A Survey of Eartheaters | Tropical Fish Hobbyist Magazine

Issue: September 2011


Photo: Radek Bednarczuk

A Survey of Eartheaters

Author: Radek Bednarczuk

Picking up mouthfuls of sand to strain for food items in the substrate, eartheaters have quite the appropriate moniker. Discover the many species of geophagines for a range of aquarium sizes and styles.

Qualities of Eartheaters

The eartheaters have certain qualities that will attract almost all cichlid lovers. They come in a variety of shapes, colors, and sizes, and they demonstrate very interesting social and reproductive behaviors. These cichlids occur in all types of South American waters: still waters and swiftly flowing streams; white, black, and clear waters; and both warm and cold waters. In some of their ranges, the temperature can fall below 10°C (50°F).

Due to the great diversity of environments in which they live, almost every genus has some individual feature that makes it stand out within this group of cichlids. The majority of eartheaters are fairly large cichlids. The largest can reach 30 cm (12 inches), but the average size is 10 to 12 cm (4 to 5 inches). This group contains such genera as Acarichthys, Biotodoma, GeophagusGuianacara, Gymnogeophagus, and Satanoperca. In the past, the eartheater group also included the genus Retroculus.

The generic name Geophagus contains Greek roots for “earth” and “eat,” and the characteristic feature of eartheaters is their feeding method. The fish suck the substrate into their mouths and then, retaining any edibles, pass the rest out through the gill plates. These fish utilize various reproductive strategies depending on the species in question.

Eartheater Aquarium Needs

Water quality and substrate are primary concerns when keeping eartheaters. Regular water changes and good filtration will maintain the high water quality necessary to keep these fish thriving, and a sand substrate will enable them to display natural behaviors. These fish can produce a lot of waste, so an efficient biofilter is a must. They also need good aeration. Powerheads with sponge prefilters are excellent because at the same time they oxygenate, they remove suspended debris produced by the cichlids’ constant digging in the substrate. The setup should be adjusted to the species being kept—e.g., some eartheaters, like Biotodoma and Satanoperca, live in quiet waters and prefer mild current, while others, like Guianacara, inhabit swiftly flowing streams and love strong water flow. The majority of eartheaters (aside from Gymnogeophagus) love warm temperatures, so the aquarium should also be fitted with a heater.

The lighting should be suitable for any plants in the tank, but the eartheaters themselves generally prefer light shade. Aquarium decor should reflect the biotope in which the fish live, so it is best to use many pieces of driftwood as well as flat stones or caves. The latter will prove especially useful in the reproduction of Acarichthys and Guianacara. Driftwood not only provides hideouts for the fish and looks great in the aquarium, but it also leaches tannins, which tend to acidify the water to some extent. This is very good for the majority of the species in question.

Good choices for eartheater companions include other species belonging to the same group of fish, other bigger South American cichlids, and fish that inhabit bottom levels of the tank (i.e., the popular Corydoras or other armored catfish). Other species of fish will serve two functions: Some will spread around the excessive aggression of some eartheaters, while others, such as Satanoperca leucosticta or Biotodoma cupido, will serve as dithers and make them less timid.

Always purchase eartheaters in a group of at least a few or even more than a dozen individuals. They thrive better that way, feeling safer within a group, and their interesting social behaviors can be witnessed firsthand while increasing the chances of reproduction.

Special considerations must be made if you want to keep plants with eartheaters. In my own eartheater tanks, I use Java fern Microsorum, which I attach with transparent fishing line to the top sections of driftwood. Sometimes I include potted tough-leaved plants, usually CryptocoryneAnubias, and Echinodorus.

Feeding Eartheaters

The key to feeding eartheaters properly is knowing their natural diets, which are directly related to the environment they inhabit. The main items on their menu in the wild are tiny crustaceans, fruit fallen from trees and plants, and insects and their larvae. For this reason, eartheaters require a lot of roughage (cellulose, chitin) in their diet. These can be provided in green plants and the shells of crustaceans, and including such items in their diet can also help prevent bloat.


Geophagus species are very popular and include a multitude of color varieties. A characteristic feature of the genus is their upper head profile, which is somewhat conical in shape and features eyes placed relatively high. The body is somewhat laterally compressed, and there is a characteristic mark on the flank (the size of which depends on the species). The whole body of the fish is covered with distinct stripes. As of today, there are more than 20 scientifically described species in the genus Geophagus,and every year exporters offer new color varieties and undescribed species. These can be real finds for enthusiasts of this cichlid group.

Members of the genus Geophagus occupy a large portion of the Amazon Basin (including Guyana and the Orinoco region), where they can occur in all types of water. The species most commonly found in the trade are those that grow to about 12 cm (4¾ inches), such as Geophagus sp. “red head Tapajos” or G. abalios. The genus also contains fish measuring 25 to 30 cm (10 to 12 inches), such as G. altifrons andG. proximus. They do best at a temperature of 26 to 28°C (79° to 82°F), pH of 6.5 to 8, and general hardness in the range of 10 to 20 dGH.

