Keeping the Jewels of the Reef: The Anthias of the Genus Pseudanthias

Keeping the Jewels of the Reef: The Anthias of the Genus Pseudanthias

The Anthias of the Genus Pseudanthias

There is nothing like the sight of a shoal of anthias shrouding the top of a coral pinnacle or a reef face promontory! I will never forget the first dive I did on such a site. When I returned home to land-locked Nebraska, I was determined to recreate this reef scene in my living room. At that time (1986), very few anthias species were encountered in fish stores. The most ubiquitous species in the aquarium trade was the Lyretail Anthias (Pseudanthias squamipinnis). I acquired one beautiful male and three females and introduced them to my 55 gallon aquarium. Unfortunately, these fish which seemed so gregarious in nature, were not so social in the confines of their new home. Before long, all I had left was one very boisterous male!

Many species of anthias are now available to the home aquarist - just check out the Diver's Den® and you will see what I mean! Their current abundance is a function of their popularity with reef aquarists. Because they're not a threat to any ornamental invertebrates they're a great addition to the reef tank. But there are a number of husbandry requirements that you should consider before you purchase an anthias for your reef or fish-only aquarium. In this article, we will examine some of the aquarium needs of the members of the anthias genus Pseudanthias.

What is an Anthias?

Although it may be hard to believe, the anthias are members of the grouper family (Serranidae). This relatively large, diverse family contains some of the largest of all the bony fishes, as well as some true Lilliputians. The anthias belong to the subfamily Anthiinae. Most of the members of this subgroup are small, colorful reef-dwellers that form groups or shoals over the reef where they capture minute food items carried by ocean currents. The subfamily includes 17 genera and approximately 170 species.

The most common group in the subfamily is the genus Pseudanthias (with about 60 species). While most ichthyologists/aquarists refer to members of this genus as anthias or fairy basslets, the genus name actually translates as "false" anthias (anthias means fish, so actually it is "false fish"). So why do we call them anthias if they are actually "false" anthias? The first member of the subfamily Anthiinae to be described was a resident of the northeast Atlantic and Mediterranean. This species, known as the common anthias (Anthias anthias), was described in 1758 by the "Father of Taxonomy" Carl Linnaeus. In subsequent years, more fish were described in this subfamily and many were placed in the genus Anthias. It was not until 1981 that ichthyologists decided that many of the species placed in the genus Anthias should be moved to a genus originally described in the 1850's by Dutch ichthyologist Pieter Bleeker. This was the genus Pseudanthias. By this time, the common name anthias was being used by researchers/writers for many members of the subfamily Anthiinae, including members of the genus Pseudanthias.

Life of a Pseudanthias spp.

Although a cloud of anthias hanging above a luxuriant coral reef may give the impression of serenity, life in an anthias shoal is really rather tumultuous. Unlike a school of neon tetras, where every individual is equal in social status (this is known as an egalitarian school), members of an anthias group are competing for a position in the group's pecking order (this is known as a shoal). Let's look at a typical Lyretail Anthias (Pseudanthias squamipinnis) assemblage. This anthias forms shoals of varying sizes, from small, isolated groups that are scattered sporadically over the reef, to huge groups numbering in excess of 2,000 individuals, that cover immense sections of vertical reef face. These groups are comprised mainly of females and non-territorial males (these males hang toward the bottom of the group).

Within the anthias shoal, territorial males perform acrobatic U-swim displays and vigorously defend an area of the reef and an associated harem of females. Lyretail Anthias shoals from the Red Sea typically have one territorial male to every eight females. The size of the male's territory is a function of the female density, and can range from about 5 to 32 square feet in area (for comparison, a standard 75 gallon tank has a surface area of 6 square feet). Within the group of females, a dominance hierarchy exists, with larger individuals dominating smaller conspecifics. If the territorial male should die, the dominant female in the harem changes sex (they are protogynous hermaphrodites) in as little as two weeks and will become the new territory holder. To maintain dominance, males and larger females display at, charge, chase and sometimes nip at their neighbors.

Anthias Shoals in the Aquarium

Many aquarists make the potentially dangerous assumption that fish that live in groups in the wild will do better if kept in similar social units in the aquarium. But this is not always the case. Many hobbyists who have tried to replicate a Lyretail Anthias shoal in the home aquarium can attest to this fact.

