Argyrostictus Eartheater (Geophagus argyrostictus)

Choose Geophagus argyrostictus, the silver-spotted eartheater of the Xingu

Geophagus argyrostictus is a sand-sifting South American cichlid from the rio Xingu, a great clear-water tributary that joins the Amazon from the south in Pará, Brazil. Its name means "silver-spotted": as the fish grows past about 7–8 cm, the scales on the front of its flanks turn silvery and reflective. Our photographs show an olive body spangled with rows of small turquoise spots, a rounded dark spot in the middle of each flank and long, spotted fins with fine reddish edges.

Sven Kullander described the species in 1991 from a rocky pool near a waterfall at Belo Monte. Seriously Fish notes that it had been collected long before and misidentified in 1976 as Geophagus surinamensis, a mix-up that still runs through the trade, where many eartheaters are sold under that name. It is widespread in the Xingu and its tributary the rio Iriri, and FishBase also lists the Curuá basin. Colour varies with collecting locality; populations known in the hobby include 'Altamira', 'São Félix' and 'Tamandua Zinho'.

Check the identification points

For a UK buyer this is a fish for the dedicated South American cichlid keeper: rarer than the common eartheaters, more spirited than most of its relatives and happiest in a warm, spacious aquarium with a group of its own kind. Seriously Fish describes it as relatively rare in the hobby and sometimes available from specialist retailers; FishBase notes it is becoming better established in the aquarium trade.

Know exactly what you receive

One purchase supplies one live Geophagus argyrostictus. The size option is "Standard": the fish is sent at the size currently available, which is a young fish well below the adult size given below. Sex is not chosen or guaranteed. Seriously Fish states that juveniles cannot be sexed by eye unless they are spawning.

The photographs show the species, not the individual you will receive. Young fish have not yet developed the silver flank scales that give the species its name, colour varies between localities, and any fish looks paler for a few days after a journey.

Decide how many to order

• A group of five to eight: the number Seriously Fish gives as the minimum purchase. In smaller groups weaker individuals can become the target of excessive aggression.
• Order them together: young fish introduced at the same time settle their pecking order more evenly than fish added one by one.
• Expect pairs to form later: starting with a group of youngsters and letting pairs form naturally is the route Seriously Fish recommends for breeding.

Read our delivery and Live Arrival Guarantee details before you order, and have the aquarium fully matured and heated before the fish arrive.

Plan the aquarium around an 18 cm adult

Seriously Fish gives a maximum of 180 mm standard length, which is measured from the snout to the base of the tail, and FishBase records 24.2 cm total length, tail included. Fully mature males tend to be a little larger than females, and dominant males often develop a pronounced hump on the forehead.

Seriously Fish asks for an aquarium base of at least 150 × 45 cm, about 304 litres, to house the species long-term. OATA independently gives at least 300 litres for American cichlids over 15 cm. Treat that as the floor and plan larger for the recommended group: a longer and deeper base gives every fish room to hold a patch of sand and to retreat.

Run a three-step space check

1. Measure the floor: the base area decides how many territories fit, so length and depth matter more than height.
2. Count the fish: a group of five to eight large eartheaters needs space beyond the minimum base, plus room for any companions.
3. Size the equipment: our tank volume calculator turns your dimensions into litres, which you need for the filter, heater and weekly water change.

Place the aquarium away from draughts, radiators and windows, and use a reliable heater. This is a warm-water fish, and a stable temperature matters more to it than to many community fish.

Recreate a clear-water Xingu shore

Part of the type series was collected near Altamira from rocky shore areas with clear water. Seriously Fish adds that the species prefers clear water and gently sloping margins around shores and islands, over sand, fine gravel and mud, with scattered rocks, submerged roots and branches in places; it has also been found in floodplain lakes. In the aquarium, the most essential item is a soft, sandy substrate. Gravel or small pebbles can stop it feeding, damage its gill filaments and even be swallowed.

Divide the floor by function

Seriously Fish advises against leaf litter in an eartheater aquarium: the constant sifting keeps broken-down leaf material in suspension, which looks untidy and can block filters and pumps. Stand rocks on the glass before adding sand so the fish cannot undermine them.

