Meet the Merry Widows: The Genus Phallichthys

Author: Mike Hellweg

Though not as popular as staple livebearer species, the merry widows make great aquarium residents with their peaceful disposition, hardy nature, and prolific breeding habits.

Meet the Merry Widows

This is a great time to be a livebearer enthusiast. There are currently more than 150 species of livebearers circulating in the hobbyist community, plus more than a hundred color variants of the big four (guppies, mollies, swordtails, and platies). A visit to a local aquarium club meeting will often turn up more than a dozen species beyond the retail big four at just that one meeting. For example, in my local club (Missouri Aquarium Society, Inc.) over just the past year, we recorded 74 spawns from 49 species of livebearers in three families that were all submitted for our club’s Breeders Award Program (BAP). All of these were donated to our club and auctioned off as a fundraiser during our regular monthly meetings. This helps spread them around to other hobbyists. Many other clubs do this same thing.


Attending a local, regional, or national organization’s annual auction might turn up even more. The upcoming American Livebearer Association’s famous Sunday auction will present more than 500 lots for sale—all livebearers, including some old favorites and some new species! Add in the availability of livebearers on the Internet (even in the depths of winter), and you’ll see what I mean. For example, a quick look on a popular fish auction site shows more than a dozen sellers listing nearly 40 species of wild-type livebearers, plus nearly 20 sellers with dozens of fancy livebearer types.

Among the wild-type livebearers currently circulating are the four known members of the genus Phallichthys, more commonly known as the merry widows after their best-known species. In fact, at two recent auctions I attended, all four known species from the genus were available.

Fascinating Gonopodium

“Merry widow” seems like a strange name for a fish, but it’s much better than a literal translation of its generic name “phallus fish,” which refers to the male’s oversized gonopodium. This is one of the most striking things about the fish, so striking that Carl Hubbs based the group’s generic name, Phallichthys, on this structure. The gonopodium is the name given to the male’s modified anal fin that serves to deliver sperm packets, called spermatophores, into the female’s genital pore. The gonopodium of Phallichthys is comparatively huge. It begins almost directly below the first ray of the dorsal fin and ends in an enlarged hook right near the beginning of the caudal fin. In a 1-inch male, it can be nearly ½ inch long!

Where Did That Name Come From?

The name merry widow is credited to the well-known early 20th century hobbyist Frederick H. Stoye, a friend and employee of aquarium hobby pioneer William T. Innes. Mr. Stoye, a German immigrant to the United States, was an aquarium hobbyist who worked and wrote extensively in both Germany and the US. His book, Tropical Fishes for the Home: Their Care and Propagation, was one of the first bestsellers published on breeding fishes. By the early 1930s, he had become the associate editor of Innes’ flagship magazine, The Aquarium. While there are lots of strange stories surrounding the origin of the name, Innes records the true beginnings in his masterwork Exotic Aquarium Fishes, where he remarks that Stoye gave the appellation to P. amates due to their “lively habits, plus the mourning [black] edge on the dorsal fin.” It was customary during that period for those in mourning to wear black. In addition, there was a popular opera at the time called the merry widow, which may have further sparked his imagination.

Native Habitat

In the wild, the four species are found along the Atlantic slope from Guatemala in the north to Panama in the south. This is a good general description of their distribution, but I should point out that at least one population is reported in extreme southern Mexico and a few specimens are reported from Pacific drainages in the southern end of their distribution, but it’s unclear in the literature whether this is a wild distribution or these are introduced populations. P. amates is the most widespread, being reported from southern Mexico all the way to Panama. In fact, at one point it was considered three separate species—P. amates from the Rio Montagua in Guatemala, P. pittieri from the Rio Reventazon in Costa Rica, and P. isthmensis from Colon in Panama. Almost immediately it was recognized that P. pittieri and P. isthmensis were the same species. All were later made synonyms of P. amates.

Two subspecies are recognized by most authors today—P. amates amates with a black band along the edge of the dorsal fin, and P. amates pittieri with an orange or red-orange dorsal band along the dorsal edge with a charcoal-colored band inside that orange band. While fairly widely available in the 1980s and early 1990s, I have not seen fish matching the description of P. amates pittieri since then.