The problem with maintaining a group of anthias in the confines of a home aquarium is related to the aggressive dominance relationship described in Part 1. A male attempts to constrain female sex change by asserting his dominance, while females too are maintaining a pecking order among themselves. The subordinate females are being harassed by both male and female tankmates, have little room to avoid these attacks, and consequently end up hiding, not feeding, and subsequently dying. In several captive anthias colonies, I have observed that females die, or get sick, in order of their rank within the dominance hierarchy; the lowest on the ladder goes first followed by the next one up and so on. Another deleterious phenomenon that often occurs in the captive anthias colony is that the male will start losing weight because of the large number of calories expended chasing conspecifics.

Now those of you that peruse the aquarium literature, or have had the good fortune to visit some public or private aquariums in Europe, have probably seen beautiful aquariums that were home to swarms of anthias! How do they do it? There are several keys to success when it comes to keeping a group of anthias. They are: species selection, shoal composition, the size of the tank, the size of the anthias group, and feeding.

The anthias species vary in their aggressiveness. Those species that are less pugnacious are easier to keep in shoals. The Peach Anthias (Pseudanthias dispar), Flame Anthias (P. ignitus), Lori's Anthias (P. lori) and the Yellow Stripe Anthias (P. tuka) are some of the less belligerent members of the genus. Unfortunately, some of these species are also the least durable of the Pseudanthias spp. Some of the more aggressive species (which are also some of the hardiest) include the Redcheek or Green Anthias (Pseudanthias huchtii), Red-belted Anthias (P. rubrizonatus), and the Lyretail Anthias. Many of the Pseudanthias fall somewhere in between these two groups on the aggression continuum. These include the Bartlett's Anthias (Pseudanthias bartlettorum), Cooper's Anthias (P. cooperi), Hutomo's Anthias (Pseudanthias hutomoi), the Stocky Anthias (P. hypselosoma), the Luzon Anthias (P. luzonensis), and the Squarespot Anthias (P. pleurotaenia). Many of these fishes are also moderately hardy aquarium inhabitants.

If you are going to attempt to keep an anthias shoal, your chances of success will increase if the composition of the group consists principally of juvenile and female individuals. You should add only one male to the aquarium, unless the tank is large enough to accommodate more. Even then, the ratio should be highly skewed toward juveniles and/or females (a good rule of thumb would be one male to every four to six females/juveniles). Fortunately, the majority of anthias species are sexual dichromatic (that is, males and females differ in color).

The size of the aquarium can also greatly impact your success in keeping anthias shoals. The general rule is that the larger the tank, the greater your chances of success in keeping a group of anthias. In a large tank, more submissive members of a shoal may be able to avoid more dominant conspecifics. In a smaller tank, it will be hard for weaker fish to avoid bullies. If you ever see photos of the European tanks, those tanks that are loaded with anthias are usually huge (in some cases, thousands of gallons).

Another trick that can increase your chances of success in keeping an anthias shoal is regularly utilized by freshwater aquarists that keep African cichlids. With this technique, you attempt to crowd your aquarium with females/juveniles (at least six to eight individuals in the shoal). By placing that many fish in the tank, you may be able to spread aggressive interactions out so that rather than one or two subordinate fish being the recipients of all the abuse, aggression is distributed around the captive population. If you decide to try this procedure it is important to introduce all the shoal members at the same time. This technique does have some drawbacks. For example, loading your tank with anthias will limit the number of other fish species you can have. It might also put an excessive load on your biological filter and increase the chances of a disease/parasite epidemic. Occasionally, if there is a great disparity in the sex ratio a dominant female may change sex.

Feeding can also reduce the likelihood of aggressive interactions between shoal members. If food is limited, fish tend to be more antagonistic toward conspecifics. While this is especially true for territorial reef fishes, a scarcity of nutrients can also lead to more quarreling in gregarious species like anthias and chromis. Feed your anthias at least three times a day (it is even better if you can feed them less, more often).

I should point out, that some anthias will do fine if kept on their own. In fact, the more aggressive species will cause fewer headaches if only a single individual is housed per tank (this is especially true if your tank is smaller, say 55 gallons or less). One drawback in keeping some male anthias (e.g., Lyretail Anthias), in an aquarium without conspecifics is that their color may change and become more like that of the female.

