TankBud

Fighting gaucho

Cynopoecilus melanotaenia

Also known as Fighting gaucho killifish, Melanotaenia killi

FreshwaterFish

Fighting gaucho (Cynopoecilus melanotaenia)
W.S.Serra · CC BY-SA 4.0

Care at a glance

Temperature
64–75°F
18–24°C
pH
6.0–7.0
Adult size
1.8 in
4.5 cm
Minimum tank
5 gal
20 L
Temperament
Mostly peaceful
Social behavior
Social
Tankmates
With caution
Swim level
Bottom
Diet
Carnivore
Difficulty
Medium
Breeding
Egg burier · Medium
Rarity
Rare
Family
Rivulidae
Origin
Native to shallow seasonal swamps and grassy pools of the coastal lowlands of Rio Grande do Sul in southern Brazil and neighbouring northeastern Uruguay.

Overview

The fighting gaucho is a tiny annual killifish for a small, planted species tank. It is best with a little experience.

Did you know

The male fighting gaucho fertilizes the female internally before she lays her eggs. Almost all other killifish fertilize their eggs in the water. Among killifish, only its close relative Campellolebias shares the trait.

Caring for the fighting gaucho

The fighting gaucho is small and fairly gentle. A pair or trio is comfortable in a species tank of at least 5 gal (20 L). Plant it densely, and give them dim light and a soft bottom. The tank should stay cool and shaded.

Hold the water at 64 to 75°F (18 to 24°C), with a pH of 6.0 to 7.0. Feed small live and frozen foods such as daphnia, micro worm, baby brine shrimp and finely chopped bloodworm. Do not mix fighting gauchos with boisterous fish, and choose any tank mates with caution.

Males are slender, with a dark side stripe and red and blue markings in the fins. In the wild the eggs survive the dry season buried in the substrate. In the tank, spawn a pair over peat and store the eggs damp for a couple of months. Breeding them is moderately difficult.

Good to know

The fighting gaucho, Cynopoecilus melanotaenia, is a killifish in the family Rivulidae. It is the type species of its genus, and part of a complex of very similar killifish from southern Brazil.

In the wild

The fighting gaucho lives on the coastal lowlands of Rio Grande do Sul in southern Brazil and in neighboring northeastern Uruguay. Its home is shallow seasonal swamps, temporary marshes and grassy pools that dry out each year in a subtropical climate.

Common questions

What size tank does a fighting gaucho need?

A fighting gaucho needs at least 5 gal (20 L). It spends most of its time in the bottom.

What temperature and pH does a fighting gaucho need?

A fighting gaucho is comfortable at 64–75°F (18–24°C) with a pH of 6.0–7.0.

What does a fighting gaucho eat?

A fighting gaucho eats small live and frozen foods. Offer daphnia, micro worm, baby brine shrimp and finely chopped bloodworm.

How big does a fighting gaucho get?

An adult fighting gaucho reaches about 1.8 in (4.5 cm).

How can you tell a male fighting gaucho from a female?

Males are slender, with a dark stripe along the side and red and blue markings in the fins.

How does a fighting gaucho breed?

Fighting gauchos lay eggs that survive the dry season buried in the bottom. Spawn a pair over peat, then keep the eggs damp for a couple of months. Breeding them is moderately difficult.

Related species