Cichlid Room Companion

Wayne's New World

Goin' South part 04: The "true" and "blue" Acaras, Aequidens and Andinoacara

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Last updated on 28-May-2014

Wayne Leibel, 2003

Classification: Species overview, South America.

" The true Acaras of the genus Aequidens and the blue and green acaras of the recently described genus Andinoacara are treated in this installment "

Andinoacara coruleopunctatus Perhaps the greatest difficulty with acaras is keeping track of their species names. Pictured is an adult female green acara, Andinoacara coruleopunctatus. Photo by John O'Malley.

In the last installment of this series (March 1992), we discussed the "port" cichlids and their recent nomenclatural upheaval. You will recall that the "port" cichlid was originally placed in Heckel's (1840) genus Acara by Hensel in 1870. Heckel chose the name "acara" by virtue of its usage as the native Guarani name for these egg-shaped cichlids, which we in the hobby commonly refer to as acaras. However, most of us are familiar with these fish as members of the genus Aequidens.

The American ichthyologists Eigenmann and Bray erected the genus Aequidens in 1894 as a replacement for Acara when they discovered that the type specimen of the genus, Acara crassipinnis, was actually a junior synonym of the oscar, Astronotus ocellatus, a fish substantially different from most other "acaras." The name Aequidens, which translates to "equal tooth" refers to the absence of the enlarged pseudocanine teeth that are often found in members of the "cichlasomine" lineage.

All members of the genus Aequidens have small conical teeth instead, and most (but not all) have only three hard rays in their anal fins versus four or more in "cichlasomines." They also have gill arches without lobes and small gill rakers. These fish are viewed as rather primitive cichlids.

While the first two characteristics (teeth and anal fin rays) more or less cleanly separate the "acaras" from the "cichlasomines," the genus Aequidens as thus defined is a rather mixed bag of fishes. In the same monograph in which he lumped the "port" acaras together under the redefined genus Cichlasoma, Sven Kullander (1983) intimated that the genus Aequidens, broadly defined, was ripe to be split off nomenclaturally.

He suggested that Aequidens, strictly speaking, should be applied only to the larger forms, such as Aequidens tetramerus and Aequidens metae. The rest of the known species should therefore fall biologically and taxonomically into meaningful natural groupings, such as the "blue acara" group, or the "smiling acara" group or the "mouth brooding acara" group.

Kullander has, since that time, made good on his promise of restructuring the acaras. In 1986, he restricted the genus Aequidens to several large — and medium — sized species, including Aequidens tetramerus, which could rightly be called the "true acaras." We will do so in this article.

He also erected the genera Bujurquina and Laetacara to hold respectively the "mouth brooding" and "smiling" acaras. In subsequent work (Kullander 1989), he has defined the genera Krobia, Cleithracara and Guianacara to hold some of the other orphaned acaras. He has not yet dealt with all of them — in particular, the "blue acaras," which we are also going to meet in this article. For this reason, we will refer to the "blue acaras" as "Aequidens" to indicate their present in limbo status.

Author’s Update 2014: In 2009 (Musilova et al. 2009) the new genus Andinoacara (“Andes Acara”) was erected for the “blue” and “green” acaras, and the the ‘Silbersaum’ has been described as A. stalsbergi. Since then, an additional green terror, A. blombergi Wijkmark, Kullander & Barriga, 2012 has also been described in addition to the original A. rivulatus. Despite these recent changes "blue acaras" and "Aequidens" have been retained here as in the original publication.

"True" Acaras in the aquarium

Members of these two assemblages, the "true" acaras (Aequidens) and the "blue" acaras ("Aequidens"), have long histories as aquarium residents. According to Sterba (1969), the saddle acara, Aequidens tetramerus, and the blue acara, "Aequidens" pulcher (or latifrons) were available in the German hobby before 1910. Accounts of these same fish appeared in the American literature a short time later. The blue acara, in particular, was something of a staple in the early hobby, along with the "port" acara (Cichlasoma portalegrense), for reasons of coloration as well as easy and exemplary parenting.

