Austrolebias Nigripinnis Molino (Anual Killi)

Annual killifish are found in both Africa and South America. South American species are found throughout the continent, from Venezuela to Argentina, while only one genus, Nothobranchius, is found primarily in the eastern regions of Africa. The South American group includes an enormous array of genera and species that vary in size, colors, patterns, and finnage. There are species with bodies under 2 inches to relative giants at 6 inches or more. Bodies vary from short and deep to large and elongated, incorporating delicate pastels overlaid with iridescence, patterned in spangles and stripes. There are plain, rounded fins with spots, stripes, and borders, and those that elaborately flow in multitudes of colors and patterns. Together with their extraordinary breeding and survival strategies, the 28 or so genera and hundreds of species, subspecies, and recognized populations make South American annual killifish one of the most interesting and underappreciated groups of fishes available in the hobby today. The term “annual killifish” refers to killifish that live their entire life in temporary bodies of water, those that fill when the local wet season commences and completely desiccate during the ensuing dry season. To thrive and propagate in perhaps the most demanding and dynamic environment faced by any aquatic vertebrate, these marvelous fishes have developed an extraordinary and complex web of inter-related and mutually supportive survival adaptations. These include extremely rapid growth, very early sexual maturation, and great fecundity.

Egg Development

The deposited eggs proceed through a sophisticated series of developmental events that begin immediately after spawning and continue at various rates through the remaining life of the pool and the subsequent dry period. Depending on very complex environmental interactions, annual eggs do not develop at uniform rates, but rather respond with periods of development, interspersed by one or more periods of suspended development called diapause. All these occur in response to a combination of environmental cues. These environmental cues trigger both the onset of the diapause events as well as the resumption of the incubation process between them. In addition, individual eggs do not respond uniformly. Some remain at one of the diapause stages while the others resume development. After one full cycle, the substrate will typically hold eggs at virtually every stage of development. This episodic developmental process is part of an astonishing adaptation to the unreliable timing of the onset of wet seasons and acts as a fail-safe defense against the occurrence of long-term droughts. What appears to be random variation in the developmental cycle is, in reality, a sophisticated survival mechanism that guarantees that some eggs will always be ready to hatch despite extended droughts, erratic short-term rain events, or extended periods of flood.

Returning Rains

Whenever the rains do return, inundation initiates a complex and radical change in the environment around the eggs. That triggers completely developed eggs to hatch within hours and those near final development to complete the process within days. Depending on the species, the resulting fry will reach sexual maturity and breed in a few weeks to a few months. They will bury their eggs in the substrate from which they recently emerged, seeding the future generation. At times, annual rains are intermittent. Pools fill for very short periods and then dry again, perhaps until the following cycle. Under these circumstances, natural selection tends to favor the fish that most rapidly mature and breed, passing these characteristics to the next generation. All life processes are accelerated, including the aging cycle, which is more or less synchronized with the wet cycle of the pool. The term “annual” comes from this natural annual cycle as well as observations of lifespan in captivity. Wild caught annual killifish often expire within a year of age, but after decades of domestic husbandry, many species will live to 1½ years or more. A full understanding of annualism in killifish is still a subject of intense scientific study, and a complete unraveling of this fascinating process is, no doubt, some decades off.

Breeding South American Annuals

However, if one can tolerate the uncertainty, breeding South American annual killifish presents a unique challenge that many find seductive. In essence, the breeder must employ a material that substitutes for the pool substrate and a storage regimen for the developing eggs that substitutes for the wet-dry season. Each adds a dimension to fish husbandry not otherwise found. Fortunately, e easy and effective solutions have been developed by killifish hobbyists over the last 50 years.

Spawning

Isolating the breeders and preconditioning them with live or high-quality frozen foods for a week prior to spawning will greatly increase the chances for success. Although breeding can be accomplished in a permanent aquarium, a special breeding setup often provides better results. Colloquially known as divers, South American annuals completely submerge in the muddy bottom of the pool substrate to breed. The material of choice to simulate this substrate is a good grade of fertilizer-free peat moss or fiber. To prepare the material, boil it for a few minutes to kill any unwanted organisms and to ensure that it will sink.

