheer volume of food necessary quickly degrade water quality if the aquarium's filtration is not exceptionally powerful. An oversized protein skimmer, large refugium, and strict adherence to regular water changes are absolute necessities. Without meticulous nutrient export, the resulting poor water chemistry will swiftly compromise the immune system of this sensitive fish.
- Fluss
- Strong
- Zanclus cornutus needs brisk, oxygen-rich circulation, with the strongest return flow spread through open water rather than aimed continuously at one refuge. Exclusive for Experts (Minimum 180 cm / 72 inches / 200G). Needs a monumental tank with huge expanses of free swimming space and rocks colonized by sponges. Keep solid cover available so the fish can leave the fastest water whenever it chooses.
- Sprungrisiko
- Yes
- While not as notorious for jumping as some wrasses, they are easily startled and capable of leaping from an open aquarium. A sudden movement outside the tank, aggression from tankmates, or unexpected lighting changes can trigger a flight response resulting in a jump. Using a secure, tight-fitting mesh lid is highly recommended to protect this difficult-to-acclimate and expensive fish. A screen top also ensures that gas exchange is not impeded while providing absolute security against jumping.
- Reproduktion
- Oviparous
- They are pelagic spawners, releasing buoyant eggs and sperm directly into the water column during coordinated spawning ascents. Captive breeding has never been successfully accomplished due to the immense space required for their spawning rituals and the complex dietary needs of their microscopic larvae. The larvae possess a uniquely extended pelagic phase, drifting in ocean currents for extremely long periods before settling onto the reef. As a result, every specimen available in the aquarium trade is collected directly from the wild.
- Kompatibilität & Tankkameraden
- Reef safe
- They are generally peaceful but should only be housed with very carefully selected, docile tankmates that will not outcompete them for food. Aggressive, fast-swimming species like large tangs or aggressive angelfish can easily intimidate them, causing them to hide and refuse to eat. They are not considered reef-safe, as they are notorious for picking at and consuming large-polyp stony (LPS) corals, soft corals, and sometimes even clam mantles. The best companions are peaceful planktivores or small, non-threatening community fish in a very large, mature system.
- Tankfüllstand
- Middle/Bottom
- They are open-water swimmers that utilize the entire vertical space of the aquarium, from grazing near the substrate to swimming actively near the surface. They require massive amounts of unobstructed horizontal swimming space to accommodate their cruising behavior. At the same time, they need complex rockwork with large caves and overhangs to retreat into when they feel threatened or stressed. Providing a balance of wide-open swimming lanes and intricate hiding spots is critical to their long-term psychological well-being.
Wissenschaftliche Modelle & Parameter
FishBase
Zugang zu den offiziellen wissenschaftlichen Daten der Art
FishBase v25.04Daten synchronisiert am: 15.06.2026
- Trophäenniveau
- 2,5 ± 0 se
- Phylogenetische Einzigartigkeit (PD50)
- 1.5
- Bayessche Längen-Gewichts-Beziehung
- a = 0.01738, b = 3.06
- AnfälligkeitGeringe Anfälligkeit (13 / 100)
Verwandte Arten
Empfehlungen gruppiert nach nahen Verwandten, Auswahl von Begleitern und ähnlicher Betreuung.