Feeding

As mentioned earlier, anthias can make an attractive piscine addition to the reef aquarium. They are especially sought after by coral-keepers because they do not harm ornamental invertebrates. All the Pseudanthias species are zooplankton-feeders. They eat small organisms that float around in the water column, including copepods, crustacean larvae, and fish eggs. They are very active, flitting about the water column, picking off zooplanktors.

One real problem with keeping these fishes in the reef aquarium is to ensure that they get enough to eat. Many reef aquarists are reluctant to frequently add fish food to the tank. The average reef-keeper may only feed their fish once a day, or in some cases, less often than that. The premise is, if you add lots of food, pollutant levels (e.g., dissolved organic materials) are more likely to rise, which could lead to poor water quality and associated algal blooms. Since zooplankton is usually in short supply (at least the amount required to nourish one or more zooplankton-feeding fishes) anthias often suffer from malnutrition in the reef aquarium. Today, more reef aquarists are employing effective foam fractionators (protein skimmers) to help reduce the build-up of certain pollutants. Also, coral caretakers are also beginning to realize that many of these invertebrates "appreciate" the addition of these foods as they can be an important source of nutrients for corals as well as fish. If you are reluctant to frequently feed fish in your reef tank, stay away from anthias!

So how often do you need to feed anthias? I would suggest that most species need to be fed at least 3 times a day. If you can, it is best to feed them small amounts, as frequently as you can. Some of the healthiest anthias communities I have seen were fed an almost constant "drip" of live brine shrimp during the daylight hours. One way to facilitate anthias feeding is incorporate a refugium to your aquarium system. A refugium is a separate tank that is free of predators where the aquarist can culture a variety of plankton and other small, invertebrates. The refugium is a tank placed below or alongside the aquarium. There are also a number of pre-made models available that can be hung inside or on the outside of the aquarium. In the former type of refugium the water, and associated planktors, are typically pumped into the main aquarium. The problem with this system is that some of the planktors may be killed when they are pulled through the pump. In the case of the "hanging" refugia, water is slowly pumped (e.g., 10 to 15 gallons per hour) from the display tank into the refugia and water, along with some of the small animals that it contains, pour directly into the tank over an overflow. This prevents the zooplanktors from being disabled or destroyed by the pump's impeller.

Zooplankton culture, like mysid shrimp, copepods and amphipods, are available that can be added to the refugia. These small crustaceans can be fed aquarium flake food and plant material and are typically very prolific. They provide a natural and constant food source for any anthias housed in that aquarium. They also provide a more nutritional food source, that can facilitate chromatic fidelity in these fishes, which are notorious for losing their color. Another advantage to having a well-stocked refugia is that you will not have to introduce food as frequently to ensure your anthias gets enough to eat.

Frozen mysis shrimp have also made it easier to keep certain Pseudanthias spp. as these fish have a hard time resisting these tiny crustaceans. Make sure the frozen mysid you use is not a mushy mass when thawed. Rather, the shrimp should be whole and solid. Place a chunk of frozen mysids into a cup of water from the aquarium and then pour off the water and associated swill before actually adding the shrimp to your aquarium (this will reduce the amount of pollutants you are introducing to your system). One problem with mysids, is that they lack some pigments required to keep your anthias from losing their brilliant colors. Supplement a mysid diet with some of the color enhancing flake foods. Many of the anthias will accept flake foods once they have fully acclimated to captivity.

Another great anthias food that has only recently appeared in aquarium stores is Cyclop-EEZE®. This is a very nutritious food (e.g., high HUFA and protein content), it remains in suspension longer than many foods, and most anthias love it (larger Anthiines may ignore it)! Because of its tendency to stay in suspension, it gives zooplanktivores more time to pick the food particles out of the water column. When you feed them, it is best to place the food in the out flow of a water pump, so that it moves through the water column like their natural prey. I should point out, that coral's love to eat it too!

Aquarium Conditions & Tankmates

Anthias appreciate strong current and clean, well-oxygenated water. Water movement may also help discourage aggression in these fish. For example, it has been demonstrated in the Lyretail Anthias inter-individual distances decrease when currents are strong and increase when they're slack. Anthias also make great "dither" fish, especially those species that spend lots of time swimming high in the water column. Dither fish are species that spend their time in the open and by doing so they incite more nervous species to spend time in the open.

Anthias are often quite frenetic when first added to the tank. Sudden changes in their environment, like a light suddenly turning off or on or an aquarist's hand plunging into the tank can lead to some spectacular anthias aerial displays! Aggressive tankmates can also be a curse to newly acquired anthias. I have seen dottybacks, angelfishes, hawkfishes and larger damsels pester these fish to the point of death.

