Anthias: Why the Difficulty

by Mike Paletta July 03, 2024

Anthias: Why the Difficulty

(A beautiful harem of Pseudanthias bimaculatus in Andrew’s back holding tank)

The PoloReef tank is notable for its impressive variety and number of fish. Once you get past the initial amazement at the tank's size, you notice the unique groups of fish from various reefs. Among these, the Anthias stand out the most. Unlike most hobbyists who can keep only one or two species, Andrew has successfully housed at least seven varieties of Anthias in the main display tank, with more in other tanks and quarantine areas. Over time, he has developed effective quarantine and feeding methods for these fish, even for the more challenging species. In this article, he shares his successful techniques and discusses the challenges of keeping Anthias, offering potential solutions to make their care easier.


When looking at pictures of natural reefs, the first thing that usually stands out are the large shoals of various Anthias flitting about the reef face in a graceful ballet. Their magical colors glimmer in the sunlight as they move in and out of the corals. Occasionally, you might see other fish like green Chromis or a wrasse nearby, but the Anthias schools are uniquely captivating and a defining feature of the reef. In the early days of the aquarium hobby, Anthias were a staple in reef tanks for obvious reasons: they did not bother corals or most other fish, they were colorful, stayed relatively small, and were abundant. Just as different genera of corals vary in how easy they are to keep, the same is true for different genera of Anthias. However, the variability is even greater with Anthias, as there is a wide range in the ease of keeping different species within each genus. Some of the most beautiful Anthias are nearly impossible to maintain, while others thrive and even spawn in aquariums. This raises the question: how can a group of fish that look and behave so similarly have such a wide range of care requirements?

(Even a school of common anthias can put on a spectacular display)

Despite their similar appearance in body structure and color, there are significant differences not only between different genera of Anthias but also between species within a genus. Before diving into these differences, let's look at their similarities. Most Anthias are high-metabolism fish, meaning they are constantly swimming in short bursts and spend much of their time searching for food. This constant activity results in high energy expenditure. Additionally, Anthias have streamlined bodies with small stomachs, which is why they need to feed constantly, both in the wild and in aquariums. Anthias typically live in shoals rather than schools. Unlike a school, where fish of the same species swim in synchrony for protection, a shoal is a loose group of fish, often including multiple species, that move independently but stay together for protection and breeding. Within these shoals, Anthias often form harems consisting of a dominant male, several females, and one or two sub-dominant males. In some species, females can turn into males if the dominant male leaves or dies. Anthias are prevalent on most reefs in the Indo-Pacific and the Red Sea, making them common in the aquarium hobby.

The difficulty of keeping Anthias varies as widely as their colors. Although they have been kept since the early days of the aquarium hobby, recent years have seen an increase in the difficulty of maintaining even previously easy-to-keep species. This raises the question of why this is happening. Several factors contribute to this challenge, often compounding each other.

Collection and Shipping

One primary reason is poor collection and shipping techniques. Anthias, while abundant, often live in hard-to-reach areas of the reef, leading to varying collection methods. Some countries, like the Maldives, Marshall Islands, Australia, and regions around the Red Sea, are known for their good collection practices that minimize stress on the fish. However, other areas may use methods that cause significant stress, making the fish harder to keep successfully.

(The difficult to ship and acclimate male pictiliuys anthias
thriving in Andrew’s main display)

Stress during shipping also plays a significant role. To prevent water fouling, many collecting stations do not feed fish for 24-48 hours before shipping. For Anthias, which feed almost constantly, this lack of food causes significant stress. Additionally, long flights, sometimes over 20 hours, exacerbate this stress. As a result, many Anthias arrive at wholesalers refusing to eat due to prolonged food deprivation, which diminishes their eating drive. This is why a variety of foods, including live foods, are often necessary to encourage newly acquired Anthias to eat. When these fish arrive with pinched bellies, indicating they haven't eaten for a long time, they rarely recover.


Improper or inadequate acclimation is often a significant cause of short-term survival issues for Anthias. These fish are highly sensitive and require pristine, highly oxygenated water with stable parameters. Many Anthias come from regions with daylight cycles that are approximately twelve hours different from their new environment. This time shift can cause stress similar to jet lag in humans, affecting their feeding behavior. To mitigate this, when Anthias enter quarantine, they are initially kept under subdued light on a twelve-hour shift opposite to their eventual tank lighting. Over a month, the lighting schedule is gradually adjusted to match the main tank. This lighting acclimation is crucial, especially for deep-water species like Pseudanthias ventralis and Serranocirrhitus latus, which are not accustomed to the bright lights and warmer temperatures typical of most reef tanks. Ideally, these species should be housed in tanks with lower light intensity and cooler water.

(A Barlett’s anthias showing its full potential
when given adequate space and nutrition)

Another important aspect of acclimation is addressing the shyness of newly acquired Anthias, which often spend the first few days hiding in live rock and not feeding, leading to increased stress. To mitigate this, once having gone through proper quarantine in outside tanks, all quarantined Anthias, should be placed in clear holding containers within their new tank. The container should include PVC pipes of various sizes and small pieces of live rock. This setup allows the fish to acclimate to the tank’s water conditions and tankmates, facilitates better observation of their feeding habits, and helps reduce any aggression from other tank inhabitants. Using this method can significantly reduce the mortality rate of these and other fish, especially once they start eating.


Proper quarantine is essential for all fish, especially Anthias, which are particularly susceptible to Uronema infections. These infections are seemingly more common now than in the past. Uronema is a free-living ciliated protozoan that primarily attacks Chromis and Anthias, and occasionally angelfish and butterflyfish. It can infect any weakened fish and does not require a host to survive, thriving on bacteria, waste, and decaying food. Therefore, it cannot be eradicated by leaving a tank fallow. Uronema kills weakened fish by consuming their internal organs and muscles, making it a highly undesirable pathogen in display tanks due to its indefinite survival and limited treatment options. Given these risks, quarantining all newly acquired Anthias is crucial.

