African Plant-Spawning Killifish (Full Article)Author: Charles Nunziata
The term “killifish” describes a large group of fishes that are found everywhere except Australia and extreme southern and northern latitudes. They are divided into two major groups reflecting their reproductive strategies. The plant spawners inhabit permanent water and deposit their eggs in vegetation. For these types of fish, embryonic development is a continuous process. Soil spawners, the true annuals, inhabit temporary bodies of water and deposit eggs in the substrate. Embryonic development is episodic—the eggs go through a complex series of developmental steps.
The majority of killifish are plant spawners with hundreds of species, subspecies, distinct populations, and color phenotypes—too many for a single article. For this reason, I will cover only the African plant-spawning species.
Plant spawners do well within a general hardness range of 80 to 200 ppm and temperatures between 68° and 80°F. The breeding of some species requires a more acidic pH and lower hardness than others. Lower temperatures are well tolerated, but breeding activity in general declines. The plant spawners are not disease prone, requiring nothing more than regular water changes and good nutrition to remain healthy. To develop properly, their eggs must remain in water or be stored on damp media for one to three weeks. A small subgroup, the “switch spawners,” is known to deposit eggs in bottom vegetation or the substrate. Their eggs take longer to incubate, from three to six weeks.
The most popular plant-spawning species belong to the genera Aphyosemion, Fundulopanchax, and Epiplatys. Body length varies from barely an inch to more than 6 inches, but most are 2 to 3 inches total length. A few body plans are repeated among the genera, but fins vary from small and rounded to large and spectacular. Colors come in every conceivable combination of pale to vivid, and markings range from delicate to bold, incorporating stripes, bars, and spots.
Aphyosemion species are among the most commonly kept killifish. This very large genus is divided into a number of formal and informal divisions that serve to identify mutual characteristics. Most Aphyosemion spp. are 2½ inches or less, and their eggs hatch in two to three weeks.
The subgenus Chromaphyosemion, known colloquially as the bivittatum group, consists of mostly small and easily bred killies that feature very colorful bodies and well-marked fins. For example, locations of A. bitaeniatum have long unpaired fins in various shades of yellow, red, blue, and green. A. bitaeniatum “Lagos” and the “Ijebu Ode” population are fine representatives of the group.
Members of the subgenus Kathetys, known as the bualanum or elberti group, are more robust, with deep-rich blue or green bodies overlaid with thin, dark-red bars. Fins are large and similarly marked. The populations from N’dop and N’tui are particularly stunning.
The subgenus Diapteron includes arguably the most colorful of all killifish. Small (growing to less than 2 inches in length), each of the five species of Diapteron exhibit exquisitely beautiful bodies overlaid with brilliant spots, often extending into the fins. These cool-water jewels from the deep forest are not for the beginner.
The many species in the subgenus Mesoaphyosemionrange from 2 to 2¾ inches in total length. The variation within this group is enormous. There is A. australe, with itselaborately extended fins, the elegant simplicity of A. celiae,with its sparsely marked orange body and dramatically edged caudal, and the garishly colored and exotically marked A. ogoense group.
The Congo Basin gives us the elegans group, represented by the A. christyi and A. cognatum complex. A. christyi are characterized by relatively long and elaborately marked bodies and unpaired fins that often extend into streamers. There is an Aphyosemion to satisfy every taste.
Switch Spawners (Fundulopanchax spp.)
Reflectingtheir propensity to deposit eggs in both vegetation and the substrate, the switch spawners belong to the genus Fundulopanchax. Their eggs incubate in water or on damp media, hatching in three to six weeks. Many are large, exceeding 3 inches, but lackthe variety in body and fin configurations seen in Aphyosemion spp. At 6 inches, F. sjostedti, the blue gularis, is the largest of the genus and the emblem of the American Killifish Association.
The most popular subgenus, Paraphyosemion, includes the well-known F. gardneri group of species. They are well proportioned with elaborately patterned and colorful fins and bodies. In contrast to many Aphyosemion species, F. gardneri are gregarious, vigorously exploring their habitat. They are often included in community tanks with similarly sized inhabitants. All are hardy, and most are quite easy to breed, making them ideal fish for people new to killifish.
