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
- Difficulty
- Medium
- Breeding
- Medium
- Rarity
- Rare
- Family
- Rivulidae
- Origin
- Native to shallow seasonal pools on the coastal floodplains around Rio de Janeiro in southeastern Brazil.
Overview
Keep a male with two or three females in a 54 litre species tank at 20 to 25 C and pH 6.0 to 7.0. Males display hard at each other, so give plenty of room and cover or keep a single male. Feed rich live and frozen foods such as bloodworm, blackworm, brine shrimp, and daphnia to fuel their fast growth. Spawn them over a peat tray and store the eggs damp for a few months.
In the wild
It lives in small, shallow freshwater pools over soft reddish mud that dry out twice a year on the Rio de Janeiro lowlands. Males are stocky with a blue-green body scattered with pearly white spots and red bars, while females are plain. A dim tank with a deep soft substrate or a peat spawning tray and a tight lid suits it.
Good to know
Nematolebias whitei is unusual in being a twice-yearly, or bi-annual, killifish because its pools dry and refill two times each year rather than once. Its eggs enter diapause in the mud and hatch when the water returns. It is a hardy, prolific species that has become a genome and developmental study model.
Did you know
Because its home pools dry out twice in a year, its eggs are set up to survive two separate dry spells, an unusual trick even among annual killifish.
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.
How big does a Rio pearlfish get?
An adult Rio pearlfish reaches about 3.1 in (8 cm).
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