(An inadequately quarantined anthais that died of Uronema,
note the red markings)

Andrew's quarantine method for Anthias involves a separate quarantine system, not the display tank. Initially, all new fish receive a formalin bath at a dosage of 0.6 ml/gallon, increased to 1 ml/gallon if flukes are present, for no more than thirty minutes. A second formalin bath may be given after five days if necessary. In the quarantine system, the copper level is gradually raised from 1 ppm to 2-2.2 ppm using CopperPower, as Anthias are sensitive and cannot tolerate higher levels. During this period, small foods like baby brine shrimp, golden pearls, calanus, and fish or lobster roe should be fed. Any uneaten food should be siphoned off to prevent Uronema from feeding on it. After two days, 0.9 ml/10 gallons of formalin is added along with copper for an additional 10-14 days. During this time, food containing Metronidazole and Fenbendazole is provided to medicate the fish internally. If Uronema is internal, survival chances are slim. Dr. Alex Hall suggests that injecting Metronidazole and other antiprotozoal compounds may be more effective than using Metro and antibiotics in the water or food. Andrew is considering this approach, as treating internal Uronema has been largely unsuccessful to date. After completing the treatment, the fish are maintained with copper until they are "clean." They are then moved to a sterilized quarantine system and treated for "worms" with Prazipro and medicated food. Although this quarantine process may seem extensive, the healthy and thriving Anthias in the display tank demonstrate its effectiveness.


Poor nutrition, alongside diseases, is a leading cause of Anthias mortality. Anthias need to feed constantly while they are awake, requiring a feeding schedule of five or more times per day to thrive in a reef tank. Feeding them only once a day is insufficient and will not keep them alive. If you cannot commit to multiple daily feedings, it is best not to keep Anthias. However, automatic feeders can help maintain their feeding schedule. It is crucial to provide small amounts of food as often as possible to ensure their health and well-being.


(A rare sight at the Long Island Aquarium is a harem of Purple Queen Anthias successfully weaned onto mysis, living with a colony of garden eels)

Feeding Anthias often is crucial, but providing the right type and size of food is equally important due to their small mouths. Two particularly challenging species, Purple Queens and Evansi, have very small mouths and are picky eaters. Despite their beauty, Purple Queens are among the hardest fish to keep long-term. Andrew attempted to raise a hundred of them, constantly dripping live baby brine shrimp into their tanks, but only six survived quarantine. His success with Evansi was slightly better using the same protocol. Previously, the frozen copepod product Cyclopeeze was highly effective, as all Anthias, especially Purple Queens, fed on it voraciously. Unfortunately, when Cyclopeeze became unavailable, many Anthias, including the thriving Purple Queens, died of starvation because they could not be weaned onto other foods. Cyclopeeze's availability had significantly contributed to the success many enthusiasts had with keeping Anthias.

(The shyness of these fish can be seen here as most of the anthias
are feeding elow their more aggressive tankmates)

Anthias are true planktivores and require planktonic food, especially during quarantine and acclimation. Suitable foods include frozen, fresh, and freeze-dried copepods, mysis, baby and adult brine shrimp, and fish and crustacean roe. Gradually, you can mix in pellet food to wean them onto a more convenient diet, allowing the use of automatic feeders for continuous feeding. Initially, live foods like baby and adult brine shrimp and live rotifers may be necessary to encourage feeding due to their movement. Once they start eating, you can introduce frozen foods and eventually pellets. The goal is to provide high-energy, high-protein foods similar to their natural diet. With proper nutrition and disease management, Anthias can thrive.

Space and Tankmates

Anthias are active swimmers and need tanks with plenty of open space. They thrive in small harems, so consider this when choosing tank size. Smaller Anthias harems do well in 75-90 gallon tanks, while medium to larger Anthias require at least a 120-gallon tank. In the wild, they congregate on the reef face, so a reef face aquascape with ample open space is ideal. These fish also need highly oxygenated water with lots of movement, so providing adequate flow in the tank is essential.


In addition to providing adequate space, choosing the right tankmates is crucial for long-term success with Anthias. Despite their active nature, Anthias are not aggressive and are not aggressive feeders. Therefore, they should not be housed with aggressive feeders like large tangs, rabbitfish, or large wrasses, as these fish will outcompete them for food. Ideal tankmates include fairy and flasher wrasses, which share similar temperaments and feeding habits, as well as cardinalfish and small tilefish. Smaller Anthias are even less aggressive and should be housed with passive fish like gobies and blennies.

This Pseudanthias ventralis does best in a tank
with low lighting and docile tankmates)


An indicator of successfully keeping Anthias is their regular spawning when they are happy and well-fed. In a properly maintained harem, a dominant male will perform a spawning dance with all the females every evening just before the lights go out. This frequent behavior, once the fish are settled in, becomes a nightly spectacle to look forward to. It also serves as a positive sign of their well-being, as they will cease spawning if conditions are not right. This regular spawning is a gratifying acknowledgment that you are providing the correct care for these often-challenging fish.

Even aggressive anthias like these bimaculatus do best when housed with
less aggressive fish like this Copperband butterfly)


Anthias have been a staple in reef tanks since the hobby began, known for their diverse behavior and appearance. The difficulty of keeping them varies, but many can be quite hardy when properly quarantined, acclimated, and fed. The most challenging aspect of keeping Anthias is having the patience to care for them correctly from the start. As with any aspect of the hobby, doing things right from the beginning yields significant rewards, especially with Anthias.


Mike Paletta
Mike Paletta


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