In 1959, Rosen and Bailey added P. fairweatheri from the Rio Usumacinta Basin in Guatemala to the genus. P. tico, from the Rio Sarapiqui drainage in Costa Rica, was added by Bussing in 1963. Most recently, in 1979, Bussing added P. quadripunctatus from the Rio Sixaola in Costa Rica to the genus. As there are numerous river systems separating the known species, it is possible that ranges may be extended or even new species discovered as further research is done in years to come.

Aquarium Husbandry

All of the merry widows are great community fish that even beginning hobbyists can easily maintain. In fact, the merry widow may be a better first livebearer than even the guppy. They are hardy, outgoing, and, if fish can be so, personable. They are clearly aware of what is going on around their home tank and will beg for food from their owner, while often ignoring other humans that approach the tank.

While they are always out on display, they are not aggressive.


I have kept the various species in colony tanks without any other species, with various catfish (cories, bushynose plecos), with other livebearers (as their reproductive structures are very different from other poeciliids, there is little chance of accidental crossbreeding with any livebearers other than other Phallichthys species), with smaller Central American cichlids such as Honduran red pointsand various Thorichthys species, as well as with rainbowfish, tetras, barbs, and even gouramis. Keep in mind that when sharing a tank with most of these species, merry widows are unlikely to have any fry survive more than a few days, as the other inhabitants will consider them a snack.

Aquarium Requirements

They are most often found in slow-flowing streams, creeks, and other backwater to stagnant areas, usually over a mud bottom. They are often found in association with aquatic plants. This adaptation to slow-flowing shallow water makes them ideal candidates for the aquarium. They seem to do especially well in planted tanks, where multiple generations can grow up in a large colony. I usually keep them in multigenerational groups in medium-sized tanks—20 to 55 gallons in size. I add Java moss and Java fern attached to rocks, and floating plants like Najas spp. or hornwort. Most of the time, they are the only species in the tank other than Ancistrus or Corydoras species. I also have ramshorn snails and small shrimp in most of my tanks.


In the wild, they are mostly reported to graze on algae and microfauna growing on every surface in the stream, as well as the occasional insect and crustacean. In our aquaria, they are not fussy eaters and will consume high-quality flake, pellet, frozen, freeze-dried, and live foods. They will also be seen nibbling on every surface in the tank, likely consuming the biofilm between meals.

Water Parameters

Water parameters are not too important. My colonies have done well in our local tap water with a pH around 7, a total hardness of 125 ppm (GH 7), and carbonate hardness that fluctuates throughout the year but usually remains around 60 ppm (KH 2). In the spring, I usually add a liquid buffer that is designed to add minerals to the water, and I have crushed coral in most of my Central American tanks too. If the snails start showing pitting on their shells, I know the carbonate hardness has dropped too low and I do a water change and add the liquid supplement.

Water changes are important to keep down dissolved organics, and I do 50 percent changes every week. Some populations of merry widows are found at higher elevations and can tolerate cooler water, so I don’t bother with a heater. Room temperature in my fishroom never drops below 72°, and they seem to be happy.


As with most of the poeciliids, the members of the genus Phallichthys all give birth to living young capable of surviving on their own from birth, and after birth neither parent provides any care to the young. They also usually ignore the young, so there is no need to remove or separate the fry from the adults. Fry are colored exactly as their parents right from birth, right down to the black-lined dorsal of P. amates and the four black spots of P. quadripunctatus. Gestation usually lasts around four weeks, though at warmer temperatures (over 80°) this can take just over three weeks.


I have not seen the males perform any complicated mating dance, and while mating does require the cooperation of the female, the male completes the act with an approach from below and behind the female with the gonopodium extended in front of his head. The hooked end may help him hold on during copulation.

Young females grow and mature quickly and can give birth to their first litter when they are just about an inch long. The first drop may be only three or four fry, but as they grow, these batches may grow to as large as several dozen in P. amates. In the other species, drops usually average around 30 or even less.


Newborn fry head for cover and can be found all over the tank from the substrate to the surface. They are ravenous eaters and grow quickly. I feed them the same foods as the adults, plus an additional feeding of newly hatched brine shrimp every day. In just over seven weeks, the young males will start to develop their gonopodia. By 10 to 12 weeks, the young females are likely already carrying their first brood.