The "true acaras" of the genus Aequidens, as defined by Kullander (1986), comprise some dozen species of mid-sized to large cichlids found throughout South America. The species roster includes the flagship species tetramerus, along with chimantanus, diadema, metae, pallidus, paloemeuensis, patricki, plagiozonatus, potaroensis, tubicen, uniocellatus, viridis and several as yet unnamed species (see Table 1). Note that Aequidens awani, a name that appears associated incorrectly with a number of acaras, is actually a synonym of Aequidens viridis. This fish (awani/viridis) has never been in the aquarium hobby, according to Stawikowski and Werner (1988). Aequidens tetramerus is particularly widely distributed and will, no doubt, be split into several species when Kullander revises the cichlid fauna from northwestern and southeastern South America.

Aequidens tetramerus Aequidens tetramerus. Photo by John O'Malley.

Only some of these species have entered the aquarium hobby. The "true" acara species that actually arrive usually do so as contaminants and are sold — predictably — as "port cichlids" because they share the same generalized "egg-shaped" body plan of these fish. Here's where the collector's mentality really has a field day-there is nothing so exhilarating as cherry-picking oddball acaras from wild shipments. Be sure to ask your dealer or wholesaler what country the shipment is from (Hint: South America is not a country!) as this will aid in identifying the fish.

Most juvenile acaras are brown, rather non-descript fish, so any information as to their origin will help. Some of the more colorful species have been available, of late, from European breeders. These include Aequidens metae, Aequidens diadema and Aequidens patricki. The rest of the fish are variations on the theme of "saddle acara." Personally, I've never met an acara I didn't like!

The "true acaras" are large fish, with some species reaching 25 centimeters (10 inches) or so in total length. Virtually all of them are characterized by a dark mid-lateral blotch that, when the fish are in spawning/brooding condition, darkens and is flanked by lighter vertical bands before and after, and a smaller blotch on the upper quadrant of the caudal peduncle. Most have a triangular black blotch on the gill cover just below the eye.

The body color is typically iridescent green or gold (bronze?), with scales often edged in black, not unlike the "port" cichlid. Often the "face" (pre-operculum) is decorated with a reticulum of metallic streaks or spots, the coloration, intensity and complexity of which will vary from species to species. Many aquarists find them "muted" or "understated" and will pass them by, but I have a real spot in my heart for them.

My friends call them "Leibel fish." Translation: brown and plug-ugly. (Actually, real "Leibel fish" are expensive and hide a lot. Most acaras are cheap and quite boisterous.) I recommend the excellent book by Stawikowski and Werner (1988), regrettably in German, as the best color photo resource as yet available for these fish.

Unfortunately, as befits cichlids of this size, many of the "true acaras" are highly belligerent toward each other and other fish. Their place is definitely in the "rowdy" tank with medium to large cichlasomine cichlids of similar temperament. They are usually undemanding with respect to nutrition and water chemistry.

They will eat anything. While they can be conditioned to spawn on flake and pelleted foods, it goes without saying that frozen foods, such as blood-worms, or live foods, such as dwarf red earthworms, go a long way toward increasing their color and breeding success. And when you start with the basic color of brown, you need all the help you can get! Unlike the "port" acaras, however, most of these are definitely tropical cichlids, requiring temperatures from 21 to 29 degrees Celsius (70 to 85 degrees Fahrenheit).

Most of the species whose reproductive habits are known have proven to be substrate spawners. Often they are capable of spawning at modest, sub-adult sizes, which minimizes the compatibility problem inherent in attempted pairings of large adult fish. As is usually the case with cichlids, it is best to purchase five to eight juveniles and raise them together to ensure a pair-they will pick their own mates.

Although the sexes are quite similar in appearance and size, males are typically longer in the body and females are more egg-shaped, particularly when well-conditioned. If adults are all you can find, house them in a large tank with lots of rock-work, clay flowerpots, PVC pipes and/or driftwood to provide hiding places. They can share their space with large, fast-moving dither fish like silver dollars (Metynnis sp.) or elongate hatchetfish (Triportheus sp.) and compatible target fish, usually other cichlids of similar temperament.

You may even be reduced to housing them separately and attempting a spawning using the divided tank method: a piece of plastic egg-crate fluorescent light diffuser separating the combatants but allowing the male to fertilize eggs-placed on the bottom near the divider-through the half-inch square openings. See Loiselle (1987) for a more detailed description of this method.

