Greenstreaked eartheater

The greenstreaked eartheater, known in the trade as the cupid cichlid, is a graceful South American cichlid from the soft, acidic waters of the Amazon, Orinoco, and Essequibo river basins across Peru, Brazil, Bolivia, and Guyana. Its body is a subtle blend of silver, gold, and olive, illuminated by iridescent green-blue horizontal streaks across the flank — a pattern that intensifies with maturity and mood. A prominent dark spot sits high on the flank just below the dorsal fin, and the elongated rays of the dorsal fin stream back elegantly in dominant males. The species reaches about 12 to 14 cm total length, with males larger and more colourful than females.

Biotodoma cupido is a gregarious eartheater cichlid — unlike many cichlids, it does best in groups of five to eight individuals, where a natural hierarchy forms and fish display their best colours. They are generally peaceful for cichlids, though spawning pairs can become territorial. Their common name comes from their feeding behaviour: they take mouthfuls of sand, sift through their gill rakers for edible bits, and expel the rest through the gill openings. This constant sifting means a sand substrate is mandatory — gravel will injure their delicate gill filaments. Suitable tankmates include other peaceful South American cichlids, larger tetras, Corydoras catfish, and plecos. Their diet should be primarily carnivorous, with high-quality sinking cichlid pellets, frozen bloodworms, brine shrimp, mysis, and occasional vegetable matter.

A group of greenstreaked eartheaters requires a spacious tank of at least 300 litres for a group, though a single pair can manage in a 114-litre setup. The water must be soft and acidic — pH 5.0 to 7.0, with a temperature of 23 to 28°C. They are sensitive to water quality and require excellent filtration with regular partial water changes. Fine sand substrate is essential for their natural sifting behaviour. In the aquarium, they are substrate spawners: a bonded pair will clear a flat stone or depression in the sand and spawn on it, with both parents guarding the eggs and later the free-swimming fry. The fry are large enough to accept baby brine shrimp from hatching. With stable conditions and a varied diet, these elegant cichlids can live eight years or more, rewarding the patient keeper with a display of subtle, ever-changing colour and fascinating natural behaviour.