Endler's livebearers are very hardy and adaptable, which is one reason they're well suited to many types of aquariums.
Endler’s livebearer, or Poecilia wingei, are a close relative of the common guppy (Poecilia reticulata). They are so closely related, in fact, that many strains of Endler’s and guppies are actually hybrids. Endler's livebearer were originally collected in Venezuela and were introduced to the aquarium hobby in the mid 1970's. Endler’s today come in a variety of color morphs and males are highly variable, even among the same kind. All of them are smaller than the average fancy guppy and are well suited to nano aquariums. The species name “wingei” is in honor of Dr. Ojvind Winge.
A pair of Endler’s livebearers can be housed in an aquarium as small as 2.5 gallons, however a 5 gallon or larger is beneficial, especially given how fast they reproduce. You may keep only males together to avoid recruitment over time. They prefer a planted aquarium for added cover, but are not picky about decor or substrate.
Endler’s thrive in almost every temperature. Their preferred range is 72-84 degrees. The only caveat is that the warmer you keep these fish, the higher their metabolism and therefore shorter their lifespan. Usually shooting for the low to mid-70’s is the best bet.
Endler’s livebearers prefer a pH of around 7.0-8.5, but anything above 7.5 is ideal. Like most livebearing fish, they thrive in harder water. If your water is naturally too soft or if you are reconstituting RO water, you may wish to buffer it with Seachem Alkaline buffer and Seachem Equilibrium.
To maintain an Endler’s livebearer aquarium, it's recommended you do weekly water changes of 25-50% and monthly filter maintenance. Monthly maintenance includes rinsing the bio media/sponges in treated tap water (to avoid killing the beneficial bacteria). If you are using chemical media such as carbon, this should be changed out once a month as well. Water changes are best done with a gravel siphon to pull any hidden debris out of the substrate. Whenever water is changed, make sure the clean water going into the aquarium is a similar temperature and to treat it with a dechlorinator if you are using tap water.
Endler’s livebearers are highly compatible with other nano fish and each other. It is advised, however, that you avoid keeping regular fancy guppies (Poecilia reticulata) with Endler’s (Poecilia wingei). This is to avoid crossbreeding. You may also wish to keep different varieties of Endler’s separate, unless you are just keeping males. This will preserve their genetic integrity. Otherwise, Endler’s go great with small loaches, catfish (such as Corydoras and plecos), small tetras, rasboras, and danios. They also pair well with small freshwater shrimp (Neocaridina and Caridina).
Males and females of Endler’s livebearer stay relatively small. Males barely get over an inch in size as adults. Females are the bigger of the two, and can get to almost 2” in total length.
Endler’s livebearers are omnivores and will eat practically anything they can fit in their mouths. Because their mouth is oriented towards the surface of the water, they especially appreciate floating foods such as quality crushed flake or micro pellets. They will also go after sinking foods such as Repashy gel diets and shrimp pellets or algae wafers. Frozen brine shrimp or daphnia make a great treat, as do live baby brine shrimp.
As stated above, sexing is fairly straightforward with the Endler’s livebearer. Females are bigger than males and far less pretty. However, if ever in doubt, the fish can be sexed as early as three weeks of age by simply looking at the anal fin. Males have what is known as a gonopodium, which means they have a more pointed anal fin. Females do not possess this, and simply have a fan shaped anal fin. Females will also have what is known as a “gravid spot”, which is a dark area just before the anal fin on the belly that indicates she is carrying fry.
Endler’s livebearers are among the easiest fish to breed. They may even be easier than their cousin, the guppy, in the sense that their mouth is usually too small for them to immediately eat their offspring at birth. Being livebearers, these fish will become gravid after internal fertilization via the male’s gonopodium. The eggs will develop within the female and after about a month, she will give live birth to anywhere from 5-20 young. At birth, the livebearer fry are able to immediately accept crushed flake food, as well as live baby brine shrimp and microworms. If you want the best survival of fry, provide plenty of floating plants such as hornwort, Riccia, or water lettuce and keep them in a species-only setup, as other fish may find the fry quite tasty. You may also choose to remove fry as you find them and raise them in a separate breeding tank or in a breeder net or breeder box attached to the main aquarium. Because these fish breed constantly and females are able to retain sperm, if you have females you will almost certainly get fry. Thus, this is a great starter fish for anyone looking to breed aquarium fish at home.
Aqueon - Setting Up A Livebearer Aquarium