Not furry, but we like them anyway.

Merry Widow Livebearer

Phallichthys amates

Also called Merry widow

SpeciesShort profile

From Central America: Atlantic-side drainages from Guatemala (Motagua River) through Honduras to Costa Rica and western Panama.1 2

At a glance the quick version

Length3.2 to 7 cm2 1

Sizesmall

Hardy

Peaceful and outgoing

Easy to keep

Looks how to spot one

Deep-bodied scaled livebearer

A robust, deep, almost diamond-shaped body that is grey with bluish highlights. The dorsal fin is held upright, and males carry a very long gonopodium that reaches back to the tail.1 2

ColoursGrey with bluish sheenBlack stripe through the eye6-8 vertical barsBlack-edged dorsal fin (amates)Orange-red dorsal band (pittieri)2

Personality what they are like

A hardy, peaceful and outgoing fish that usually holds its dorsal fin proudly raised.2

Daily activity how busy a day looks

Moderate; lives near the bottom over soft ground in quiet water.1

Grooming and care the hands-on bits

Easy to keep; regular water changes and a diet with plant content suit it well.2 1

Home where they are happiest

Water about 24-27 °C (tolerates 20-37 °C), pH 6.0-8.0, moderately hard (9-19 dH). Wild fish live in still water, creeks and river edges over mud or leaf litter, so a soft substrate is a good match.1

Food basics what goes in the bowl

Grazes on detritus, diatoms and fine organic material, with some algae and aquatic insects. In aquaria offer a mix of plant-based and small meaty foods.1 2

Company who they like around

A peaceful community fish; keep with other calm species of similar size.2

The story where it all began

The species was described in 1907 and was once split into three species before being treated as one. The name 'merry widow' came from aquarist Frederick H. Stoye, who linked the fish's lively ways and black-edged dorsal fin to the operetta of that name.2

Fun facts for the dinner table

1
The genus name Phallichthys refers to the male's very long gonopodium.2
2
Young are born looking like small versions of the adults.2
3
Females produce about 10-80 young after roughly four weeks.1
4
The black dorsal edge was seen as 'mourning black', inspiring the 'widow' in its name.2

Recognised by the official bits

IUCN Red List: Least Concern (assessed 2019)1
Taxonomy: Family Poeciliidae; described in 1907; two subspecies recognised (amates and pittieri)2

The care rhythm Furry Diary remembers it for you

A typical home-care rhythm for a Merry Widow Livebearer. It is our own starting plan, not a vet's advice, and you can change every line in the app.

FeedingSmall amounts once or twice a dayevery day
Temperature checkevery day
Water changeAbout 25% of the waterevery week
Water testevery week
Glass cleanevery week
Filter rinseRinse in old tank water, never tap waterevery month

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Where this comes from

Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.

FishBase: Phallichthys amates fishbase.seused for origin, size, environment, diet, IUCN
Wikipedia: Phallichthys amates en.wikipedia.orgused for names, colour, behaviour, history, facts

Checked 2026-09-30. Text is written in our own words from these sources.