These species are larvo- and ovophilic mouthbrooders. In the case of the former, one or both parents will take the newly hatched larvae into their mouths and brood them for a period of time (10 to 14 days on the average). With ovophilic species, it is the fertilized eggs that are taken into the mouth for further incubation. In both cases, the fry leave the parent’s mouth only after the yolk sac has been absorbed. Afterward, the juveniles are taken into the mouth for the night or when faced with a threat. This diligent parental care comes to an end after a few weeks, when another spawning usually occurs.

The Red-Humped Eartheaters

The red-humped eartheaters constitute a separate group within the genus Geophagus. They owe their name to the characteristic fatty hump, which is the attribute of adult, dominant males. This is not a repository of nutrients and fat but an area filled with small blood vessels that only begins developing when the males have to compete for their social position. At the time of spawning, the hump will become even bigger.

This group includes such species as G. crassilabris, G. pellegrini, and G. steindachneri.They live in water with a temperature of 26° to 30°C (79° to 86°F), soft or moderate hardness, and pH of 6 to 7. They grow to a maximum of 25 cm (10 inches). These fish should not be kept in pairs but in harems, and their behavior is similar to that of Lake Malawi mbuna. These cichlids are very hardy and also breed readily in the aquarium; they are ovophilic mouthbrooders.

The Brasiliensis Complex

Another distinct complex within the genus Geophagus is named after the best known and the first described species, G. brasiliensis. It includes such species as G. iporangensis, G. itapicuruensis, and G. obscurus. These eartheaters occur in eastern and southwestern Brazil and are found in all three types of waters: clear, white, and black. They inhabit areas of brisk current, as well as quiet waters. The substrates may be rocky, muddy, or most often sandy.

The bodies of the fish that belong to this complex are not as compressed from side to side as in other species of Geophagus. Their eyes are smaller, the mouth is positioned at the front of the head, and there are no scales on the soft dorsal. They exhibit distinct sexual dimorphism—the males grow bigger, and their upper head profile, where a fatty hump may develop, is more sloping. They also have longer fins and a metallic sheen on their flanks. They can grow to 30 cm (12 inches). Their habitats show a wide range of parameters: temperatures in the range of 16° to 30°C (61° to 86°F), hardness between 5 and 15 degrees, and a pH of 5 to 7. Interestingly, they may be found in estuaries with a conductivity as high as 3000 µS/cm.

These eartheaters are quite aggressive fish, especially at spawning time. Reproduction is similar in all the species that belong to this group. The female chooses a suitable site, usually in the shelter of tree roots, to clean and lay her eggs (up to 1000). The larvae hatch in about three to four days. The female then transfers them in batches to one of many pre-dug pits. The larvae, not yet free-swimming, are then moved from one pit to another until they are free-swimming. Parental care usually lasts about three weeks. After six to eight months of intensive feeding, the young eartheaters reach a length of about 10 cm (4 inches), which is when they attain sexual maturity.


Gymnogeophagus spp. inhabit southern Brazil, eastern Paraguay, Uruguay, and northern Argentina, including the La Plata Basin. They occur in the quieter sections of flowing water bodies and usually avoid large rivers. When they find themselves in wider waters, they seek out the quieter zones. They are most often found in lagoons or smaller streams. In their natural environment, seasonal climatic changes can be observed during the year—in the winter months, water temperature can fall much below 20°C (68°F), and in some areas even as low as 8°C (46°F)!

As of today, there are more than a dozen scientifically described species within the genus (the last to be described was G. tiraparae). The fish of this genus lack scales on the anterior part of their bodies and are noted for their beautiful colors and small size. Some species are larvophilic mouthbrooders, and others are open substrate spawners whose eggs are usually laid on a horizontal surface such as a root or stone.


Biotodoma eartheaters inhabit quiet, slow-flowing Amazonian waters. There are two scientifically described species, B. wavrini and B. cupido. They frequent shallow bays with sandy or muddy bottoms and are sporadically encountered among roots, rocks, and leaf litter. The temperature of the water bodies that both species inhabit ranges from 27 to 29°C (81° to 84°F). A characteristic black band runs vertically across each gill cover, without bypassing the eye, to reach its lower margin. Below the eyes are many opalescent lines and dots. The lips are neither thick nor fleshy, and the mouth is relatively small. A characteristic feature of the genus is a black spot, which (depending on the species) occurs below or above the lateral line, but in both it is bordered by two comma-shaped areas. As the mouths of both species are relatively minute, the food should be of small size.

The fish grow to 10 cm (4 inches) on average, and ideal water parameters are pH 5 to 6.5, temperature 28°C (82°F), and GH below 10. These eartheaters are very sensitive to high concentrations of nitrates, so substantial weekly water changes are needed. A denitrifying filter will also prove helpful in their maintenance. Water current in the aquarium should not be too brisk. These cichlids lay their eggs in the open, usually on a tree branch or a stone.


