View Full Version : Killifish: A Primer

10-08-2010, 08:18 AM
Though uncommon in shops, killifish have been in the hobby longer than almost any fish one could think of. Sailors brought back killies from distant ports as early as the mid 19th century, trading the glittering little fish for necessities, with the first international killies kept in the US arriving just after the first world war. Most killies available are native to West Africa and the United States, with a handful from Southeast Asia and South America.

And glittering they are. Some are so brilliant to put marine fish to shame. And though they range in size from a bit over an inch to nearly six inches, killies, given proper environs and foods, can be easily kept. But the potential keeper must keep the killie tank tightly covered, since many of these fish jump, some of the larger species over 12 inches above the water level.

In this primer we'll cover several species and their care. There are but a few tenets before one delves into killie keeping; though a few are common, finding a quality source for them can be a challenge, most will only take live foods initially, and many must be kept in a tank by themselves.

But, killie keeping is a deeply rewarding experience, as generations of killies can be raised by a keeper. And there's also a thriving national organization: The American Killifish Association, in which members can trade fish, eggs, the latter even internationally. Much knowledge can be gained in the art of killie keeping, and the annual AKA national convention is not to be missed.

There are two types of killies available - annuals and perennials. Annuals evolved in pools that dry up in the dry season, thus they grow fast, lay their drought resistant eggs, and the adults die as the pools evaporate. Though annuals don't necessarily live just a year, a keeper is both fortunate and skilled to keep them past two years. Most aren't really tropical, so 72 to 76 would be the proper temps.

Perennials can live quite some time, many easily five years, some of the larger species as many as eight or nine. In this list we'll start with the perennials.


Native to the southeast corner of the US is the Florida Flag Fish; Jordanella floridae.

Male Flag Fish reach 2.5 inches and possess the majority of the colors, like nearly all killifish do. Native to Floridian swamps, males sport a metallic, silvery body, moving toward a blueish top. Red stripes along the fish with the blue give it its common name. The unpaired fins are greenish to blue green and marked with red striping. She is a little smaller, her silver is greenish, stripes are dark and unpaired fins sport an orange cast near their bases. Her dorsal has a dark spot below it, and more dark spots are usually scattered about her. Both sexes can change colors at will, so she can be barred occasionally with varying levels of green and silver, and he can look uncannily like an American flag when at his best when morning sun hits the tank,

In feeding, Flag Fish MUST have real, green algae in their diet, and they'll make short work of any algae that may crop up. Given the algae, Flag Fish are quite hardy, and will happily take live, and eventually even frozen, foods. It isn't uncommon for Florida Flag fish to live five years and more. This is one fish that should be moved to a species tank, as the male is too combative toward his mate and tankmates when spawning, for the community aquarium. Though Flag Fish are killies, or more properly, American pupfish, the males behave almost Cichlid-like fanning and vigorously defending the eggs. Younger specimens that are below spawning age should be kept in a group, and do well in a peaceful community setup.

Flag Fish can and should be kept in a well planted tank, though they may nibble the plants, but daily feedings of soft green algae cultured on stones usually prevents that. They eschew the bright light of well planted aquaria, so floating plants over the main swimming area will keep your Flag Fish group continually visible. Flag Fish prefer their water slightly alkaline; pH 7.2 is best, and moderately soft, with temps between 68 and 75. You'll want to keep your tank very well planted, because once they mature, Flag Fish always breed, usually at the base of a plant. He drives the female hard, and he guards the eggs and fry with vigor. The plants are necessary so she can get out of his line of sight, and one night she should be removed to another container to escape his attentions.

The eggs hatch in a week at 75 degrees, longer at warmer temps. He's an attentive father, and keeps his flock close by at all times. The youngsters are easily raised, taking live baby brine shrimp as soon as they are free swimming, transitioning to larger foods and algae as they grow. If you swipe the fry to raise them yourself one evening, he'll promptly look for another female and spawn again.

Florida Flag Fish are among the easiest killies to find, and better fish stores usually have them on their lists.

10-08-2010, 08:20 AM
Another home-grown beauty of a killie is the Bluefin, Lucania goodei.

