Porthole livebearer

Poeciliopsis gracilis

FreshwaterFish

Care at a glance

Temperature: 72–82°F (22–28°C)
pH: 6.5–7.8
Adult size: 3.5 in (9 cm)
Minimum tank: 11 gal (40 L)
Temperament: Peaceful
Social behavior: Social
Swim level: Middle
Difficulty: Beginner
Breeding: Easy
Rarity: Common
Origin: Central America; Atlantic slope from southern Mexico to Honduras
Family: Poeciliidae

Overview

Keep them as a small colony with more females than males, in a tank of 40 liters or larger, since males chase persistently and extra females spread out the attention. They are peaceful mid-water swimmers that hold up well across roughly 22 to 28 C and a pH of 6.5 to 7.8, and they take hard water without trouble. Feed prepared flake, which they eat readily, and supplement with live or frozen foods like baby brine shrimp and microworms. They are extremely prolific, dropping 6 to 15 fry per brood every few weeks, so plan ahead for population control or rehoming. Never release unwanted fish or fry into local waters, and check your local rules, since hardy livebearers can become invasive in warm regions.

In the wild

Porthole livebearers come from streams and ponds on the Atlantic slope of Central America, from southern Mexico down through Honduras. These are warm, often hard-water habitats, and the fish handle a wide range without fuss. Give them a tank of at least 40 liters with some planting and open mid-water space to swim. Keep the water between 22 and 28 C with a pH from 6.5 to 7.8, and put a tight lid on the tank since they jump.

Good to know

This is a livebearer in the family Poeciliidae, with a reported maximum length around 9 cm. Females noticeably outgrow males, often reaching 6 to 7 cm while males stay smaller. Like other poeciliids, females give birth to live, free-swimming fry rather than scattering eggs, and they can carry brood after brood every few weeks.

Did you know

Females do most of the growing in this species, ending up well larger than the males, which top out around 6 to 7 cm. A single female can stay productive for a long stretch, turning out a fresh batch of fully formed fry every few weeks, which is why a small group can fill a tank surprisingly fast.