Often it simply takes a few weeks of heavy feeding in separate tanks to bring the female into spawning condition. It is usually the male who is always ready for fun and who will soundly thrash an unresponsive female in the confines of an aquarium. If they are housed together in the same tank across an egg crate or glass divider, a conditioned female will often begin courting her prospective consort with lateral displays and head snaps. When this happens, it is time to remove the divider and watch!

If the female is ready and they accept each other, you may be able to remove the divider permanently. But watch your fish carefully for at least an hour (better, throughout the day if possible), to see whether they will be compatible — don't pull the divider and go to work. The result of such carelessness? Sushi, often enough.

Your fish may need a referee-you. Also, target fish are a real help in cementing and maintaining that otherwise fragile pair bond. Give them some other fish to take out their aggression on — and, of course, give these fish some hiding places! Alas, they may never settle down as a pair, at which point the divided tank method is the proper prescription.

Although most of the species of "true acaras" are substrate spawners, two species Aequidens diadema and Aequidens pallidus (formerly duopunctatus) are known to be primitive mouth-brooders. They guard their clutch of eggs for 48 hours and then take the eggs in their mouth for the additional 48 hours it requires for them to hatch (Prick 1978, Stawikowski and Werner 1988). As soon as they are hatched, the youngsters of most acaras are usually quite hardy and large enough to take newly hatched brine shrimp (Artemia nauplii).

One caution. Don't start breeding "true acaras" with the idea of actually making money. With few exceptions, the young are drab brown and unsaleable to any but true fanatics like myself! Breed them for the enjoyment of seeing cichlids being cichlids. That is, parental with a vengeance.

Two "true acaras" with some commercial potential are Aequidens metae and Aequidens patricki. The former sneaks in as an occasional contaminant of Colombian shipments because it lives in the Rio Meta — a tributary of the Orinoco — in that country. Both Aequidens metae and Aequidens patricki have trickled in recently as tank-raised imports from our German counterparts.

Aequidens metae An adult male Aequidens metae that is 14 cm in length (5.5 in), not including the tail. Photo by Wayne Leibel.

The "blue" Acaras

Unlike the "true acaras," the "blue acaras" are a rather cohesive group of beautifully iridescent, blue or green fish. The group name derives from the most commonly kept of these fishes, the blue acara, "Aequidens" pulcher. The blue acara is a staple of the aquarium hobby and has been around the hobby since the early 1900s. It is a lovely beginner's cichlid. "Aequidens" pulcher hails from the northwest portion of South America, particularly the coastal regions of Venezuela, including the island of Trinidad, down to the Orinoco drainage. Because it has been commercially bred in the Orient and Florida for many years, we rarely see wild specimens of this beautiful fish.

"Aequidens" pulcher is replaced by the closely-related "Aequidens" latifrons in northern Colombia. Although many ichthyologists have considered latifrons to be merely a geographical variant of pulcher and therefore an invalid species (actually a junior synonym of pulcher), Paul Loiselle — among others — has distinguished them on the basis of dentition and scale patterns (Loiselle 1983).

All three of these "blue acaras" are medium-sized cichlids growing to about 13 centimeters (5 inches) total length. All three exhibit the mid-lateral black splotch characteristic of most acaras, and all are trimmed in the most beautifully iridescent pattern of streaks and spots along their sides and faces. The base body coloration may range from blue to turquoise and the spangles may be blue, green or golden. Often the fins are orange, even red, and likewise covered in blue or green spangles.

As is true for most fishes, geographic color variants abound! So how do you tell what you have? For starters, try to find out where your fish came from. If they are small, say 2.5 to 5 centimeters (1 to 2 inches) in length, most likely they are commercially propagated fish, probably from the Far East. There have been some wild "Aequidens" pulcher about recently, imported from Trinidad-these tend to be large adults.

"Aequidens" coeruleopunctatus have proven to be movable platform spawners like the port acaras, using waterlogged leaves as the preferred egg receptacle (see Leibel 1985). Again, offspring are no problem to raise and there is good news — these are somewhat more commercially attractive fish, although the low price of Far Eastern imports will keep you from getting rich.

Andinoacara coeruleopunctatus Andinoacara coeruleopunctatus. Photo by John O'Malley.

