With guppies, there is just one species that comes in many colours and tail types. With apistogrammas, there are many different species and some of them have different coloured varieties.
The different species have different water requirements; though they all do best in soft acidic water, a couple of species are fine in harder, less acidic water. But none should be kept in hard alkaline water.
Some should be kept as m/f pairs, some are harem breeders which can be kept a a m/f pair or several females to one male.
The two most common in shops are the easiest species -
Apistogramma cacatuoides (cockatoo cichlid) and
A. agassizii (Agassizi's cichlid). Both of these are harem breeders and come in different colours.
One thing about cockatoo cichlids to be aware of - when they are kept with multiple males in a tank, such as the shop tank, there will be one dominant male. Subordinate males often take on female colouring and fin shape to avoid aggressiveness from the dominant male. They look just like females.
I once bred cockatoo cichlids, keeping a male and 2 females and giving away the rest. Both females had short fins, black on their pelvic fins and were bright yellow. Until one of them turned grey and grew fin extensions.......