Hold the water warm, soft and stable

Seriously Fish gives 26–30°C, pH 6.0–7.5 and 1–10 dGH, and FishBase gives 25–30°C. It also warns that these cichlids are extremely susceptible to deteriorating water quality and to swings in water chemistry. That temperature range sits above OATA's general guidance of 22–27°C for American cichlids, so this species needs a warmer aquarium than many South American community set-ups.

Match your water to the targets

UK tap water is soft across much of Scotland, Wales and north-west England and hard in much of the south and east. In a soft-water area you can usually use conditioned tap water as it is. In a hard-water area, mixing tap water with reverse-osmosis water lowers the hardness; make the blend the same at every water change so the chemistry does not swing. Use a conditioner on all new water, as OATA advises. Our water matcher compares your readings with this range, our water chemistry guide explains GH, KH and pH, and our guide to tropical tank temperature covers heater sizing and placement.

Over-filter and change water every week

Seriously Fish recommends over-filtering an eartheater aquarium with external canister filters, a sump or both, and changing at least 50–70% of the water every week. Its equipment note for a tank of about 304 litres suggests two filters rated around 610–760 litres per hour each, and roughly 175–250 W of heating split across two heaters. If maintenance falls short, it warns, head and lateral line erosion and stunted growth can follow.

Two details matter with sand-sifters. First, mechanical filtration should trap the fine particles the fish stir up, because sand running through a filter blocks and wears it. Second, high flow rates should be avoided, so angle the filter returns along the glass and the surface rather than across the sand.

Follow a weekly routine

1. Test ammonia, nitrite, nitrate and pH; OATA recommends at least one test a week.
2. Change 50–70% of the water with conditioned water matched for temperature and hardness.
3. Siphon debris from the top of the sand without lifting the whole layer.
4. Rinse the mechanical media in old tank water, never under the tap.
5. Confirm the temperature is still steady within 26–30°C.

Our aquarium filtration guide explains how to combine canister filters and how to set the flow.

Feed small sinking meals several times a day

Geophagus feed by taking mouthfuls of sand and sifting them, passing the rest out through the gills and mouth. Seriously Fish reports that wild stomach contents are mostly small aquatic and terrestrial invertebrates, seeds, organic detritus and sediment, and that even adults cannot properly swallow larger items. Once settled, the fish rise to take food when it is added but go on sifting the rest of the time.

Build one measured meal

• Staple: high-quality, fine-grade sinking granules or small pellets; some of them should be rich in vegetable matter such as spirulina.
• Small frozen foods: thawed bloodworm, brine shrimp or mosquito larvae.
• Homemade option: Seriously Fish reports success with gelatine-bound mixes of dry food, puréed shellfish, fruit and vegetables, cut into small discs.
• Timing: three to four small portions a day, which Seriously Fish says gives the best growth and condition.
• Portion: each meal cleared in a few minutes; siphon anything left on the sand.

Spread food across the sand so every fish in the group can sift, not only the dominant one.

Settle the group into a mature aquarium

Seriously Fish is clear that these cichlids should never be introduced to a biologically immature aquarium. Before the fish arrive, ammonia and nitrite must read zero and the heater must have held 26–30°C for several days. Use OATA's method: lights off, float the sealed bag for about 10 minutes, add small amounts of tank water over up to 20 minutes, then net or pour the fish in with as little bag water as possible. Our page on acclimatising new fish shows each step, and our cichlid care guide covers the basics for all cichlids.

Use a first-week checkpoint plan

Some chasing as the group sorts out its order is normal. A fish that is constantly hounded, hides all day or stops feeding needs more cover, more space or a separate tank.

Pick tank mates for a spirited eartheater

Seriously Fish describes G. argyrostictus as markedly more aggressive than most other Geophagus, though several can share a larger aquarium. It ignores smaller fish, so schools of small characins can be added without fear of predation, but other cichlids are generally best avoided. Seriously Fish knows of cases where it has lived long-term with members of the G. surinamensis group, so a very large aquarium with a calm surinamensis-group eartheater is possible for experienced keepers.

Screen each companion

Seriously Fish's list of fish collected alongside it in the Xingu also includes Satanoperca jurupari, our Demon Eartheater, though a second sand-sifting cichlid needs a very large floor. Check any planned mix with our tank mates tool, browse all South American cichlids, the full South American cichlid range and our Geophagus eartheaters, or look through our rare and collector fish.