Native to our southeastern states, including Georgia, South Carolina and Florida, Bluefins top out at 2 inches, and males have all the color, as both his dorsal and anal fin are rich blue with dark red rays and are topped with black. Those fins really glitter as the fish moves through tank. Both sexes have a dark line running from the mouth, though the eye, to the base of the tail. Both male and female are silvery below the line and clear green, with a dark lattice along the lines of scales, above it. He has a blush of rich red at the base of his tail. Her fins are perfectly clear, and she's about a half inch smaller than her mate. You'll see the male's fins really flashing blue if morning sunshine hits the tank.

Both sexes are spirited and lively, the male especially, with those spectacular fins. This species is found in heavily vegetated streams and ponds, meaning a well-planted aquarium is indeed the best place for them. They prefer bright, clear water that's neutral to slightly acidic and soft, and are ideal for a 29 gallon or larger tank. They aren't at all a tropical fish; 72 is their temperature. You can keep a whole school of bluefins, since they travel in schools in nature. Though they don't like to be crowded, you can keep them with other small temperate species, like White Clouds (Tanichthys albonubes), although a school of just bluefin in a properly set up and lighted planted tank is a pleasure few have experienced these days.

In feeding, it'll be a while for them to take anything other than live foods if your bluefins are wild caught. Fruit flies, mosquito larvae, baby brine shrimp, Daphnia and Grindal worms, the latter halved before feeding, should all be on the menu. You can gradually wean the Bluefins on to small pelleted foods if you start mixing a few, gradually more, in with the Daphnia. Though he won't be quite as brilliant without just live food, it is in their best interest to add prepared and frozen foods to their diet. Bluefins should be given tiny meals often, up to every four hours, since they are grazers. They will be in their best health if your feed in that schedule. They do far better in a planted aquarium than other types.

In breeding, the school often does so en masse, but the fishes must be fed copious amounts of live foods for females to have valid eggs. The eggs are scattered among fine-leaved plants, where they'll stick until they hatch a week later. The fry are quite small, so you'll have to culture Rotifers to feed them when they become free swimming, since it'll be some time - as many as 10 days - before they grow enough to take BBS. The fry aren't difficult to raise.

Like most small schoolers Bluefins can live up five years, properly kept. Set up a tank, get some and confuse your friends on what they are, since Bluefins are far from common in shops.


Moving toward the African continent is one of the most long standing fish in the hobby, Aphyosemion australe- the Lyretail or Cape Lopez killie, native to heavily vegetated rain forest streams of The Cameroon and Angola.

This is a borderline tropical killie, and does best between 68 and 74 degrees, but for breeding it should be very slowly raised to 78. Soft, acidic water (pH 5.5 to 6.8, gh under 5) is required with this species, and filtration through peat moss is very helpful. Partial water changes should be done at least weekly, no more than 20 percent, and only at night, to avoid stressing these lovely fishes. Planted tanks are ideal, indeed needed, for these fish, helping with the stability they require. The bright light of planted tanks should be filtered with floating plants over the main swimming area for best results. Given proper conditions and feeding, australe are not at all delicate and will live quite well in a species tank or with small, gentle schoolers. Lyretails do not like to be crowded, so keep a group of these beauties in a 29 gallon or larger. Sex ratio is two to three females for every male. Australe is very peaceful in such groups, but males may flare at each other for choice real estate.

The australe tank should be well covered as they jump, usually at night.

Reaching a modest 2.5 inches, females less, the males are showpieces. In health, his expansive finnage is well spread, and are orange, with blue spotting, then dark blue edging. A bright silver-white edge tops the dorsal, anal and the lyre-shaped tail fin. The latter two are spotted with color. His body is green silver, spotted with red, and topped with deep orange, also with dots. His ventral fins are solid orange. She's much less colorful and her fins are smaller, but she too has red spots on her flanks, extending somewhat into the fan-shaped tail. There are several man made color morphs of this species, but in my opinion the male is most attractive in his natural garb. Australe commonly live for five years, sometimes more.

In feeding, live food is best, but australe will happily take frozen foods like freshwater mysis shrimp, bloodworms and tubifex. They will take pelleted foods, but make sure they are top quality. Feed australe small meals at least twice a day.

