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Issue: May 2013

7 Forgotten Livebearers (Full Article)

Author: Neale Monks, PhD

MONKS T 0811
Photographer: Neale Monks, PhD
Generally hardy with interesting colors and behaviors, wild livebearers make excellent fish for beginning to advanced aquarists.





There’s not much to be cheerful about with the way the current economy is, but something that might help is to learn how to appreciate the simpler things in life. As much fun as reef tanks and high-tech planted aquaria might be, they’re expensive to build and maintain. But a 10- to 20-gallon tank stocked with livebearers and a few floating plants? Easy as pie! Plus, happy livebearers are busy livebearers, which means you’ll soon end up with surplus fish you can trade in at your local pet store or auction at fish clubs. What could be better than an interesting aquarium that can help pay for itself?

You might be wondering what livebearers have been forgotten. If you look at aquarium books from the first half of the last century, you’ll often find dozens of livebearers species that are hardly ever included in modern books. I’ve got a copy of the ninth edition of Exotic Aquarium Fishes by William Innes (Innes Publishing Company, 1948) next to me here, and the livebearer section is a revelation, with 26 different livebearer species listed! Compare that to the average modern aquarium book, which likely list only guppies, mollies, platies, and swordtails.

If aquarists 60 years ago kept many different livebearers, why do we only keep the big four species today? The simple fact is that the four most common livebearers are the ones that have been bred into the variety of colors many hobbyists seem to prefer. But that has been achieved at a cost, and fancy livebearers are demonstrably less hardy than their wild forebears. Furthermore, as wild-type livebearers slipped from the hobby, advanced aquarists gradually came to view livebearers as fish fit only for the most casual hobbyists, and not nearly as worthwhile as, say, catfish or cichlids.

Let’s look back at some of the fish Innes knew and loved. Oddball fish don’t have to be vicious predators, and breeding projects don’t have to be herculean tasks involving complex water chemistry management and the production of live foods. Advanced hobbyists can rediscover some old friends, and beginners will learn why livebearers were once lauded as the toughest of the tough. Ladies and gentlemen, it’s time to fall in love with the livebearers again!

Metallic Girardinus Girardinus metallicus

As their name suggests, both sexes of Girardinus metallicus are metallic fish. Their colors range from silver to gold depending on the lighting, and there is a hint of vertical banding on the flanks. Males also bear black blotches that cover their heads, throats, and anal fins, though the amount of black varies from fish to fish. As is often the case with livebearers, females are larger than the males. The females get to almost 3 inches, while the males grow to about 1½ inch.

Metallic girardinus are charming fish that make wonderful additions to densely planted aquaria from 10 gallons upward. They aren’t fussy fish, and while they may prefer slightly brackish conditions in the wild, they will do perfectly well in moderately hard, basic freshwater conditions. Given their size, companions should be chosen with care. Cherry shrimps and nerite snails, or Corydoras and the smaller barb, tetra, and rainbowfish species would be suitable.

If you’ve bred any of the “Big Four” livebearers, what you know will apply to these other species. Be sure to start with more females than males, as amorous males can harass pregnant females, and that’ll lead to miscarriages. Next, add a few clumps of floating plants, Ceratopteris thalictroides being ideal. These plants will provide hiding places for both females and their fry. While metallic girardinus are not especially cannibalistic toward their fry, it can happen. With the plants in place, it’s easy to look over the plants each morning and net out any fry for rearing in a large breeding trap until they’re big enough to set loose again.

Dwarf Mosquitofish Heterandria formosa

The dwarf mosquitofish is unusual in that males and females look quite similar. Both are silvery and feature a black band running along the midline of the body. Both sexes also possess a black spot at the base of their dorsal fins. To sex these fish, the aquarist needs to look at their anal fins. On males, this is a long tube-like structure, whereas females have a triangular anal fin much like that of any other fish. Like all other male livebearers, males use their anal fin to direct sperm into the females when mating.

These are tiny fish! Males are barely ¾ inch in length, and females reach less than 1½ inch. While they’re very peaceful, their small size means that they really shouldn’t be kept with any other fish. If you must choose tankmates, try cherry shrimps or bumblebee shrimps, as these will thrive in the same cool, hard, basic water that the dwarf mosquitofish require. The addition of marine salt mix at ½ to ¾ ounce per gallon will create slightly brackish conditions appreciated by these fish. Salt is useful against white spot and velvet, but it isn’t essential by any means.