The majority of these species are typical crevice breeders, which means that in their natural environment reproduction usually occurs in narrow rocky caves. They inhabit quick-flowing waters of southern Venezuela and French Guyana, as well as the Rio Branco region. In their natural environment they establish colonies, but they breed in pairs. A characteristic feature of their appearance is a black suborbital stripe, which extends to the lower edge of the operculum, forming a black angle on the cheek of the fish. These eartheaters have a high upper head profile, but they lack the fatty hump. These cichlids have a lot in common with the genus Acarichthys. The scientifically described species are G. geayi, G. oelemariensis, G. owroewefi, G. sphenozonaG. stergiosi, and G. cuyunii.


Popular species of the genus Satanoperca are S. jurupari, S. leucosticta, S. daemon, and, much less frequently available, S. pappaterra, S. lilith, and S. acuticeps. Depending on species, the fish range from quite small to 30 cm (12 inches). Common features, among others, are scaleless dorsal and anal fins and the presence of a round spot on the base of the caudal fin.

They inhabit quiet and slow-flowing waters in the Orinoco region and the upper Rio Paraguay, as well as other rivers such as the Rio Negro and Rio Branco. They can usually be found close to the banks, where the bottom is predominantly mud, clay, or fine sand and covered with decaying leaves of terrestrial plants and submerged portions of trees, bushes, and grasses. On the other hand, true aquatic plants are rare in those regions.

The fish spend the day in deeper water to avoid the predatory birds congregating in the branches of the trees. At night they emerge into the shallows near the banks to avoid encounters with predatory catfish that are active at dusk and at night. The Satanoperca share their habitat with the predatory piranha, so the majority of wild-caught eartheaters will have major fin damage. These cichlids live in groups. Their appearance is somewhat perch-like. They have an elongated snout, large eyes, and an arrangement of the mouth that creates the impression they are constantly smiling. The scientific names of the genus and several of the species reflect the association of these fish with demons in the local people’s culture.

Some species, such as S. jurupari and S. leucosticta,are rather timid cichlids and do best with dither fish. The water for both of these species has a pH of 6.5, a general hardness of up to 10 dGH, and a temperature around 28° to 29°C (82° to 84°F). S. daemon, on the other hand, is more difficult to keep, requiring very soft and acidic water. It often succumbs to hole in the head (HITH) and bloat, which is why it is only recommended for more experienced aquarists. These eartheaters are ovo- and larvophilic mouthbrooders.


Acarichthys contains only one described species, A. heckelii. About 25 cm (10 inches) in length, this fish is native to the Rios Negro, Branco, and Rupunui, with water that has a pH of about 6, hardness below 10 degrees, and temperature of 20° to 28°C (68° to 82°F). Unlike other eartheaters, A. heckelii has a narrow body and strongly elongated dorsum. A characteristic facet of their appearance is a black spot on the flank and a stripe of the same color that runs the whole length of the gill cover. Their appeal is further enhanced by the soft rays of the dorsal, which form long filaments that are maroon red in color. Mature specimens have many opalescent bluish dots immediately below the eye. The anal and dorsal fins are covered in numerous colorful spots, and the body of the fish is olive in color. Many varieties, differing a little in coloration, can be found in the trade. One thing, however, is beyond question: These eartheaters are one of the most impressive-looking South American cichlids.

Although the fish can attain respectable size, they have small mouths with thin lips. Because of their size and aggression, they should be kept in very large tanks, with the absolute minimum for five to six adult specimens being 160-cm (5 feet) long, 60-cm (2 feet) high, and no less than 70 cm (2½ feet) in width. They can be kept with other cichlids of similar size and temperament, such as Geophagus or Heros. In nature these eartheaters breed in tunnels a few dozen centimeters (a couple of feet) in length, which they dig in the clay substrate. These are usually located close to some vegetation. Unfortunately, these eartheaters are quite difficult to breed in the artificial environment of the aquarium, and they reach sexual maturity quite late—the female at two years of age, the male at three.

Those lucky enough to obtain a mated pair can offer them spawning sites consisting of a plastic pipe, an overturned ceramic flowerpot, or even a large glass jar, all of which can imitate tunnels. A female can produce up to 2000 eggs. Due to their small size, the young should first be fed with the smallest foods available (rotifiers and diatoms). Larger items can then be provided, such as freshly hatched Artemiaand microworms. Usually after about two weeks, parental care peters out, and the young should then be separated from the adults.

An Intriguing Fish to Own

The eartheaters’ assets include a variety of shapes, sizes, and colors, engaging social behaviors, varied and interesting breeding strategies, and diligent parental care. Furthermore, these are long-lived fish that can live a dozen years or more. Among the downsides, we must count the difficulty of keeping certain species in excellent health (some Satanoperca), the necessity of having very large tanks (for AcarichthysS. lilith, S. daemon, Geophagus altifrons), and, for the genus Gymnogeophagus, the need for periodic temperature reduction.

For the beginning of your adventure with these interesting cichlids, I would suggest some species of the genus Geophagus due to their ability to adapt to various physical and chemical water parameters, tolerance with regard to mistakes in maintenance, and ease of reproduction. Having acquired some experience, you can turn your attention to more demanding eartheaters such as SatanopercaBiotodoma, or Acarichthys.

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