Range, geographic variants and habitat
The species occurs in the soft, acidic warm waters of the Mamoré and Guaporé river drainages in Bolivia and Brazil. Whether one morph of M. altispinosus, known to aquarium hobbyists as Mikrogeophagus sp. "Zweifleck/Two-patch", found in the upper Rio Guaporé in Brazil is a different species remains unclear The type locality is the Rio Mamoré at San Joaquin (Beni Province, Bolivia). In its natural habitat the species occurs in permanent freshwater streams and pools.
Appearance and sexual dimorphism
The species is similar in profile to the larger geophagine cichlids. Maximum size is approximately 8 centimetres (3.1 in.). The head and front half of the body is yellow fading to olive-grey at the rear. There is a vertical black band through the eye and six faint transverse stripes along the body the third stripe is dark at its centre. The first few rays of the dorsal fin are black and both the dorsal and caudal fin are edged in pinky-red. The anal and pelvic fins are the same shade of red throughout with bright blue rays and dots.
The species displays only limited sexual dimorphism, mature males being slightly larger and in some cases showing longer extensions on both the caudal fin and the posterior of the dorsal fin.
Diet
Omnivorous. Sifts the substrate for plant material and small organisms.
Reproduction
Bolivian rams are biparental open spawning cichlids. Limited data are available on reproduction in the wild, in captivity, however, courtship is known to involve various body movements including head shaking, quivering and preparation of spawning sites, including shallow pits. These behaviours are mainly undertaken by the male and in aquaria are known to last approximately 48 hours.
After courtship, the female will deposit some 100-200 ovoid brownish coloured eggs on the chosen surface, normally a flattened stone. The eggs are laid in lines, when the female has laid one line, the male will pass over it and fertilise the eggs, the female then continues on to the next line and so on until egg laying is complete. In aquariums at 27 ºC (80.5 ºF) eggs take approximately 60 hours to hatch. During this time, the clutch is primarily cared for by the female who fans the eggs and often adds sand to the clutch, possibly to camouflage the eggs. Newly hatched larvae are transported via the mouths of the parents to the shallow pits dug by the male during courtship and moved regularly between pits. The fry become free-swimming after 7 days and are lead about in a dense school by the parents for foraging.
In the aquarium
Although less popular than its close relative Mikrogeophagus ramirezi, the Bolivian ram remains a commonly encountered cichlid for the aquarium. The species is also more tolerant of lower temperatures (22–26 °C, 72–79 °F) and a greater range of water chemistries than M. ramirezi. For these reasons, M. altispinosus can be kept in some community aquariums, however, assertive, active or aggressively-feeding fish are not ideal companions for this relatively shy species.
An aquarium which mimics the natural environment of the species, ie: soft, acidic water with hiding places in the form of dense planted regions, or bogwood is recommended. Aquarists classify M. altispinosus as a dwarf cichlid and as such it can be kept in relatively small aquariums, with minimum volumes being approximately of 80 litres (20 gallons). In captivity the species is an unfussy feeder and readily accepts many commercially available fish foods.