When mature at two years, australe commonly spawn, usually over fine-leaved plants. The eggs hatch in 10 to 12 days, and it's best for the keeper to take the eggs and raise the fry themselves. Australe fry are tiny, and infusoria (Paramecium is best) is the first food for the fry. Rotifers follow when the fry lose interest in Paramecium, and baby brine shrimp are introduced after the Rotifers are ignored. Australe fry aren't difficult to raise, but must be graded by size, since some fry grow faster than others.

10-08-2010, 08:22 AM
One of the most commonly available and justly popular killifish is Fundulopanchax gardneri, native to forest streams and marshes of Nigeria and The Cameroon.

Called the Blue Lyretail in the hobby, gardneri males are clothed in a almost luminous steel blue; that blue liberally scattered with red dots that go from the head to the lyre-shaped tail, including the anal fin, which grows silver white extensions as the fish ages. The blue is electric in the anal fin and the bottom of the tail. Dorsal fin and top of tail is yellow, the dorsal spotted with and edged with red and electric blue. Gardneri males are truly brilliant, and when light hits him just right, nearly blinding.

She's less decorated than her mate, but is attractively colored golden yellow when sexually mature. She has dots of red all over, including her unpaired fins. Reaching a bit over two inches, the female smaller, Blue Lyretails are one of the most hardy of the small killifishes.

That said, they shouldn't be taken for granted and plopped in your alkaline, hard water tank. Gardneri are rain forest stream fishes, frequenting aquatic plant stands in nature, thus should be kept in the soft, acidic, well planted tanks. Gardneri does not do well above pH 7.0, and prefer their temperature in the low 70s. A gentle current from low GPH power heads is appreciated by this species.

Small as they are, with males topping out at 2.25 inches, females a half inch or so less, Gardneri is quite long lived, and a keeper can enjoy these fishes for up to 10 years. They can be kept with similar small fishes, but in a species tank a group of this species, a trio of females to every male, is a pleasant sight. Gardneri are an active, vivacious species.

In feeding, live food, including live baby brine shrimp, is best, and is necessary for the female to have valid eggs. They will take small pelleted foods, and enjoy frozen foods like Mysis shrimps and bloodworms. Foods must be small, since these fishes have small mouths. Feed your charges light meals twice a day.

In a soft, acidic planted tank, mature gardneri breed regularly, the female laying eggs every ten days. A breeding mop setup is commonly used if one purposely wishes to raise the fry, since the pair will eat the fry if left in the tank with them. In a regular planted tanks, the spawn is either placed among low plants or secured to floating plants. Eggs hatch between two and three weeks with the fry free swimming almost immediately. The fry must be graded for size, since they will eat their smaller siblings. The fry are large enough to take live baby brine shrimp and microworms. Obviously, given the extended breeding period, fry must be graded for size.

One of the most popular and brilliant of the killies, and available in at least 15 regional variants, Gardneri are one killie for beginners to try.


One of my personal favorites is Aphyosemion bivittatum, native to the border region between Nigeria and The Cameroon.

Found commonly in shady pools that are thick with aquatic plants, bivittatum, called Two Stripe Lyretail in the hobby, possesses a beautiful translucency that no photo can capture. Reaching 2.5 inches, it's difficult to nail down the colors of the male fish, since it changes depending on pH, temperature, hardness, and mood. The colors can include oranges, reds, blues, yellows and greens, and all those colors can be on a single male. There's also a dazzling number of regional variants. Both sexes have a pair of lines that run from the nose to half way on the male, and to the tail of the smaller female of the species. The male has a lyre-shaped tail, commonly speckled and lined with red. His dorsal fin is tall and comes to a point, and in sympathetic surroundings and with at least occasional live food, is high and proudly displayed. His anal fin, also expansive, is usually lined with waves of color and capped with bright white. The female reaches two inches and is similarly colored to her mate, but much less intensely. She can have red edging on her unpaired fins. Both sexes have bright silver eyes.

Though tank bred two-stripes can be kept up to pH 7.4 and moderately hard, it's in the soft and acidic planted aquarium they live and look best, and filtration through peat moss intensifies the male's colors. This is one killie that's accustomed to other fish in its clime, so one can keep small schoolers, but not fish that will pick at the male's expansive finnage; tetras, small catfish, and the like, are appropriate tankmates with the killies.

