San Marcos goodeid

Care at a glance

Overview

This is a hardy, active livebearer that lives in the middle water and does best as a colony, so keep a group with a good share of females to spread out the males' attention. It is generally peaceful, but males can be nippy and pushy, so treat tankmates with caution and either keep it in a species tank or pick robust companions with short fins. It grazes plant matter in the wild, so include vegetable and spirulina foods alongside regular flake and small frozen items. It likes clean, moving water and does not need heat. A tank of around 75 liters or more suits a colony.

In the wild

The San Marcos goodeid comes from a small spring-fed system in Jalisco, Mexico, in cool, hard, moving water. Recreate that with good current and filtration, moderately hard and alkaline water, and a stable temperature on the cooler side, from 18 to 26 C at a pH of 7.0 to 8.2. It does not want tropical warmth, and generous water changes keep it in condition.

Good to know

Xenotoca doadrioi is a splitfin in the family Goodeidae, reaching about 5 centimeters, the males slate-bodied with an orange tail band. It was split from Xenotoca eiseni as its own species in 2016 and is now critically endangered in its shrinking Jalisco springs. Breeding is of moderate difficulty: a livebearer with a gestation of roughly seven to eight weeks that gives birth to a modest brood of well-developed young.

Did you know

Goodeids nourish their unborn young through trophotaeniae, ribbon-like cords that work like a placenta and trail from the belly at birth. It is a mammal-style connection built independently by a small Mexican fish.

Common questions

Related species

• 

  Redtail splitfin

  Xenotoca eiseni

  Freshwater

  2.8 in (7 cm)20 gal (75 L)64–82°F (18–28°C)
• Jeweled splitfin

  Xenotoca variata

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• 

  Relict splitfin

  Xenoophorus captivus

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• Golden skiffia

  Skiffia francesae

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• 

  Rainbow goodeid

  Characodon lateralis

  Freshwater

  2.4 in (6 cm)15 gal (57 L)61–75°F (16–24°C)

• 

  Spotted skiffia

  Skiffia multipunctata

  Freshwater

  2.4 in (6 cm)16 gal (60 L)68–79°F (20–26°C)