Watch for problems early

OATA describes a healthy fish as having clear, bright eyes, undamaged fins, intact scales, no ulcers or bumps, normal swimming and steady breathing; clamped fins, flicking against décor and shimmying are warning signs. For this species, Seriously Fish adds two long-term warnings: head and lateral line erosion and stunted growth, both linked to poor maintenance.

Pair each sign with an action

Most problems in large eartheaters trace back to water quality, so test, record and correct the water before reaching for treatments.

Breed it in a dug pit

Unlike most Geophagus, which brood their eggs or young in the mouth, G. argyrostictus is a substrate spawner with a fairly simple strategy. Seriously Fish reports no particular trigger beyond a good diet and large weekly water changes, and notes that the fish can take at least a year to mature.

Set up for a spawning

1. Grow a group: start with young fish and let pairs form naturally, since sexing young fish is not possible.
2. Watch the courtship: fin flaring, circling, gaping and head jerking signal a pair forming.
3. Expect a pit: the pair digs a large pit, may defend it for days and then chooses a smaller site inside it, usually a solid object that they clean thoroughly.
4. Leave them in peace: up to 200–250 eggs are laid; the female tends them while the male defends the territory, and other fish are not tolerated nearby.
5. Raise the fry: the eggs begin to hatch after about three days (70 hours at 27°C); the female may help the fry out of the eggs and spit them into cover. Feed powdered dry food, brine shrimp nauplii or microworm once they swim freely.

In a community aquarium, remove either the tank mates or the fry, because the young are easy prey even though both parents defend them for some time.

Answer Geophagus argyrostictus buying questions

What is Geophagus argyrostictus?

It is a sand-sifting eartheater cichlid described by Kullander in 1991 from the rio Xingu system in Brazil, including the rio Iriri. The name means "silver-spotted", after the silvery reflective scales that larger fish develop on the front of the flanks. It has a rounded dark spot in the middle of each flank and a dark stripe below the eye that shows mainly on the cheek.

How big does Geophagus argyrostictus grow?

Seriously Fish gives a maximum of 180 mm standard length, measured without the tail, and FishBase records 24.2 cm total length. Plan for a large adult even though you receive a young fish.

What size aquarium does it need?

Seriously Fish asks for a base of at least 150 × 45 cm, about 304 litres, to house it long-term. Because it should be kept in a group of five to eight, plan larger than that minimum for a group.

What water temperature does it need?

Warm, steady water: Seriously Fish gives 26–30°C and FishBase 25–30°C. That is warmer than OATA's general 22–27°C for American cichlids, so check that your heater can hold the upper end in winter. Seriously Fish gives pH 6.0–7.5 and 1–10 dGH.

Is Geophagus argyrostictus aggressive?

It is markedly more aggressive than most other Geophagus, according to Seriously Fish. It ignores smaller fish, so schools of small characins are safe, but other cichlids are generally best avoided. A group of five to eight spreads the squabbling; in smaller groups weaker fish can be picked on.

Is it a mouthbrooder?

No. Unlike most Geophagus, it is a substrate spawner: the pair digs a large pit, lays up to 200–250 eggs on a solid surface within it and guards eggs and young.

Does it need sand?

Yes. Seriously Fish calls a soft, sandy substrate the most essential item of décor, because the fish feeds by sifting mouthfuls of sand. Gravel can stop it feeding, damage its gills and even be swallowed.

How many fish come with one purchase?

One live fish of the standard size currently available, normally a young fish well below adult size. Sex is not chosen or guaranteed, and young fish cannot be sexed by eye.

Consult the care references

• Seriously Fish: Geophagus argyrostictus — names, Xingu distribution and habitat, size, aquarium base, water values, maintenance, diet, behaviour, sexing, substrate spawning and identification.
• FishBase: Geophagus argyrostictus — maximum recorded length, temperature, distribution, spawning mode and IUCN status.
• OATA: How to look after American cichlids — UK group-level guidance for American cichlids: water values, tank sizes, substrate, heating, acclimatisation, health checks and weekly maintenance.
• Tropical Fish Co delivery policy — current dispatch days and Live Arrival Guarantee terms.