Although colorful, Epiplatys species lack the dramatic finnage of Aphyosemion species. These surface-dwelling ambush predators have a pike-like appearance, accentuated by flattened heads and backs, and small dorsal fins placed well back on the body. The fasciolatus types are large, often exceeding 3 inches at four or more years, and among the longest-lived killifish.
Members of the sexfasciatus/infrafasciatus group are moderately large, reaching up to 3 inches in length, and tend to be more colorful than the fasciolatus types. The baroi population from Cameroon is a striking example of this group. The multifasciatus group is somewhat stockier, with muted colors but more dramatic body markings. Recent collections have found somewhat slimmer species with black on the flanks, a pattern not seen in any other multifasciatus. They are the only Epiplatys group considered difficult to propagate. E. chevalieri and the beautiful E. ansorgii “Massana” are available in the hobby.
There are several Epiplatys not closely associated with specific groups. One that often appears in literature is the diminutive E. annulatus, with its dramatic broad bars. Because eggs are exceedingly small, this species is commonly maintained in well-planted aquariums and the fry are periodically removed.
The group collectively known as “lampeyes,” named for the bright, reflective silver, red, or blue regions around their eyes, ranges across all of sub-Saharan Africa. The best-known member is Poropanchax normani, a small killie with large, bright-blue eyes, and the larger Procatopus aberrans, featuring adeep, partially iridescent blue body. Plataplochilus miltotaenia is another exquisite lampeye, having an electric-blue, iridescent body, yellow highlights in the fins, and a dramatic carmine line along the flanks from the operculum to the caudal peduncle. Unfortunately, most of the numerous lampeye species are rarely seen in the hobby.
Other Plant Spawners
There are a number of plant-spawning genera that are monotypic (only have one species) and also uncommon. One of note is as spectacular as it is unusual. Large at 6 inches in length and gorgeously colored, this decidedly minnow-like killie is found in enormous schools in Lake Tanganyika. The appropriately named Lamprichthys tanganicanus is not difficult to breed but, due to its high oxygen requirement, is notoriously difficult to ship. They are worth the extra effort, however; a small school in a 6-foot aquarium is a sight one will never forget.
Breeding Plant Spawners
Breeding plant spawners is a simple and straightforward process. Males don’t waste energy in complex prespawning displays. He approaches the female from the rear and side, aligns his body side by side, and, with the pair assuming an S-shaped formation, presses against her, pushing her against the plant. Both momentarily shimmer, and, with a jerk, the female releases her egg and he his sperm, in the same motion pressing the fertilized egg onto the plant. The eggs stay in place with a long adhesive filament, and it, depending on the species, may be placed anywhere or concentrated in a specific region of the plant.
Healthy, well-fed killifish spawn readily. Few require exotic conditions or specific diets to reproduce. Most species have preferences, and egg production increases if these preferences are known and effectively simulated. For wild imports, matching the water and temperature conditions of the natural environment may be important to success. If wild data is not available, data related to similar species is often used.
Successful breeding reports are more reliable than wild data for species that have been in the hobby for generations. In the more than 50 years that killifish breeding has been an organized specialty, killifish breeders have amassed an enormous library of breeding and maintenance information on all but the most recent importations. Much of this information is available on the Internet.
Natural Spawning Method
There are several spawning methods employed by hobbyists. Many prefer the natural method, whereby killies are left to spawn and their eggs hatch in an established and densely planted aquarium. Males will drive females whether they have eggs or not, so sufficient plant cover is necessary to reduce stress on the girls. There are often multiple pairs or other fish in a permanent aquarium, and this will proportionally reduce the egg count, as unoccupied individuals eat eggs as they are spawned. Nonetheless, this minimal-labor method usually produces a number of fry to adulthood. More fry will survive if, when noticed, they are removed and reared in a separate tank.