Bivittatum prefer to stay near the top of the tank, and in a well-planted aquarium with bright light, these fish look extremely attractive moving though the light and shadow of floating plants, which should be numerous over the main swimming area. As they developed in shady pools, floating plants are essential in the highly lighted planted tanks. The more plants in aquarium, the better these fish like them.

They tend to dart, stand still, and repeat, especially when food is of the offing, but are quite active and perfectly peaceful in pairs and in groups, the latter how they should be kept. Temps are 72 to 78.

This species does best with live food, but pellets and frozen foods as high in protein as available can be used. However, for valid eggs, lots of live food is mandated. They are very fond of worms and small crustaceans and mine take live Grindal worms and young Mysis shrimp with great gusto. Twice daily light feedings are best for these fish. Given soft water in copiously planted aquaria and with stable conditions, bivittatum is quite hardy, living five years, sometimes more.

Bivittatum can be described as just add water and fine-leaved plant breeders. Live food for a few days and a slow raise to 80 degrees and the plants will soon be full of eggs. Bivittatum breed most commonly early in the morning, just past daylight, so the keeper must be quick to remove them before tankmates find the eggs. They hatch in 12 days at 73 degrees, and longer at higher temps. Fry have to be graded for size as soon as they are free swimming since two-stripe fry vary widely in size. Live baby brine shrimp and microworms are the first foods for the youngsters.

One of the true beauties of the killie clan, bivittatum is a lovely species for prospective killie keepers to try.

10-08-2010, 08:25 AM
The first killie I kept and still adore is Roloffia occidentalis, the Red Aphyosemion.

Native to forest creeks and streams in Sierra Leon and Liberia, the common name applies to both sexes of this beautiful species. The male tops out at 3.5 inches, females about an inch less.

Both have golden flanks that are lined with rich red, blending into deep magenta that intensifies as the fish age as you move down the fish. As per usual, the male's colors are much deeper than his mate. His throat and lower lip is blue, and unpaired fins a rich magenta - the dorsal and anal fin edged in deep blue, and the tail lined with red and centered with rich blue. The anal fin sprouts a small group of white rays once he passes his second year, when both sexes become heavier bodied. Up to that point they are rather slender fishes.

Though her magenta isn't quite as intense as her mate, she too is very much a showpiece. Her fins are edged in bright white and her anal fin feathers out with age. Her red continually deepens as she ages. Both sexes have silver eyes. The man made version of this species with much more yellow is called Golden Pheasant. Only in their fry will you see how beautiful the natural fish become.

This is a soft water species and cannot be kept above pH 7.0. Best is pH 6.5, gH under 5. A temperate species, Red Aphyosemions prefer temps between 68 and 75 and does best in a thickly planted aquarium at least 40 gallons in size. Floating plants are necessary over the main swimming area, and both substrate and background must be dark. Tanks must be firmly covered, as this species is an avid jumper.

A keeper can expect this species to live up five years, sometimes twice that. When mature at two years, Red Aphyosemion commonly breed, usually just after daylight. Feeding them at least occasional live food usually results in a spawn once they are sexually mature. Feeding live food for a week or so and the pair will breed every ten days like clockwork, scattering adhesive eggs among fine leaved plants. At 72 degrees the eggs hatch in ten to 12 days, longer at warmer temps, and the fry are large enough to take live baby brine shrimp when free swimming. The fry vary widely in size, and must be graded to prevent cannibalism.

However, in part of the range of this species it behaves as an annual, since it frequents small pools and seasonal creeks, so fish imported from those regions live under two years. Thus, the annuals are substrate spawners; depositing their eggs deep in peat moss. Once spawning is complete, remove the peat and seal it in a plastic bag and put it in a dark, cool area (65 to 70 degrees) for a month. Then put the egg-laden peat back in a tank filled with soft, acidic water. Eggs hatch within a day in temps in the low 70's and fry are almost immediately free swimming and will take live baby brine shrimp. The fry aren't difficult to raise but must be sorted for size.

Live food of the insect and crustacean nature are best for these fishes, but they will take prepared and frozen foods, especially if they are captive raised fishes.

