RSS Acclimating Anthias to aquarium life

MASA Admin

8 May 2007
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Anthias are the perfect reef fish; an active, colorful, and generally peaceful fish that typifies the beautiful and busy reef scene aquarists long to recreate. This article is for the prospective anthias-keeper looking to maximize his or her chances of success.

Pseudanthias is the most plentiful genus in the Anthiinae subfamily, nestled inside Serranidae with groupers, soapfishes, and basslets. Pseudanthias itself contains over 60 species, with enough variation in morphology, behavior, and aquarium suitability for there to be an appropriate specimen for the beginner and a genuine challenge for the advanced aquarist alike.


Pseudanthias pulcherrimus – A pair of females remaining near cover; A typical behavior for this species.

In the wild, most species of anthias feed passively. This means that they swim counter-current and maintain a relatively stationary position in the water column, letting their primary diet of pelagic zooplankton meander to them where they snatch it up with minimal effort. This feeding is punctuated by other activities, but occurs somewhat continuously throughout the day.

In effect, anthias feed like grazers- eating small quantities of food regularly and when it suits them. The anthias is genetically predisposed to this feeding behavior, and by the time aquarists receive the specimen, this instinctual behavior has been reinforced by its natural environment. The problem here is clear; the reef aquarium keeper often provides food once or twice a day, and keeps other fish that actively and aggressively pursue and consume it within minutes. The strategy of staying in one area of the tank and waiting for the food to come to you is a sure way to go hungry in a reef aquarium.

When an anthias is added directly to an established aquarium, the clock begins ticking. Either the specimen will learn to recognize prepared offerings as food and an entirely new way to feed, or it will run out of time and starve. For some this is a simple matter, but some species and individuals will never learn to eat in this environment.

Part of the challenge is that this crucial skill has to be learned in concert with other lessons; learning the territories and social structure of the established fishes, where and when to take refuge, a new day/night schedule, and dealing with the minor injuries that commonly occur during transport and introduction. Aquarists looking for the highest chances of success would be wise to remove these other variables and acclimate their Anthias in an isolated environment that allows them to focus on what’s often the most serious obstacle in keeping this genus.


Pseudanthias flavoguttatus – A small, sensitive species that’s prone to hiding due to even slight aggression.

Acclimating anthias to an aquarium life can take effort, the amount of which varies greatly from species to species. For example, Pseudanthias bartlettorum tends to be highly adaptable often somewhat comfortable with aquarium life and prepared foods by the time it reaches the aquarist, while frustrations with Pseudanthias tuka have caused many to refer to it as a fish “better left in the ocean.”

Pseudanthias in general will benefit from the respite provided by a quarantine system. The advantages of quarantine and its methods are outside of the scope of this article, but most of our goals with regard to acclimation can be achieved within the typical timelines already mandated by a proper quarantine procedure. There are copious reasons for performing quarantine concerning disease prevention, but food acclimation is an often forgotten, and sometimes necessary byproduct.


Pseudanthias bartlettorum – A hardy species that often takes to prepared foods immediately.

With a few minor adjustments, the typical quarantine environment is well suited for Pseudanthias spp. Leftover plumbing pipe or fittings tend to work best as the sole form of shelter. If acclimating more than one individual, multiple fittings are recommended as territorial aggression can arise if shelter is too limited a resource.

A good powerhead is also a necessary component for the acclimation environment. Most anthias are comfortable swimming in a steady laminar flow and creating a circular flow pattern (gyre flow) around the system helps ensure that prepared foods are presented over and over again as they make their way around the tank. The round nature of the PVC structures helps minimize food being trapped as it circulates.

Keeping the food moving in this way mimics the natural feeding style and imparts the anthias many opportunities to sample the food. Placing the powerhead near the surface or angled slightly toward it is also recommended to keep the oxygen levels high as this genus has a high metabolic rate.


Pseudanthias bicolor – A Hawaiian and Eastern Pacific endemic that is very adaptable to the reef aquarium.

