Classification
Order: Cyprinodontiformes
Family: Poeciliidae
Distribution:
Native to southeastern Mexico, central Guatemala, southern Belize, and northwestern Honduras. Its known range extends south from the Rio Nautla (alternatively referred to as the Rio Filobobos) in central Veracruz state, Mexico, to the Rio Usumacinta drainage in Guatemala, the Rio Sarstun (aka Sarstoon) at the border between Guatemala and Belize, and the rios Copan and Chamelecon in Honduras.
Habitat:
Natural populations are found in various types of habitat from sea level to around 1500 m altitude, including fast-flowing, rocky streams, to springs, ditches, ponds, and rivers containing clear to turbid water. In most cases the water is less than 1.5 m deep and there is no aquatic vegetation.
In flowing water adults tend to congregate in areas with greater current, while juveniles and subadults display a preference for quiet marginal zones.
Introduced populations may occur in springs, streams, rivers, canals, ditches, pools, artificial reservoirs and other environments, and the species exhibits a degree of tolerance to polluted conditions. Where X. hellerii occurs in large numbers outside its natural range it is thought to exert a number of negative impacts on native species and ecosystems.
Maximum Standard Length:
Males up to 14 cm (5.5 inches), females up to 16cm (6.2 inches) TL.
Aquarium Size:
An aquarium with surface dimensions of 120 x 30 cm or equivalent should be the smallest considered.It is advised to find a filter which has a water flow between 4-5 times the volume of your aquarium.
Maintenance:
Choice of decor is not especially critical though it tends to look best in a heavily-planted set-up with a dark substrate. Wild forms should also suit an aquarium arranged to resemble a flowing stream with water-worn rocks and small boulders. The addition of some floating plants and driftwood roots or branches to diffuse the light entering the tank also seems to be appreciated and adds a more natural feel. Filtration does not need to be particularly strong though it does seem to appreciate a degree of water movement.
Water Conditions
Temperature: 16 – 28 °C
pH: 7.0 – 8.0
Hardness: 179 – 447 ppm
Diet:
Stomach analyses of wild specimens have shown it to be a generalised omnivore, feeding on a range of aquatic and terrestrial invertebrates, organic detritus, algae, and other plant material. In the aquarium it is unfussy and will accept just about anything offered. Offer a balanced diet comprising good quality dried products along with small live and frozen foods such as Daphnia, Artemia and chironomid larvae (bloodworm).
Sexual Dimorphism:
Adult males tend to be smaller than females and possess a prominent gonopodium, plus the characteristic extension of the lower caudal-fin lobe. In some ornamental strains the upper caudal-fin lobe or other fins may also be extended, however, including in females.
Reproduction:
Like other members of the viviparous family Poeciliidae, male Xiphophorus have a gonopodium, essentially a modified anal-fin, which is used for internal fertilisation of females.
The reproductive behaviour of Xiphophorus is well-studied, and females are known to exhibit preferences for numerous physical and behavioural traits such as sword length (long, short, or without), colour pattern, body size, vertical barring on the body, chemical cues and specific nuptial behaviours. In some cases females show preferences for male traits of other species. Male behaviour is designed to both attract mates and drive away rivals, while some individuals, known as ‘sneakers’,
Females are also capable of storing viable male sperm for months,