Unlike most other livebearers, this species is a subtropical fish that needs to be kept at around 64˚F, perhaps a bit cooler in winter and a little warmer in summer. It despises strong water currents and open spaces, but an 8-gallon tank stocked with floating plants and an air-powered sponge or box filter will suit it perfectly. Like other livebearers, the dwarf mosquitofish does well on a mixed diet that includes algae-based flakes alongside small invertebrates, such as brine shrimp and daphnia.

Humpbacked Limia Limia nigrofasciata

If the two previous livebearers are understated gems, the humpbacked limia is a brassier fellow altogether! Not only are both sexes glittery, translucent, and honey-yellow in color, the male tops that off with an attractive sailfin marked with purple flecks. As the males mature, they become distinctly humpbacked in shape, hence their common name.

Humpbacked limia Limia nigrofasciata aren’t hard to keep, as they are similar to platies in size and temperament, though they are happier in slightly warmer water. Temperatures ranging from 72˚ to 82˚F suit them just fine. Like platies, they prefer gentle water currents. Water chemistry isn’t critical, though hard or slightly brackish water is best. They thrive on algae-based flake food with occasional offerings of bloodworms and brine shrimp. Males are a little feisty, but this species is highly social, perhaps more so than the average livebearer. It’s worth starting with at least six, two males and four females, in an aquarium from 15 gallons upward. Floating plants are a major plus, providing both shelter for the somewhat nervous adults as well as hiding places for the fry.

Black-Bellied Limia L. melanogaster

L. melanogaster is also sometimes traded. This species is highly variable. Females are essentially greenish-gray with neon-blue scales along the bottom half of their bodies, and males are similar but smaller and tend to have some black and sulfur-yellow patches on their heads, flanks, and fins. Again, overall size and temperament is comparable to that of platies. Males measure a bit under 2 inches when fully grown, females a trifle more.

Breeding is straightforward and similar to breeding guppies or mollies. Indeed, Limia species will readily hybridize not only with each other but with Poecilia species as well. As a general rule, it’s best to keep just one livebearer species per tank unless you know for sure they won’t hybridize.

Liberty Molly Poecilia salvatoris

Although Innes included the liberty molly in Exotic Aquarium Fishes, most subsequent writers have regarded it as a mere variety of Poecilia sphenops, the common molly. Only recently has the liberty molly been recognized as something distinct, and this very pretty livebearer is now increasingly regularly traded.

This species has very lovely colors. Both sexes are silvery white with orange and blue speckles, but while the females have rather weak colors on their fins, the males have fins that are boldly marked with black, neon blue, and either burgundy or yellow depending on the morph. The burgundy one is most often traded, and the combination of red, white, and blue is presumably where the liberty molly name comes from. Coloration improves with age, and older, dominant males have large, almost sail-like dorsal fins and intense coloration.

But while the small livebearers mentioned so far have been more or less peaceful, community-safe fish, the liberty molly can be very nippy and aggressive. Actually, most other kinds of mollies can be quite nasty toward their tankmates as well, something beginners often learn the hard way. While liberty mollies are supremely attractive fish in many ways, they aren’t for everyone, and they’re definitely best kept alone in a tank of their own.

Males will fight relentlessly in small tanks, and if there are only two males in the group, the weaker one will likely be bullied to death. Keep liberty mollies in groups where females outnumber males two to one, and keep either just a single male or at least three.

As with all mollies, this species is primarily herbivorous and does well on algae-based flake food. Their maximum length is about 3 inches, with males being generally smaller than females. A 30-gallon tank should be adequate for a group of three males and six females. Like most other mollies, this species is jumpy and shouldn’t be kept in an open-top aquarium.

Wrestling Halfbeak Dermogenys spp.

Innes tagged the wrestling halfbeak onto the end of his livebearer section, and almost all aquarium writers have since followed suit. That’s a shame because halfbeaks are among the most entertaining small fish, with their odd body shape, bright colors, and lively personalities. True, some are quite delicate, but wrestling halfbeaks are not fussy fish once settled into the aquarium. Water chemistry can be either hard or brackish, and water temperature can be anything from 68˚ to 86˚F.

