Moorish Idol EXPERT (Zanclus Cornutus)

Also Known As: "Gill" from Finding Nemo

Compatibility and Behavior The Moorish Idol is one of the most iconic reef fish in the world. The body is narrow and often more tall than it is long, with bold black, white, and yellow bands wrapping around it, an elongated snout, and a long, trailing dorsal banner that streams elegantly behind the fish as it swims. While streamers aren't guaranteed, larger Moorish Idols tend to have a greater chance of having trailing streamers. The delicate, fluttering fins and gliding swimming style give it a presence in the water column that is truly unmatched in the reefing world. Personality-wise the Moorish Idol is generally peaceful toward most other fish, though it can be somewhat assertive with similarly shaped butterflyfish or bannerfish (particularly the similar-looking Heniochus Butterfly) especially in smaller aquariums. It's typically described as reef safe with caution. Many individuals leave corals alone, but some will pick at sponges, polyps, and other sessile invertebrates, particularly when not well fed. Because of the specialized diet and overall sensitivity to water parameters, this is really a species for very experienced aquarists who can offer a calm, stable community with compatible tankmates and the patience to feed it properly.

Aquarium Requirements A Moorish Idol needs a large, mature, and very stable marine aquarium with ample open swimming space and extensive live rock for grazing. A long tank footprint is ideal here, since this fish wants to cruise continuously while picking over rock faces for natural foods like sponges, tunicates, and algae. Pristine water quality, strong biological filtration, and excellent oxygenation are all essential, as this species is notoriously sensitive to swings in conditions. Because they can also be somewhat finicky eaters, they do best in low-stress environments where they're not outcompeted at feeding time by faster, pushier species. Offer a varied diet of sponge-based frozen foods (angel formulas work well), quality marine omnivore preparations, nori, and finely chopped seafood (they love chopped squid) to encourage consistent feeding and support long-term health. Even with excellent care, this is still considered one of the most challenging fish in the hobby, but otherwise easy to keep in the most mature and stable systems.

Specifications
Approximate Size: Md: 2-3", Lg: 3-4"
Diet: Omnivore with strong preference for sponges and encrusting invertebrates (sponge-based frozen foods, marine omnivore blends, nori, finely chopped seafood)
Origin: Indo-Pacific 
Care Level: Expert (very delicate, with specialized dietary and stability needs)
Reef Safe: With strong caution (may pick at sponges, corals, and other sessile invertebrates)
Temperament: Generally peaceful; can be mildly assertive with similarly shaped species
Minimum Tank Size: 125 gallons
Special Considerations: Among the most challenging species in the marine hobby; demands pristine water quality, a calm community, and a varied sponge-inclusive diet