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(G. S. Myers & Harry, 1948)
The ram cichlid, Mikrogeophagus ramirezi, is a species of freshwater fish endemic to the Orinoco River basin, in the savannahs of Venezuela and Colombia in South America. The species has been examined in studies on fish behaviour and is a popular aquarium fish, traded under a variety of common names, including ram, blue ram, German blue ram, Asian ram, butterfly cichlid, Ramirez's dwarf cichlid, dwarf butterfly cichlid and Ramirezi. The species is a member of the family Cichlidae and subfamily Geophaginae.
Appearance and sexual dimorphism
Wild ram cichlids are often more colorful than the tank-bred fish, which suffer from poor breeding and also being injected with hormones for more color, although this makes as many as one in four males infertile. Male specimens of the ram usually have the first few rays of the dorsal fin extended, but breeding has made some females also show this. When close to spawning, female rams have a pink or red blush on the abdomen. Females also have a blue sheen over the spot just below the dorsal fin, or a sparse scattering of blue scales in the upper half of the dark spot, and males do not show this. Males reach a maximum length of 7 cm, and females are usually slightly smaller.
Distribution and habitat
The natural habitat of M. ramirezi is warm (25.5-29.5°C, 78-85°F), acidic (pH 5) water courses in the llanos savannahs of Venezuela and Colombia. The water is generally slow-flowing, contains few dissolved minerals, and ranges in colour from clear to darkly stained with tannins. The species is typically found where cover in the form of aquatic or submersed vegetation is available.
Once sexually mature, the fish form monogamous pairs prior to spawning, and the males do not tolerate other males. The species is known to lay its small 0.9 - 1.5 mm, adhesive eggs on flattened stones or directly into small depressions dug in the gravel. Like many cichlids, M. ramirezi practices biparental brood care, with both the male and the female playing roles in egg-tending and territorial defense. Typical clutch size for the species is 150-300 eggs, though clutches up to 500 have been reported. Parental ram cichlids have been observed to fan water over their eggs, which hatch in 40 hours at 29°C (84°F).
The larvae are not free-swimming for five days, after which they are escorted by the male or the female in a dense school for foraging.
Taxonomy, collection, and etymology
The ram cichlid is named after Manuel Ramirez, an early collector and importer of the species for the aquarium trade. George S. Myers and R. R. Harry (1948) originally described the species as Apistogramma ramirezi, though the species was later moved to and from various genera, including: Microgeophagus, Papiliochromis, Pseudoapistogramma, and Pseudogeophagus.
In the aquarium
Numerous strains of M. ramirezi have been developed in Asia for the fishkeeping hobby. These include numerous xanthistic forms, known as gold rams or electric blue , along with larger, high-bodied, and long-finned varieties. Many of these varieties suffer from lower fertility, health problems, or reduced brood care in comparison to wild-type specimens.
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