As you see there are two versions of this species - those that live long and those that are annual fishes. Thus, one must search for those that live long since they become such beautiful, colorful fishes as they age.

Fairly difficult to find, but well worth the search for the prospective killie keeper.


Called Golden Wonder in the trade is Aplocheilus lineatus, native to southern India and Sri Lanka (Ceylon).

Perhaps the most commonly available killie, lineatus has been around long enough the red and other colors the natural male possesses has been bred out, so if you see a killie sold as a Gold or Golden Wonder, it is this species.

Naturally, males have deep crimson edging on his unpaired fins, especially on the fan-shaped tail, and in some specimens that tail can be entirely red and dotted with pale blue. The body is red, deepening to magenta and glistening black as you move from the top of the fish. Golden stripes run along the lines of scales and each scale glitters with electric yellow highlights.. Males reach five inches, females an inch less; her lines over her much paler yellow are wider and darker, and her fins are rounded. In wild caught examples they are edged with red. She has dark banding from the dorsal to the tail.

Both sexes have shining green and silver eyes. Young males look just like females; it's after their first 16 months they develop their mature color and finnage. In certain light both male and female can appear shining green with burnished gold highlights, and there are many wild regional variants of this species. In any light, an all together attractive killie.

Like most larger killies, lineatus is highly predatory to fish small enough to eat, and that includes his fry, so choose tankmates with care - large enough to not be considered food but peaceful enough to not harass the killies. Small catfishes, larger tetra species and peaceful cichlids are perfect as tankmates.

Lineatus stays near the top of the tank, watching for live food to present itself, thus foods, either live, frozen or prepared, should float. A confirmed carnivore, all foods should have meat protein within for best results. Dropsilia hydei would be a perfect live food for these fish, and can easily be dusted for color or lipids prior to feeding. Any suitably-sized crustacean will be taken, as well as fish fry, but use the latter food very sparingly. An avid and accomplished jumper, a lineatus tank must be completely covered, since if one jumps out, all of them will follow. Nylon screens should be secured to close any gaps, no matter how small.

This is another killie that does best in the thickly planted, soft water aquarium. PH should be under 7.0 and moderately soft. Floating plants over the main swimming area will make lineatus very comfortable in your tank since they eschew bright light necessary to very well planted aquaria.

As a larger killie, a larger tank is warranted, say a 55 gallon and up for a group of six or eight. Neither males nor females care for each other, so one must have both space and cover until the group reaches equanimity. Subservient males don female rainments. Lineatus likes his temps in the mid 70's - for breeding it should be slowly raised to upper 70's to 80 degrees. Copious amounts of live food should be offered for a week, and soon large eggs are secured to fine leaved, and sometimes floating, plants. The eggs should be removed and hatched separately since both sexes will eat the fry.

The eggs hatch in two weeks and the fry can take live baby brine shrimp and microworms immediately when free swimming. The fry will have to be graded for size almost daily, since some grow much faster than others. About half the fry will possess the natural coloration once mature, the others the 'Golden Wonder' form. Adding natural specimens to the group and soon all fry will possess the very attractive natural coloration. You can expect at least five years from your charges.

One of the most satisfying and hardy of the commonly available killies.

10-08-2010, 08:30 AM
Perhaps the grand potentiate of the killie clan is Fundulopanchax sjoestedti; the Blue Gularis of The Cameroon, The Ivory Coast and Nigeria.

This killie was the first aquarium fish to be photographed in color, in 1920, and started appearing in aquarium publications soon after.

Reaching nearly six inches and is very widespread in coastal rain forest streams of West Africa, only one form of this species can be considered 'blue', That form has a metallic blue body, loosely barred with black on the back half of the fish, with closer barring and lining as you move toward the head. A flush of deep orange runs from the bottom of the caudal peduncle spreading richly to the middle of the expansive three-pronged tail. Variations, both natural and man-made, as almost as numerous as pebbles on a beach, so if you want to keep this species, ask for it by scientific name.

This killie, does best and looks his best in the soft, acidic planted tank, and doesn't look nearly as good in slightly alkaline waters. Though it will eat much smaller fishes, including his own fry, they can be described as near perfect community fishes. Tetras that grow over two inches and Corydorus species catfishes are the best tankmates.

