Care
A fish with a very long aquarium history, the Southern platyfish or Moon platy found its way to Europe around 1900 and was soon bred into a range of colour forms that are remarkably different from their drabber wild ancestors. Their ability to hybridise with closely related species such as Swordtails, as well as Variatus platies, made the transfer of characteristics possible and now there's a huge overlap between all of these fishes. This can be seen in the number of breeds which have both platy and swordtail forms, such as red, calico, red wagtail, comet etc. This makes the use of scientific names a little complex for these fishes and it may be best to view all but the most primitive of breeds as Xiphophorus hybrids.
Wild platies are found in slow-moving habitats with plenty of vegetation, normally in areas where the local geology means that conditions are hard and alkaline. Despite over a century of domestication, they remain fishes of hard water and will struggle in acidic conditions.
In typical livebearer fashion males can be persistent, and these sociable fish are best kept in groups where males are outnumbered by females. As well as courting females, males will display and pursue their rivals and are best kept in odd numbers in small aquaria where this behaviour may otherwise lead to constant friction between two evenly matched fishes. As females will produce fry regularly after a single mating, it's best to keep a group of males if breeding is to be avoided. Despite wild fish having two accepted common names, most of the time you'll see aquarium forms described by their colour or breed. All of these are compatible and will happily mix, making a community of platies one of the most diverse and varied of any aquarium fish. In these mixed situations, fry may be very different to their parents thanks to the potential for cross breeding and the number of genes involved in all of these colour and finnage forms.
Feeding
Omnivorous. Feed a good quality flake food, small frozen foods such as mosquito larvae and daphnia, and keep with fast-growing plants which the fish will browse on, mostly consuming algae and biofilm.
Breeding
Very easy. Platies are livebearers, which means that the females give birth to live young. After fertilisation occurs, the female gestates for 25-30 days, after which time she will give birth to between 20 and 80 free-swimming fry. Females store sperm and one mating will give rise to multiple broods. The adults (and other fish species in the aquarium) will predate on the fry if not separated. However, a few will normally manage to survive onto adulthood when kept in a well planted aquarium with lots of natural hiding places. At the lower end of their temperature range, breeding becomes less frequent and this may be a useful way to slow down population growth.