When selecting an individual for your tank, choose anthias that are swimming about and avoid individuals that are hiding among the coral (this is an atypical behavior unless the fish is threatened by a predator or rival). Also avoid anthias in which the posterior part of the skull is clearly demarcated from the rest of the body (i.e., the head appears to be enlarged) and the back looks sunken in. This condition indicates the fish has lost weight (including dorsal musculature) and it will be more difficult to maintain. Although larger individuals may be more spectacular, smaller specimens often ship better and acclimate more readily to the captive lifestyle.

Although anthias are not suitable for every aquarium venue, there are species within this subfamily that consistently do well in the home aquarium. I hope the tips presented here will help you in your efforts to keep one or more of these amazing fishes.

Other Aquarium Anthias

While the genus Pseudanthias is the primary focus of this series, there are a handful of other anthias genera that are available to hobbyists.

For example, the only member of the genus Nemanthias, the Threadfin Anthias (Nemanthias carberryi), shows-up in the trade on occasion. It is a resident of the Indian Ocean and while it can be successfully kept in the home aquarium, it tends to be too challenging for the neophyte anthias-keepers. There are also several species in the genus Luzonichthys (commonly known as the slender anthias) that appear in the fish trade. They tend to be fairly durable aquarium inhabitants and their husbandry requirements are similar to that of the Pseudanthias spp.. The males of the Sailfin Anthias (Rabaulichthys spp.) have a very large dorsal fin that is erected when they display toward rivals or potential mates. They do fairly well in reef aquariums if they are fed frequently and not housed with overly-bellicose tankmates.

Another popular Anthinne is the sole member of the genus Serranocirrhitus. This fish, known as the Fathead, Sunburst or Hawkfish Anthias (Serranocirrhitus latus), is a lovely species that tends to occur under ledges or in caves. Unlike some of the shoal-forming species, the Fathead Anthias tends to occur in pairs or trios. It does well in the home aquarium if the specimen obtained has not been injured during the collection process (the swim bladder is sometimes damaged during the decompression process).

TOP 10 ANTHIAS FOR THE HOME AQUARIUM

There are several deepwater anthias that may be represented in the aquarium trade. When these species are available, they command a hefty price because there is much work and danger associated with collecting fish at the depths at which they occur (i.e., typically deeper than 200 feet of water). The lovely Blotchy Deep Anthias (Holanthias borbonius) is one such member of the deepwater Anthinne guild. It has become more readily available to hobbyists of late. It is a hardy aquarium species, but be aware that while juveniles are usually quite congenial, adults will quarrel with one another. While not limited in distribution to deepwater, the Cherry Blossom Basslet (Sacura margaritacea) is limited in its range to southern Japan and Korea. This fish lives at a wide range of water temperatures (from 55 to 80 degrees Fahrenheit), but does best when housed at 78 degrees Fahrenheit or less.

Finally, there is the genus Plectranthias (commonly referred to as perchlets). The members of this unusual genus look more like hawkfishes than their anthias kin. They spend most of their time resting on their large pectoral fins. They are very small fishes that typically lurk under ledges, among coral rubble, or in reef crevices. The only species that regularly enters the marine fish trade is the Unarmed Perchlet (Plectranthias inermis). While the perchlets are truly the "black sheep" of the subfamily, they make wonderful additions to the reef aquarium (including the nano-reef).

Scott Michael

Scott W. Michael is an internationally-recognized writer, underwater photographer, and marine biology researcher specializing in reef fishes, and was the Banquet Speaker at our 2007 and 2008 Coral Conference and Frag Swap. He is a regular contributor to Aquarium Fish Magazine, Freshwater and Marine Aquarium Magazine, SeaScope, and is the author of Reef Fishes Vol 1, Vol 2, and Vol 3, Vol 4, and Vol 5., A Pocket Expert Guide Marine Fishes, A Pocket Expert Guide to Reef Aquarium Fishes, 101 Best Saltwater Fishes: How to Choose and Keep Hardy, Brilliant, Fascinating Species That Will Thrive in Your Home Aquarium, Reef Sharks & Rays of the World, and Aquarium Sharks & Rays. Having studied marine biology at the University of Nebraska, Scott has served as a scientific consultant for National Geographic Explorer, the Discovery Channel, and French educational television.