She's about an inch smaller than her mate, but develops an attractive yellow cast, spotted with red in some populations, as she ages. Like most of the larger killies, sjoestedti live many years, averaging between eight and ten. This species spends most of its time in the lower third of the tank. Best ratio is one male to at least three females. In a large enough planted tank, say a 75 gallon, a whole colony of these killies can be kept, and purely to attract females, males can look truly stellar in such tanks.

You'd be depriving yourself of a beautiful show if you don't feed these fishes live food. They are very partial to crustaceans, like highly enriched live adult brine shrimp, adult freshwater mysis shrimp, larger cladocorans like Daphnia magna, and the like. If one keeps small shrimp, the excess would be appreciated by this species.

They will take high quality pelleted foods, especially if you introduce them with the crustaceans. They like them more if the pellets are emulsified in products designed for colors or lipids, contact me for brands and sources. Best feeding schedule is small meals thrice daily. This species likes his temps in the low to mid 70's, say 72 to a max of 77.

Sjoestedti breed readily when mature at two years old, depositing large eggs that are slightly adhesive on the substrate or on plants early in the morning. They are easily removed by pipet and hatched separately. It can take up to two weeks at 75 degrees for the eggs to hatch, with the fry free swimming soon after. They are large enough to take microworms and baby brine shrimp and progress rapidly. They must be graded for size but all can be half grown in six weeks.

This species has jumping down to an art, so their tank most be tightly covered with any gap closed by nylon screening. They can leap through a half-inch gap with ease, and if one goes, all the others of its kind will follow, so seal your tank up tight.

A lovely species, and quite hardy well kept. A keeper can expect his charges to live around a decade.


Native to the La Plata region of Argentina is the Argentine Pearl Fish - Austrolebias bellottii.

Another species of multiple variations, even waterways a few miles apart can look quite difference in colors and body size.

The original Argentine Pearl Fishes vary in the way the light hits, feeding and mood. The male looks quite attractive with an indigo blue scattered with lines of pearly spots. Sometimes he is olive, sometimes yellow. When kept in the soft water tank and fed primarily live food he spends a lot of time blue with pearls.

She looks completely different, with a clear brown over silver, and brown striping, She has lines of brown in all her unpaired fins. Males top out at three inches, females a half inch or so less. This is a true temperate killie, doing best about 70 degrees. They really appreciate a planted tank, with floating plants above the main swimming area. This isn't a community fish so must be kept in a species tank.

This is an annual species, depositing spawns in a peat moss substrate, that's been boiled once to reduce acidity. The peat is removed, bagged still moist, and stored in the dark for two weeks. Eggs hatch best when when the the temperature while in storage doesn't exceed 65 degrees. When the peat is returned to a soft water tank the eggs hatch almost immediately. The fry are avid eaters to say the least, so plenty of live baby brine shrimp must be on hand, Adding small pelleted foods with the shrimp gets it into their heads that the pellets are food, meaning transitions to prepared foods is smooth. The fry grow very quickly, and can be full grown in six weeks.

Pearl fish can live three or four years kept at 68 to 70 degrees but have much shorter life spans when kept warner. Adults do and look best with at least occasional live food, like Daphnia, white worms and the like. They will learn to take prepared and frozen, but won't be as vigorous or colorful without live foods.

Though some of its relatives are more colorful, the Argentine Pearl Fish has an elusive charm that's difficult to describe.


One of the most ornate and brilliant of all Rivulus species is R. strigatus, the Herring-Bone Rivulin, native to the interior regions of Argentina and Brazil.

Reaching just 1.5 inches, males of the species possess a deep red herring-bone pattern on a bright bluish green body that can appear luminous when light hits him just right. His unpaired fins are all tipped with red, and can be yellow to orange. Females have a similar pattern, but not as distinct as her mate, She is three-quarters of an inch smaller than he. Like all Rivulus species, the caudal fin is rounded, and she has the characteristic Rivulus spot on her upper caudal fin.

Small as they are, this species doesn't like to be crowded, so at least a 20 gallon tank is necessary for a group of these lovely little fishes, at least three females to every male, Like all Rivulins, this species tends to stay still, using their pectoral fins to stay in place. They often pose head down and tail up. This species doesn't stop and pose as much as other species of Rivulus.

