TankBud

Dusky millions fish

Phalloceros caudimaculatus

Also known as Caudo, Speckled livebearer

FreshwaterFish

Dusky millions fish (Phalloceros caudimaculatus)
no rights reserved, uploaded by demianlescano · cc0

Care at a glance

Temperature
64–75°F
18–24°C
pH
7.0–8.0
Adult size
2.4 in
6 cm
Minimum tank
12 gal
45 L
Temperament
Peaceful
Social behavior
Social
Swim level
Middle
Difficulty
Medium
Breeding
Livebearer · Easy
Rarity
Common
Family
Poeciliidae
Origin
South America: coastal Brazil (Rio de Janeiro southward) through Uruguay, Paraguay, and northern Argentina

Overview

The dusky millions fish is a hardy, peaceful livebearer for a cool, planted tank. It suits a keeper with a little experience.

Did you know

The dusky millions fish takes its common name from how freely it breeds. One well-fed group in a planted tank can soon become a crowd, as females drop batch after batch of live young. The fry survive well among dense plants, and that same hardiness has spread the species far outside its native range.

Caring for the dusky millions fish

Keep dusky millions fish in a group of at least six in 12 gal (45 L) or larger. Give them a heavily planted tank with gentle filtration and modest flow, and the dense plants will give the fry somewhere to hide. They spend most of their time in the middle of the tank.

Keep them on the cool side, at 64 to 75°F (18 to 24°C). They tolerate unheated rooms and brief cold spells far better than long stretches of warm water. The water should be neutral to slightly alkaline and moderately hard, with a pH of 7.0 to 8.0. They dislike sudden shifts in water chemistry, so do small, frequent water changes.

Feed flakes, small pellets and frozen foods such as daphnia. Dusky millions fish are peaceful, so pick non-nippy tank mates that also handle cool water. Skew the ratio to two or three females per male, so no single female takes constant attention.

Females reach about 6 cm, while males stay smaller at around 3.5 cm. Females give birth to live, free-swimming fry, and the species breeds readily without much help. Never release them, and check your local rules before keeping them, since they have become invasive in warmer regions.

Good to know

The dusky millions fish, Phalloceros caudimaculatus, is a livebearer in the family Poeciliidae, the same group as guppies and mollies. It also goes by the names caudo and speckled livebearer. A healthy fish can live several years.

In the wild

Dusky millions fish come from coastal South America, from Rio de Janeiro south through Uruguay, Paraguay and northern Argentina. Their range is subtropical.

Weekly picks

Tank mates

The dusky millions fish is a peaceful, social species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a dusky millions fish need?

A dusky millions fish needs at least 12 gal (45 L). It spends most of its time in the middle.

What temperature and pH does a dusky millions fish need?

A dusky millions fish is comfortable at 64–75°F (18–24°C) with a pH of 7.0–8.0.

What does a dusky millions fish eat?

A dusky millions fish eats flakes, small pellets and frozen foods such as daphnia.

How big does a dusky millions fish get?

An adult dusky millions fish reaches about 2.4 in (6 cm).

How can you tell a male dusky millions fish from a female?

Males stay small at around 3.5 cm, while females reach about 6 cm.

How does a dusky millions fish breed?

Dusky millions fish are livebearers, and the females give birth to live, free-swimming fry. They breed readily without much help.

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