Meet the Species

Merry Widow (Phallichthys amates amates)

The merry widow (P. amates amates) is the largest species in the genus. It is high bodied with a pointed head and has a solid look to it. Females grow to almost twice the size of the males and can reach 2½ inches to the males’ 1¼ inches. Depending on the light, they have a pale gray/gold body that has a bluish metallic sheen in reflected light. There is a black stripe through the eye that runs to the throat. Their most stunning feature is the black stripe along the edge of the dorsal fin, which is sometimes edged in a thin white stripe. In some populations, faint banding can be seen running along the sides, and sometimes the scales are edged in a reticulated pattern. Other specimens can be very pale by comparison. The dorsal is always carried erect in both sexes. Large females have been reported to drop as many as 60 or even more fry.

Orange-Fin Merry Widow (P. amates pittieri)

The orange-fin merry widow (P. amates pittieri) is just a bit smaller and more gracile than P. a. amates and is reported to grow to about ¼ inch or so less than its congeners. They tend to have a more grayish body with a blue metallic sheen. The scales are usually outlined in a reticulated pattern. Many specimens have a few wide bands along their flanks. As noted earlier, their dorsal is edged in an orange band with a charcoal color below it.

Banded Merry Widow (P. fairweatheri)

The banded merry widow or picotee livebearer (P. fairweatheri) is a smaller species, with males topping out at around an inch, and females about 1½ inches. The body is gray with blue overtones and covered with rows of orange spots running horizontally. The back half of the male’s body is a warm amber color, usually with four wide, dark bands on the amber background. The fins are pale yellow. The dorsal fin has a black edge, though it is not as striking as in P. a. amates. Broods usually number in the 20s, though batches of three dozen are not unheard of.

Dwarf Merry Widow (P. tico)

The dwarf merry widow (P. tico) is a small species. Males rarely reach an inch and are usually much smaller. Females usually don’t reach 1¼ inches. They are more elongate than the other species, and even though the male’s gonopodium is actually no larger than in the other species, it’s even more striking due to the smaller body size. They seem to do better in warmer water around 80°. Broods are usually fairly small—a dozen is a good-sized drop.

The females I’ve kept perform an unusual maneuver as they reach sexual maturity. Anyone who has kept fish for any length of time has seen the “spiral of death” when a fish begins doing a quick, wide roll in the water column. Usually that particular fish is dead a short time later. Well, every single female P. tico I have had in my colony performed that same maneuver! Each one did this individually, while all of the other fish in the tank were fine. The first time I noticed it, I thought something was wrong. I immediately did a large water change and hoped for the best. Over the next few days, I noted that other young females were doing the same thing, and the ones that had done it earlier were just fine. After observing this several times over several years, I concluded that, at least in my line of fish, young females did this around the time they reached sexual maturity. It was never repeated in their lifetimes, at least not that I ever observed. I’m not sure what caused them to do this, if it’s normal for the species, or why they did it. But every single one of my fish did it.

The Four-Spot Merry Widow (P. quadripunctatus)

The four-spot merry widow (P. quadripunctatus) is another small merry widow. Males reach about ¾ inches, and a really big female might reach 1½ inches. They are a bit more elongate in body shape than P. a. amates, and the gonopodium is not as long as in the other species, usually falling far short of the caudal fin. Their dorsal fin is a pale blue with a black edge, and females often have a blue anal fin. The rest of the fins are clear, and they have a yellowish tinge on the body. But what really stand out are the four black dots on the body. The first two are above the lateral line while the back two are on the line. The first one is on the back halfway between the eye and the beginning of the dorsal fin. The second is at the base of the front of the dorsal fin. The third is behind the dorsal fin, and the final spot is at the base of the caudal fin on the caudal peduncle. These spots are there from birth. It’s really cool to see the little ¼-inch-long newborns swimming around right after birth with a colorful dorsal and four spots, just like their parents.

Be Merry with Merry Widows

The merry widows live up to their namesake. They are lively, attractive without being ostentatious, and easy to care for. They breed readily and are in demand with other hobbyists. What more could a livebearer enthusiast want?