Classification:
Order: Perciformes
Family: Cichlidae
Distribution:
Type locality is ‘above Blanche Marie Valen, Nickerie District, Suriname’ in the Nickerie river drainage, northwestern Suriname. It’s also known from the Courantyne (aka Corantijn) system which forms the border between western Suriname and Guyana for much of its course.
Habitat:
Suriname has a tropical climate with well-defined annual weather patterns, year-round high temperatures and two distinct wet seasons; the first, more minor, between December and February and the second from April to June. During these periods flow rate and depth of rivers can vary enormously, even on a daily basis, and turbidity also increases. This species tends to inhabit gently sloping marginal zones around shores or islands with substrates of sand, fine gravel and mud though it was first collected from a rocky pool above the Blanche Marie waterfalls on the Courantyne river. Depending on locality other habitat features can include scattered rocks, submerged tree roots and branches and presumably the fish are found in or very close to stretches of rapids at certain times of year.
Maximum Standard Length:
The largest officially-recorded wild specimen measured 138mm but this species is known to reach 180 – 200mm in captivity.
Aquarium Size:
An aquarium with a base measuring 180 x 60cm or more is required to house a group long-term.
Maintenance:
The most essential item of decor is a soft, sandy substrate so that the fish can browse naturally. Coarser materials such as gravel or small pebbles can inhibit feeding, damage gill filaments and even be ingested with the potential of internal damage or blockages. Additional furnishings are as much a case of personal taste as anything else but the most favoured set-ups tend to feature relatively dim lighting plus some chunks of driftwood and scattered roots or branches. Leaf litter is a typical feature of the natural environment but not really recommended in aquaria because the feeding behaviour of Geophagus spp. tends to cause an excess of partially-decomposed material in suspension which not only looks unsightly but can block filter and pump mechanisms. One or two flattish, water-worn rocks can also be included to provide potential spawning sites if you wish.
Water quality is of the utmost importance since these cichlids are extremely susceptible to deteriorating water quality and swings in chemical parameters so should never be introduced to a biologically immature aquarium. The best way to achieve the desired stability is to over-filter the tank using a combination of external canister filters and/or a sump system and perform minimum weekly water changes of 50-70%. If the maintenance regime is insufficient health issues such as head and lateral line erosion or stunted growth can occur. Mechanical filtration should also be tailored to trap small particles stirred up by the fish as sand can cause blockages and wearing issues with filter mechanisms if allowed to continually run through the system. High flow rates should be avoided so position filter returns accordingly.
Water Conditions:
Temperature: Prefers warm conditions within the range 26 – 30°C. Air temperatures in Suriname are near constant year-round with an annual average of 27°C.
pH: 5.0 – 7.0
Hardness: 18 – 179 ppm.
Diet:
Geophagus spp. are benthophagous by nature, employing a method of feeding whereby mouthfuls of substrate are taken and sifted for edible items with the remaining material expelled via the gill openings and mouth. For this reason they’re commonly termed ‘eartheaters’ and the provision of a suitable substrate is essential to their long-term well-being. Once settled they readily rise into the water column when food is introduced but continue to browse normally at other times. Even as adults these cichlids seem unable to properly ingest larger food items meaning the diet should contain a variety of high quality, fine-grade prepared foods plus small live or frozen bloodworm, Tubifex, Artemia, mosquito larvae, etc. At least some of the dried products should contain a high proportion of vegetable matter such as Spirulina or similar. Home-made, gelatine-bound recipes containing a mixture of dried fish food, pureed shellfish, fresh fruit and vegetables, for example, are proven to work well and can be cut into bite-sized discs using the end of a sharp pipette or small knife. Rather than a single large meal offer 3-4 smaller portions daily to allow natural browsing behaviour as this seems to result in the best growth rate and condition.
Behaviour and Compatibility:
Unless breeding this species is surprisingly peaceful and will not predate on fishes larger than a few millimetres in length. Suitable tank mates are far too numerous to list but include most peaceful species enjoying similar environmental conditions. Best avoided are aggressive or territorial substrate-dwelling species, or those requiring harder water. Some aquarists keep Geophagus spp. alongside freshwater stingrays of the genus Potamotrygon which in many cases has proven successful but in some has resulted in them disappearing at night (!). G. brachybranchus is gregarious and tends to exist in loose aggregations unless spawning, with juveniles in particular displaying strong grouping instincts. A group of 5-8 individuals should be the minimum purchase and these will form a noticeable dominance hierarchy. When maintained in smaller numbers weaker specimens can become the target of excessive antagonism by dominant individuals or the group may fail to settle and behave nervously.
Sexual Dimorphism:
No external differences have been observed except during spawning when the ovipositor of the female is visible.
Reproduction:
Substrate-spawning, larvophilous, biparental mouthbrooder that has been bred in aquaria. There doesn’t appear to be any particular trigger for the spawning process with the main requirements being good diet and stringent maintenance regime involving relatively large weekly water changes. Since accurate sexing is very difficult it’s best to begin with a group of young fish and allow pairs to form naturally. A degree of patience is also required since it can be at least a year until they become sexually mature. Courtship is relatively unobtrusive consisting of fin flaring, circling, gaping and head jerking displays, and when ready to spawn a pair will select a suitable site. This is normally a piece of decor such as a flat rock or section of driftwood although it’s not unknown for the base of the aquarium to be used, and once chosen the area is cleaned and defended against intruders. Spawning occurs in typical substrate–spawning style with the female laying one or more rows of eggs before the male moves in to fertilise them, the process being repeated numerous times over a period of several hours. Post-spawning the female stays close to the eggs, tending and defending them against intruders while the male is responsible for defence of the surrounding territory. After around 72 hours the eggs hatch and fry immediately taken into the mouth of the female although on some occasions both parents may be involved from the start. Once the fry are free swimming brood care and defence is shared although this varies depending on the male with some individuals becoming involved earlier and others not at all. Some females therefore continue to hold all the fry or may even be driven away by the male to care for them alone. In other cases both parents hold fry simultaneously or exchange the entire brood between one another on a regular basis, with such transfers tending to take place in a sheltered location such as a depression in the substrate. When not brooding the adults will normally feed, and may even take some small morsels while holding fry.
The fry become free swimming at 8-11 days of age and the parents begin to release them to feed, initially with caution but for increasingly longer periods. If danger is sensed the fry are shepherded back into the adults’ mouths, with rapid movement of the ventral fins appearing to act as a signal. As time elapses and the fry grow they may only return to their parents’ mouths at night while the size of the territory becomes correspondingly larger. They’re easily-fed, accepting good quality powdered dry foods, Artemia nauplii, microworm, etc., as soon as the free-swimming stage is reached. If maintaining the adults in a community situation it’s recommended to remove brooding females as the fry become easy prey for other fishes, including conspecifics, once released.
Notes:
This species is generally rare in the aquarium hobby though oddly appears to be one of the commoner species in Australia where it’s often referred to by the vernacular name ‘black-throated eartheater’. It’s a member of the putative G. surinamensis ‘group’ of closely-related species within the genus and can be identified by a combination of characters including: presence of dark preopercular markings; no vertical bars on the flanks even when stressed/preserved; base of filaments on the first gill arch mostly covered by a flap of skin; exposed part of branchiostegal membrane blackish-coloured; caudal fin in adults reddish with a variable pattern of large, opaque to clear spots.