However, when food hits the water, especially live food like fruit flies and Daphnia, strigatus is quite sprightly. Foods, as for all killies, should primarily be live for best results, but wild caught examples will have to be slowly trained to take small pelleted and frozen foods. This species should be fed tiny meals three times a day.

This species should be kept in well-planted aquaria equipped with floating plants over the main swimming area to mimic the shaded streams this species comes from. They like their water neutral to slightly acid, and soft. More acidic, say pH 6.5, will prevent this species from contracting disease. Temperatures are in the mid 70's for general maintenance, when breeding it should slowly be raised to 80. This species is a perennial, and can live a surprisingly long time.

You'll know when breeding is imminent when males start trying to chivvy females over fine leaved plants. They like to breed high among the plants, scattering adhesive eggs. If the adults are fed live food they'll neither touch the eggs nor young. They usually breed just after daylight.

One should remove the eggs carefully and hatch them in an unlit tank, as they usually don't hatch in lighted tanks. The eggs hatch within two weeks at 75, much longer warmer. The fry are tiny, so Rotifers should be offered first, followed by baby brine shrimp when the fry lose interest in the Rotiffers, It'll be some time before the fry are large enough to take microworms and small pelleted foods.

There are dozens if not hundreds of regional and man-made versions of this species, but my description is the first imported in 1933. Ask for them by scientific name if you wish to keep this species, and be aware, there are several synonyms. The herring-bone pattern is diagnostic, though.


Native to eastern African pools is Northobranchius rachovii, our last killie.

What makes this killie worth having is the males are unbelievably brilliant, just electric, and no photo can do this fish justice. Reaching an inch and three quarters, the rather bland female a half-inch less, rachovii is easily kept with a few tenets. First, they must be kept in a soft and acidic (pH 5.0 to 6.5, gH under 5) planted tank equipped with floating plants. Males do not get along so one male to a number of females. A 29 gallon tank is sufficient.

He's deep red with electric blue striping, and electric accents on all unpaired fins. When the male hits the light between floating plants he's almost blinding. There are several variants, both regional and man-made, but in one and all, the males are the show.

They like their temperatures in the mid 70's, and live food is mandated for best results. Things like fruit flies and Daphnia are deeply enjoyed. They will learn to take small pelleted foods, especially if you start adding some to a Daphnia meal, but for valid eggs, is has to be live food.

This annual killifish is a soil spawner, and must be kept in a tank with thrice boiled peat moss as the substrate. He and his chosen mate get side by side just above the peat, and the eggs are fertilized as she pushes them into the peat. The peat is removed, bagged, and held in a cool, dark place for two months. Placed in a soft and acidic darkened tank the fry will be hopping around the top of the peat within an hour. As soon as they are free swimming, Rotifers are added, and the fry grow quickly and will be ready for BBS in days. They'll be almost full grown in a month.

Despite being an annual species rachovii can live past a ripe old age of three.


There are many, many different kinds of killiefish, and variations of almost all of them. Though they have a reputation of being hard to keep, it's far from the truth, as in a soft and acidic tank and at least occasional live food, killies are among the most hardy fish one can buy. I encourage you to research killies further as several books are available on the subject and there is the national organization that takes members from all over the world.


Lady Hobbs
10-08-2010, 08:42 AM
Another good read by Dave. Thanks for another great article.

02-28-2012, 04:49 AM
Thanks, Dave. I used to keep plains killifish (http://nas.er.usgs.gov/queries/factsheet.aspx?SpeciesID=694) in my 20G tank now and then when I was a youngster--we'd catch them in irrigation ditches. They always seemed rather exotic compared to the other native fish, even quite colorful when the breeding urge struck. But I always let them go after a week or so since they never seemed to get the hang of flake food. Interesting little fish, though; I wish it had occurred to me, back then, to give them live food. I might have to try some of their tropical cousins someday.


02-28-2012, 04:53 AM
Great write up Dave, I have a great passion for killis!

03-03-2012, 12:44 AM
I know this is a two year old thread but it's a sticky. You know what would really rock this thread? Pictures!! Killi's are such beautifully coloured little jewels.