Spawning Targets

To trigger the spawning response, a spawning target that mimics the pool substrate is required. If breeding is to be done in a permanently set up tank, select a plastic container with a depth of at least three times the length of the largest fish to be bred and cut a hole in the container cover that is two to three times the breeder’s width. This hole allows the fish to enter and leave while minimizing the entry of food or other contaminants. It also minimizes the amount of peat that the fish will throw up and out of the container during spawning. Add gravel or other weighty material to the container to ensure it will sink in the tank. Fill the container halfway with water from the breeding tank, and add some prepared peat. Skim off the peat that does not sink, and add more water and peat until the container is completely filled and the peat layer is at least 50 percent deeper than the length of the largest breeding fish. Pop on the cover and slowly immerse the container into the tank so as not to disturb the peat. The annuals will eventually find the container, enter it, and spawn. Remove the container after one week. An easier, and ultimately more productive, method is to use a drum bowl or other container as a temporary spawning site. Fill the bowl with water from the breeder’s tank, and add peat as above until the desired depth is reached. For most species, a 2-gallon drum bowl is adequate. After the peat settles, add the breeders and cover the tank or bowl. The female will generally release her full complement of eggs within 8 hours, 24 at most. If the species is large, add an air stone. Do not feed during this time. Remove the breeders within 24 hours, or earlier if the female is being abused.

Incubating

Up to this point, we have simulated the pool substrate, and hopefully, the fish have deposited their eggs deep within it. Pour out the contents of the container through a fine net, capturing the peat. While the peat is in the net, squeeze out as much water as possible. Then place the mass of peat moss between several sheets of newspaper, roll it up, and allow the bundle to dry at room conditions. Examine the peat after 24 hours; it should have a trace of dampness but not be wet. Pinch a small quantity between your fingers—if no water emerges, the peat is dry enough. If still too wet, repeat the process. When ready, pack the peat in a plastic bag, mark the date of packing, and add the recommended incubation time for the species. Some hobbyists store in a temperature-controlled incubator, but most store the eggs at room temperature. The eggs will now go through their complex incubation process without any additional input from the aquarist. Incubation times vary for each species, from three to seven months or more, and are especially dependent on the temperature at which the eggs are stored. And although advanced hobbyists do manipulate incubation times, it is not recommended for those without extensive experience.

Hatching

There are two methods to determine whether the eggs are ready to hatch: test hatch or direct examination. Highly experienced hobbyists are able to find developed eggs among the particles of peat and visually determine whether they are fully embryonated. However, the skill is an acquired one that many killifish hobbyists never really master. Most hobbyists test hatch: Shake the peat in the bag, remove a small quantity, and place it in a one-gallon tank or clear container. If the eggs are ready, they will hatch within 24 hours, sometimes much sooner. If no eggs hatch, reseal the bag, store for another four weeks, and then repeat the test. When the test is positive, prepare a 1- or 2-gallon tank with active tank water, dump in the peat, and stir to wet it as much as possible. Most of the peat will sink in a few hours. When successful, the event is what killifish hobbyists refer to as the hatch. There is nothing quite like it—it is an event one has to experience to truly understand.

Feeding

The larger fry can feed on newly hatched brine shrimp, but the fry of smaller species require proportionally smaller foods during their first week of life. All killifish fry, regardless of size, consume microscopic foods immediately—paramecia, infusoria, etc. If the hobbyist does not raise microscopic foods, a clump of seasoned java moss, Riccia, or hair algae can be added. The latter in particular fosters enormous colonies of microscopic life. Newly hatched brine shrimp can be taken within days and should be offered through the first several weeks. After a few weeks, microworms, then whiteworms, grindal worms, or finely ground prepared foods can be added.

• Common Name – Austrolebias Nigripinnis Molino
• Origin – South America
• Diet – carnivorous
• PH Range – 4 – 7
• Temperature – Tropical 26°c – 28°c
• Breed Type – Egg Layer
• Maximum Size – approximately 7cm
• Sex – Male/Female Pair