Endler vs guppy

Check the size first. An adult male Endler is about an inch long, and next to a male guppy it looks like a scale model. Then look at the tail. Endlers carry a short tail, sometimes with a thin sword along the top or bottom edge. Most fancy guppies carry a tail nearly as big as the body. A black bar or spot in the middle of the flank, with orange and metallic green around it, points to an Endler.

Telling the males apart is usually easy. The trouble starts with the females and with what the label on the shop tank really means.

Size and water numbers

These numbers come from the Endler's livebearer and guppy care pages. The water columns barely differ. Tank size and bioload are where the two fish split.

Telling males and females apart

Look at males from the side while they display. An Endler male has a slim, slightly pointed body and a tail that is short compared to the body. Common Endler patterns include a black spot or bar under the dorsal fin, orange patches near the tail, and green or blue shine along the flank.

Fancy guppy males are bigger, deeper in the body, and bred for tails. A delta or fan tail on a show guppy can be as long as the fish. Feeder guppies and wild-type guppies have shorter fins and can pass for Endlers at a glance, so size is the better check there. A full-grown guppy male still looks chunky next to an Endler.

Females are the problem. Both are plain silver-gray to gold with a dark gravid spot near the vent, and an Endler female is only somewhat smaller than a young guppy female. Shops often keep females of several livebearers in one tank. If you want pure Endlers, buy females from the same breeder as your males.

Why mixed tanks turn into hybrid tanks

Endlers and guppies cross freely, and the hybrids breed too. A guppy female will take an Endler male without hesitation, and the reverse also happens. Put both sexes of both species in one tank and the next few generations come out medium-sized with medium tails, which is what most "Endler guppy" shop tanks already hold.

That is the main reason to keep them apart. They don't fight, they share the same water, and the stocking calculator has no objection to them sharing a tank. If you want both in one tank without crossbreeding, keep one species as males only, or both as males only. Female livebearers store sperm, so a female from a mixed shop tank can still produce hybrid fry after she arrives. Quarantine new females alone for a month and you will usually see whether she was already carrying.

Hard water for both

Both fish come from hard, alkaline water and do best around 8 to 20 dGH with a pH of 7.0 or a little higher. Soft, acidic water set up for chili rasboras or cardinal tetras is a poor long-term home for either one. If your tap reads soft, the water hardness guide shows how to raise GH and KH with crushed coral or a mineral product. Raise it slowly, over several water changes.

Both want a heater in most homes. A tank set to 76°F suits either fish and also suits peppered or pygmy cories. Endlers handle the cooler end a little better, down to 72°F. Both jump, so fit a lid that covers the filter cutout.

Plans for a 10 and a 20-long

In a 10-gallon, Endlers are the better fit for a breeding group. Start with one male and three females on a sponge filter with plenty of plants, and expect the colony to grow. For no fry at all, ten Endler males in a planted 10 make a busy, colorful tank. For guppies, keep four or five males only. Mixed-sex guppies outgrow a 10 within a couple of months.

A 20-gallon long gives more choices. About a dozen Endlers with eight pygmy cories on fine sand fits. So do six male guppies with six peppered cories. Every plan in this section passes the stocking calculator at its tank size with room left over. Fry are the part the calculator can't see, so recount every few months and rehome extras.

Cherry shrimp adults do fine with Endlers, which have small mouths. Shrimplets still get eaten, so a shrimp colony will grow slower than it would on its own. Big guppy females eat more shrimplets than Endlers do.

Fry and how fast a tank fills up

Guppies have bigger broods. A mature guppy female often drops 20 to 50 fry about every four weeks. Endler females drop smaller broods, usually 5 to 25, a little more often. Either way, a few females in a planted tank can double your fish count in a couple of months.

Plants like java moss and floating plants give fry cover. Most adult livebearers eat newborn fry, so a bare tank stays steadier and a jungle fills up. Endler fry are tiny and easy to miss until they color up. If you don't want any fry, keep males only and buy them already sexed, which with Endlers is usually easy after about six weeks of age.