TankBud

Rio pearlfish

Nematolebias whitei

Also known as White's pearlfish, Rio de Janeiro pearlfish, Cynolebias whitei

FreshwaterFish

Care at a glance

Temperature
68–77°F
20–25°C
pH
6.0–7.0
Adult size
3.1 in
8 cm
Minimum tank
14 gal
54 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 pools on the coastal floodplains around Rio de Janeiro in southeastern Brazil.

Overview

The Rio pearlfish is a seasonal killifish that stays near the bottom of a dim species tank. It is a fish for keepers with a little experience.

Did you know

The Rio pearlfish is a bi-annual killifish, because its home pools dry out and refill twice a year. Its eggs are set up to survive two separate dry spells, an unusual trick even among annual killifish.

Caring for the Rio pearlfish

Keep a male Rio pearlfish with two or three females in a species tank of at least 14 gal (54 L). Give them a dim tank with a deep soft substrate or a peat spawning tray, and fit a tight lid.

Hold the water at 68 to 77°F (20 to 25°C) with a pH of 6.0 to 7.0. Feed rich live and frozen foods such as bloodworm, blackworm, brine shrimp and daphnia to fuel their fast growth.

Rio pearlfish are mostly peaceful, but males display hard at each other. Give them plenty of room and cover, or keep a single male. Choose any tank mates with caution.

Males are stocky, with a blue-green body scattered with pearly white spots and red bars, while females are plain. Spawn them over a peat tray and store the eggs damp for a few months. In the wild the eggs enter diapause in the mud and hatch when the water returns. Breeding them is moderately difficult.

Good to know

The Rio pearlfish, Nematolebias whitei, is a killifish in the family Rivulidae. It is a hardy, prolific species, and it has become a model species for genome and developmental study.

In the wild

The Rio pearlfish lives on the coastal floodplains around Rio de Janeiro in southeastern Brazil. Its home is small, shallow freshwater pools over soft reddish mud.

Common questions

What size tank does a Rio pearlfish need?

A Rio pearlfish needs at least 14 gal (54 L). It spends most of its time in the bottom.

What temperature and pH does a Rio pearlfish need?

A Rio pearlfish is comfortable at 68–77°F (20–25°C) with a pH of 6.0–7.0.

What does a Rio pearlfish eat?

A Rio pearlfish eats rich live and frozen foods such as bloodworm, blackworm, brine shrimp and daphnia. These fuel its fast growth.

How big does a Rio pearlfish get?

An adult Rio pearlfish reaches about 3.1 in (8 cm).

How can you tell a male Rio pearlfish from a female?

Males are stocky, with a blue-green body scattered with pearly white spots and red bars. Females are plain.

How does a Rio pearlfish breed?

Rio pearlfish spawn over a peat tray. Store the eggs damp for a few months, since they rest in diapause until water returns. Breeding them is moderately difficult.

Related species