Moorish Idols: The Dream Fish for Aquarists

by: Michael Phife

Remember Gill from “Finding Nemo” and you weren’t sure what type of fish he was? Well, he is what’s called a Moorish Idol… which, in my opinion, is one of the most stunning and magnificent fish in reef life. However, keeping this type of fish is not nearly as easy as the movie made it out to be. Many people who have saltwater tanks and are even seasoned veterans in the hobby have a very difficult time keeping these guys alive.


So, why are they so hard to keep?

For whatever reason, when they are captive in a tank, they tend to not eat, even if the water parameters and the size of the tank are perfect. Many people have been stumped about what the Moorish Idol eats in its natural environment for quite some time. Within the past 10 years, scientists and aquarium hobbyists have come to the conclusion that they are indeed omnivores with a diet ranging from various algae, mysis and brine shrimp, and a large portion of their diet relying on sponges. What is also interesting is that whenever ichthyologists dissected a Moorish Idol that died in its natural reef environment, they found that it had also been eating fish waste from herbivorous creatures such as Tangs and Rabbitfish. Not only did this raise awareness to what diet these fish require, but also that they benefit from having other reef mates in the tank with them.


Some of the wider known foods that Moorish Idols eat that you can get from local fish shops include Nori seaweed, and “New Life Spectrum” granules. These seem to be an essential staple in their diet if you want to keep them, but they also need a very mature tank with lots of sponges and algae to graze on. Though, even if you meet the feeding requirements for them, they still may not do well in captivity in general. This is one of those types of fish that are better to look at than to keep.


Other facts about them
The Moorish Idol lives in lagoons and reef beds around the Indo-Pacific region. A lot are found around Hawaii and even have the nickname “Kihikihi”, which means zigzags. For the longest time, people thought that the Moorish Idol was a relative to Butterflyfish, most likely due to how the Longfin Bannerfish (a type of Butterflyfish) closely resembles them.


However, the Moorish Idol is in a family of its own called the Zanclidae. The only other fish in this family has been extinct for about 34 million years, so seeing a Moorish Idol today is kind of like seeing a living fossil… much like a Tuatara in the reptile kingdom. These fish are also monogamous, meaning they will take a mate and stay with them for life. With all of this said, this is one type of fish that is suited more appropriately for an educational aquarium or to be left in the wild, than it is to force them into a tank at home.