The acclimation process can be accomplished in a mixed species environment, so long as there isn’t a large disparity between the aggression levels of each, as it tends to impede the progress of the more peaceful ones. There is often an inverse correlation between the group size and shyness, so working with multiple anthias at once usually gives all individuals more confidence. Most members of this genus swim in large groups in nature and find that environment very comfortable.

In captive conditions, keeping anthias in a group can bring individuals out of hiding and encourage natural behaviors. There is the rare shy exception that prefer to be alone or in small groups, but reef tanks can be busy places and learning to adapt to a busy, bustling environment has to be learned.

Generally speaking, anthias that are swimming outside of cover are comfortable in the conditions in which they find themselves. Hiding long past introduction is often a symptom that the fish finds something unpleasant or unsafe. Changing lighting, tank mates, flow, or arrangement of cover to encourage the fish to emerge from cover can help drastically improve feeding response.


Pseudanthias ventralis – A somewhat shy species that will likely prefer to be alone with conspecifics at first.

The sizes and forms of the preferred food of Pseudanthias varies wildly. Performing explicit research on each species is highly recommended to make sure that the ideal food and alternatives are at the ready. Live and frozen food is almost always the best place to begin, with pellets or flakes being taken much later in the process. Many of the larger varieties of anthias will happily take to the common frozen foods aquarists commonly feed. The more moderate or difficult species may prefer smaller provisions and even shun anything but live foods at first.

To avoid dating this article, specific branded foods won’t be recommended (R.I.P. Nutramar Ova and frozen Cyclopeeze). Frozen eggs, copepods, brine shrimp, and the smaller varieties of mysis are good places to start for anthias with a discerning palate. Hatching baby brine shrimp should be a last resort, but is occasionally necessary and usually irresistible to even the most stubborn of specimens.

At first, some individuals may not even recognize what’s being fed as food and let it float past while hungrily continuing to watch for something to eat. In the event that they do try the food, it’s not uncommon for picky eaters to sample and reject it, even for days at a time.


Pseudanthias tuka – Naturally prefers unusually small foods, but physically able to eat much larger fare with training.

Members of Pseudanthias have a complex hierarchical social structure. In the wild, they are frequently found in large numbers consisting of smaller harems; mainly groups of a small number of males and a multitude of females. All members of Pseudanthias are sequential hermaphrodites, being born female and making a protogynous transition into males under the right environmental and social circumstances. Most species exhibit strong sexual dimorphism, with males advertising their prominent status with ornamental color change and wonderfully divergent fin morphology.

As an individual in the group climbs the social ladder, its reproductive fitness increases in kind. Males will regularly spawn with every capable female in the harem. Large, dominant females will also spawn more consistently than their smaller cohorts. For this reason, there is a strong incentive to climb the ranks, leading to some fairly competitive behaviors. These behaviors are sometimes perceived by the aquarist as detrimental, but many are not a cause for concern.


A male Carberryi Anthias reaffirming its social position to one of its subordinates.

Fighting can take many forms, from biting, to body checking, to jaw locking. What’s important to note is how well received the aggression is. Jaw locking is almost always benign, as both parties have, in a sense, “agreed” to sparring. Many of these behaviors are in fact positive indicators that the specimens are healthy and have energy to spare.

A mixed species environment can complicate the acclimation process. For example, while female Lyretail Anthias are able to handle the relatively aggressive antics of a male Lyretail, a more passive species might find even slight aggression overwhelming.

Typically, aggression that isn’t well received should be a cause for concern. Non-reciprocated biting or chasing can cause an individual to become stressed. The victim is penalized for venturing out of hiding which slows or halts the acclimation process.

Temporary physical separation can solve this and give the victim some time to acclimate at its own pace. Oftentimes, this type of aggression will dissipate when both parties are introduced into the display as other fishes and more space can curtail focused aggression.


A pair of juvenile female Anthias posturing and preparing to lock jaws, a behavior that’s rarely a cause for concern.

A shoaling group of Anthias is one of the more impressive sights both on the reef crest and in the marine aquarium. Their delicate nature can make them difficult to introduce, but with the right measures they can become long term, hardy additions to your reef.

– Christopher Kriens
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