Although I have designated this group the "blue acaras," the remaining members might, in fact, be more correctly called the "green" acaras because their base color is a quite pleasing iridescent green rather than blue. One of these, "Aequidens" sapayensis from the Rio Sapayo of the Pacific drainage of Ecuador, has in fact been called the green acara. It looks like a smaller, less spectacular version of the green terror, "Aequidens" aff. rivulatus, perhaps crossed with a blue acara It has a white edge to the caudal just like one form of rivulatus but otherwise looks like a blue acara.

When the first green terrors were imported back in the early 1970s from Ecuador at very high prices, we called these smaller, less-expensive imposters "poor man's rivulatus." Unfortunately, they never grew into the incredibly beautiful green terrors we hoped they might be. "Aequidens" sapayensis is in every aspect of its behavior and maintenance just like "Aequidens" pulcher and just as beautiful — only green.

The green terror is another story indeed! As their common name might suggest, these are green acaras with an attitude — large green acaras with an attitude. The actual beauty of this fish defies description, so I will simply refer you to the accompanying photograph.

Although the initial identification of this fish was "Aequidens" rivulatus (Goldstein 1973), the real rivulatus hails from the Pacific coast of Ecuador, Venezuela and Colombia and east of the Andes into Peru. While superficially resembling the green terror, which is imported from eastern Ecuador (along with the "red terror," "Cichlasoma" festae), the two fish differ in the pattern of flank iridescence.

In the real "Aequidens" rivulatus, it is the centers of the scales that are iridescent, whereas in the green terror, it is the edges of the scales, leaving the centers dark. The edging on the caudal and dorsal fins of this fish are white, leading to the common name "silbersaumbuntbarsche" (silver-edged cichlid) in the German literature. The fin edging in the green terror is orange or red ("goldsaumbuntbarsche"), but I have also seen terrors edged in white. Accurate photos of the real "Aequidens" rivulatus in this country occurred in the late 1960s, as attested to by the Loiselle photo in Goldstein (1973). I have never seen the real "Aequidens" rivulatus in the fins.

So who is the Ecuadorian green terror? Eigenmann (1922) lumped the species "Aequidens" aequinoctalis (Regan) and azurifer (Fowler) with rivulatus, but in fact these may be distinct species — with the green terror being one of them.

Compounding the problem is the fact that at least one "dwarf green terror" of unknown provenance (possibly Colombia) has been introduced to the hobby. It grows to no more than 13 centimeters (5 inches), whereas the usual green terror can reach 30 centimeters (12 inches) or so in total length. These are typically white-edged on the dorsal and caudal fins. Pending more precise identification, the proper designation of these fish should be "Aequidens" sp. affin. (species affinis) rivulatus, which means, "it looks like (has affinity with) rivulatus, but we don't really know what it is." Like I said, "Aequidens" green terror.

Green terrors are wonderful fish, their belligerence notwithstanding. They do well in most tanks of rowdy cichlids, but will liquidate each other if not carefully managed. Large males make striking show fish when raised alone. Their fins will eventually grow to produce long filaments and their foreheads enlarge into that sign of impending manhood, the nuchal hump. This male characteristic is related to dominance and may come and go rather suddenly depending on the social status and physiology of the owner. Females typically remain somewhat smaller (about two thirds the size of the male), never develop the "humped" look and tend to stay round-bellied (males often hollow out as they grow and have a thinner, longer look to them).

In the early days, when large specimens (more than 20 centimeters [8 inches]) were imported, breeding them was near impossible. Not only were they "terrors" to the other fish housed with them, but males routinely liquidated intended consorts. Regrettably, I lost a lot of beautiful and expensive animals. Large specimens can be bred most effectively using the divided-tank method.

The good news is that as with the other "blue acaras," green terrors reach sexual maturity at around 10 to 15 centimeters (4 to 6 inches). Better luck is had with small pairs than with full-grown adults. They will often live together and pair up naturally at this size. So if spawning this species is on your mind, buy several, buy them young and raise them yourself.

Although wild specimens are still imported from time to time, the bulk of the green terrors sold today are commercially bred in Florida or the Far East. I was at my local wholesaler last week when a shipment of terrors came in from Singapore. These 15 centimeter (6 inch) specimens were individually bagged and arrived with the most amazing finnage I've ever seen in this fish (they are also "terrors" in the shipping box, so wild fish usually land with one spectacular fish and many eyeless and finless wonders).