The genus Dermogenys contains a dozen or so very similar species. Most of the wrestling halfbeaks in the trade are called D. pusilla, but really, it’s anyone’s guess what they really are. Females get to about 2 to 3 inches in length, males rarely more than 2. Body color varies from silvery white to greenish gray, and apart from differences in size, the males can also be distinguished by the patches of red, yellow, and black visible on their fins. There’s a lot of variation, though, and some are much more colorful than others.

Basic care seems to be consistent. Males are aggressive toward one another, but they will generally avoid each other if provided adequate space. A 20-gallon tank will be enough for three males and six females. Halfbeaks need a varied diet that includes some live or frozen foods alongside the usual dried and flake foods. Halfbeaks were often described as poor community fish in the past, but that isn’t really fair. True, they won’t compete with aggressive fish at feeding time, but they are easily kept with slow-moving or bottom-feeding fish such as Corydoras, kuhli loaches, or bumblebee gobies. Halfbeaks are also very jumpy, so don’t keep them in an open-top tank!

Breeding is basically similar to that of other livebearers, with females producing batches of fry four to six weeks after mating. The fry are quite large, however (½ inch or so), and will take finely powdered flake food alongside brine shrimp nauplii, microworms, and even small daphnia. But for whatever reason, wrestling halfbeaks are prone to fertility problems as they age. Many aquarists have noticed that while their halfbeaks initially produced quite large broods of 20 or more fry, successive broods are smaller and miscarriages are more common. Some fishkeepers think diet is to blame, while others say water chemistry. The reality is that nobody knows, and the best approach is to set up a colony of halfbeaks so there are always some young, fertile fish in the group.

One That Got Away: Ameca splendens

Although Innes didn’t include the butterfly goodeid Ameca splendens, it’s worth adding here because it’s such a wonderful—if exasperating—livebearer. Why exasperating? Well, few fish can rival this one as a fin nipper. Besides going for the usual slow-moving and long-finned species, it’ll even peck away at Corydoras catfish! While the butterfly goodeid can be kept in a mixed-species setup, any companions need to be fast moving and at least as boisterous. Tiger barbs and skunk loaches are two possibilities. In addition to being nippy, males are very aggressive toward one another. Curiously, this seems to be a trait peculiar to captive-bred specimens; wild-caught species and their immediate descendants are far less aggressive.

But if the butterfly goodeid is such a thug—and it is!—why keep it at all? Simple. It’s a beautiful, fun, and interesting fish. Females are merely silver with black speckles, but mature males acquire turquoise-blue metallic scales on their flanks and bright yellow banding down the edge of their tail fins. Their colors vary with status, and the dominant male has very intense coloration. In common with other goodeids, females produce small batches of large offspring, around 20 being typical, with each newborn being up to 4/5 inch in length. To put that in perspective, a newborn butterfly goodeid isn’t much smaller than the young neon tetras seen in pet stores! Adults generally ignore their offspring, and in tanks with floating plants, they can be left to grow up with their parents.

Basic care is straightforward. Butterfly goodeids appreciate tanks from 30 gallons upward with a brisk current with hard, alkaline water that isn’t too warm. Temperatures in the 64˚ to 75˚F range are ideal. Large groups work best, with females outnumbering males two to one and at least four males being required to avoid problems with bullying. Algae-based flake food is a good staple, but fresh greens like floating Indian fern and duckweed will give these greedy fish something to graze on between meals.

Oddly enough for such prolific, easily pleased little fish, butterfly goodeids are nearly extinct in the wild. It isn’t often that hobbyists can say they’re doing something to help secure the future of a species, but in the case of those keeping the butterfly goodeid, they most definitely are.

Livebearers for All Levels

Though this is just a short review of a few of Innes’ wild livebearer species that are not commonly kept today, it’s easy to see that livebearers are hardy, colorful, and full of personality. Whether you’re a beginner looking for a pretty, hardy species or an advanced aquarist looking to preserve an endangered one, there is a wild livebearer that is right for you.

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