Spawning Mop Method
A more popular method employs a spawning mop, a device that mimics a plant cluster and allows the easy retrieval and controlled incubation of eggs. The mop is constructed from nylon yarn, typically ¼ inch, in a dark color, green being the most popular. There are several construction methods that can be found on the Internet using the search term “killifish spawning mops.” All methods produce a hundred or more strands of yarn that reach from a float to the bottom of the tank, simulating a rooted plant. If species preferences are not known, both a floating and a sunken mop are provided. The float from one of the mops is removed so it sinks to the bottom, simulating bottom vegetation. The mops should be placed in the region of the tank where the water is least disturbed so as not to unduly disrupt the spawning process.
The most productive method, and the one that stresses the female least, is to spawn one preconditioned pair in a small, dedicated spawning tank. Prepare the tank with live plants or, if the eggs are to be separately incubated, floating and sunken spawning mops. Since females cannot escape the driving males in these small confines, it is important to reduce the time they are together. This is accomplished by preconditioning the female for one week prior to spawning with generous feedings of live and other high-quality foods. When put with the male, spawning will quickly commence and continue more or less until she is depleted, generally within two to eight hours. The pair is then removed. More eggs are obtained with this method in the shortest amount of time and, most importantly, with minimal stress on the female, extending her productive life.
Hatching Killifish Eggs
Because killifish eggs incorporate a strong acellular coat called a chorion, they can be handled without damage a few hours after being spawned, making artificial incubation methods feasible. To harvest the eggs, the mop is removed, squeezed of excess water, and laid on a paper towel. With the fingers, each egg is gently picked from the strands and stored in a small tray of water from an established aquarium. A newly fertilized egg is clear with one or more oil droplets within it. One a few days old will show some embryonic development. An unfertilized egg is white or opaque or may show a white spot within an otherwise clear egg. Bad eggs are removed immediately to eliminate contamination of the healthy ones. The egg storage water should be changed daily or at least every other day, and if this regime is followed, antifungal chemicals are not needed.
A small microscope is helpful to observe embryo development and essential to determining whether an egg is fully embryonated. Look for a fully formed body, alert eyes that respond to changes in light level, and, in many species, pigmentation on the head and coloration around the eye. If a microscope is not at hand, a fully embryonated egg will appear quite black.
Eggs will hatch in two to six weeks depending on species and storage temperature. Not all fully embryonated eggs hatch at the same time. Some lag a few days, resulting in size mismatches among the fry. The late arrivals are at a disadvantage; they may be outcompeted for food or predated upon by their larger brethren. To avoid this, force hatch the embryonated eggs by placing them in a small vial partially filled with storage water. Exhale into the container, and quickly cap it. Shake it vigorously for a few seconds, and place it in a pocket. The high carbon dioxide and shaking about will force all the fully embryonated eggs to hatch within a few hours, greatly reducing size mismatches among fry.
Remove the fry as soon as possible after hatching, and place them in a 1- or 2-gallon container. Add mild filtration or aeration and, to provide micro organisms for smaller fry, some plant matter from an established tank. Tri-weekly water changes are recommended the first two or three weeks, after which the fry can be moved to larger grow-out tanks where they can be weaned onto nonliving foods. Move to progressively larger containers as the fry grow, but avoid tanks of 10 gallons or more until they are at least ¼ inch long. Newly hatched brine shrimp can be fed from the first day through adulthood.
There is a method for those who do not want to pick eggs from mops. The mop is removed, squeezed of excess water, and placed in a polyethylene bag. Add a few teaspoons of water, and tie the bag off so the mop is in a bubble of air. Drops will form inside the bag, indicating sufficient hydration. Examine the eggs periodically, and when a number appear embryonated, remove the mop from the bag, immerse it in the hatching container, and proceed as above. The fully embryonated eggs will begin to hatch in a few hours and the others over the course of several days. This method has the advantage that no time is spent maintaining eggs, yet many fry will hatch and do so at the same time. The disadvantage is that many eggs may be lost to fungus contamination because bad eggs are not regularly removed.
Breed Your Own Plant-Spawning Killies
There you have it. Plant-spawning killifish provide the unique experience of being intimately involved with the reproductive process and observing fundamental biologic systems to a level not otherwise available to the hobbyist. With their small space requirements and astonishing array of different shapes, colors, and finnage, this group of animals provides a truly unique experience. Give a plant-spawning killifish a try; you won’t be disappointed.
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