There is also a dwarf variety of the fish coming out of the Far East. The males develop relatively huge nuchal humps when only 7.5 centimeters (3 inches) and exhibit spectacular coloration. If they are being juiced with hormones as I suspect, at least they remain reproductively competent, unlike some hormone-treated fish.

The tank-raised stock seems a bit calmer than that from the wild. Regardless of its reputation, this remains one of my favorite acaras, perhaps even one of my favorite cichlids.

I must mention one more member of the "blue" acara group before concluding, although you probably won't encounter it. "Aequidens" biseriatus hails from the Rios Atrato, Cauca and San Juan in Colombia and has been imported as a contaminant only rarely because these areas are not commercially collected to any great extent. I have seen the living fish only once: in the tank of Aquarium Fish Magazine columnist and photographer John O'Malley.

Although its affinity to the "blue" acara group is apparent, it also resembles a stretched-out member of the "smiling" acara group (Laetacara). It is truly an "oddball." Kullander (1983) has placed it in the "blue" acara group.

Although similar in body shape and size to the blue acara, the scales of its flanks are edged in black rather than having iridescent markings. Moreover, the mid-lateral blotch characteristic of these fishes is very high on the flank, and the normal dark horizontal stripe bends up in a convex line on its way from the gill to the caudal peduncle. I know my description is incomplete, so I direct you to a picture of this strange fish in Stawikowski and Werner (1988) or in Loiselle (1983).

Nothing has been published about its spawning behavior, although John O'Malley has had eggs several times from his two females. A fish worth looking for in shipments from Colombia.

Andinoacara pulcher Like Many acaras, these Andinoacara pulcher will use an overturned flowerpot as their breeding cave, depositing their eggs on the inner surface. Photo by Wayne Leibel.
Table 1. The true and blue Acaras
The "true" Acaras (Aequidens) The "blue" Acaras (Andinoacara)
chimantanus, Inger 1956, Venezuela diadema, (Heckel 1840), Amazonas, Orinoco aequinoctialis, (Regan 1905) (may not be a synonym of rivulatus)
diadema, (Heckel 1840), Amazonas, Orinoco azurifer, Fowler 1911 (may not be a synonym of rivulatus)
metae, Eingemann 1922, Colombia biseriatus, (Regan 1913), Colombia (restricted))
pallidus, (Heckel l840) (synonym Aequidens duopunctata and Aequidens guaporensis, both Haseman 1911), Rio Negro, Amazonas coeruleopunctatus, (Kner and Steindachner 1863) Northern Colombia, Panama into Southern Costa Rica
paloemeunsis, Kullander and Nijssen 1989, Surinam latifrons, (Steindachner 1879), Colombia
patricki, Kullander 1984, Peru pulcher, (Gill 1858), Trinidad, Venezuela
plagiozonatus, Kullander 1984, La Plata, Paraguay rivulatus, (Guenther 1859), Ecuador (Venezuela, Colombia)
potaroensis, Eigenmann 1912, Guyana sapayensis, (Regan 1903), Ecuador
tetramerus, (Heckel 1840) distributed throughout South America
tubicen, Kullander and Ferreira 1990, Rio Trombetas, Amazonas
uniocellatus, (de Castelnau 1855), Peru
viridis, (Heckel 1840) (synonym Aequidens awani Haseman 1911), Rio Guapore, Brazil


The "true" and "blue" acaras comprise a relatively large group of interesting South American cichlids. While most of the "true" acaras will never win prizes for their beauty, they are nonetheless interesting aquarium inhabitants. The "blue" acaras, on the other hand, combine ease of aquarium maintenance with pleasing iridescence. All except the green terror, that is, whose special requirements are rewarded by its exceptional beauty.

Next time, we will cover two groups of acaras of particular interest to the community tank fishkeeper-relatively peaceful, moderate-sized cichlids that can be kept with tetras and plants! The "mouth-brooding" and "smiling" acaras will be the subject of our next Goin' South.


For those of you interested in additional information about this group of cichlids, l would like to recommend Aquarium Fish Magazine columnist Dr. Paul V. Loiselle's excellent earlier series on acaras that appeared in Freshwater and Marine Aquarium (FAMA) in 1983. See the references for the exact citation.

References (13):


Leibel, Wayne. (May 21, 2014). "Goin' South part 04: The "true" and "blue" Acaras, Aequidens and Andinoacara". Cichlid Room Companion. Retrieved on June 24, 2021, from: