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Issue: June 2010

Jewels of the Old World: The Aphyosemion georgiae Species Group (Full Article)

Author: Anthony C. Terceira

TERC T 0610
Photographer: Anthony C. Terceira
Vibrant reds and shimmering blues help these killies take on the starring role in any aquarium.

 

Killie hobbyists are increasingly keeping and having success with members of the Aphyosemion georgiae species group (Scheel, 1968), an assemblage of beautifully colored killifish that barely reach an inch in length. This group’s native range is found within the Ivindo drainage basin in northeastern Gabon, and presumably to the adjacent areas of northern Congo.

Habitats and Interactions

Tropical African rainforest drainages, such as the upper Ivindo, have a hierarchical architecture of tributaries, which strongly influence the composition of the cyprinodont community. There are essentially four categories: stagnant pools, permanent rivulets, secondary streamlets, and major streams (Brosset, 1982).

Very small permanent rivulets are insignificant threads of water being 25 to 45 meters (80 to 150 feet) in length and no more than 1 to 3 cm (¼ to 1¼ inches) deep. They house rich, stable communities containing anywhere from 7 to 11 species. Different members of the A. georgiae group are often found living in the same habitat, and it is common to capture more than one member of the group in the same pool.

Brosset and Lachaise (1995) studied the ecology and reproductive biology of these species over an 11-year period from 1970 to 1981. In this area three species, A. cyanostictum, A. georgiae,and A. fulgens, occur in a complex array of sympatric (sharing at least some of the same geographical range) and allopatric (geographically separated) populations. They caught hundreds of A. cyanostictum and A. georgiae in a great number of sites irrespective of the method of capture. On several occasions during their night surveys, they identified A. cyanostictum and A. georgiae males side by side.

 

The Aphyosemion georgiae Species Group

•    Aphyosemion georgiae Lambert and Géry 1968

•    A. cyanostictum Lambert and Géry 1968

•    A. fulgens Radda 1975

•    A. abacinum Huber 1976

•    A. seegersi Huber 1980

 

From their observations, no significant segregation was evident between individuals of different species cohabiting in the same microhabitat. Hence the possibility exists that sympatric relatives are also completely syntopic (two or more species commonly occurring together).

In places where they occur together, there are complex competitive interactions. The consequences of these interactions in relation to sexual selection and ultimately gene flow and genetic divergence need more study. Whether this is unique to this group of species or is common for other groups within the genus is unknown (Collier, 2006).

Aphyosemion abacinum is known from only one locality, which is on a cycle path from the northern district to the frontier of the Congo, about 30 km from Mékambo.

Trouble at the Start

The fish of the A. georgiae species group seldom exceed one inch in standard length. In spite of their diminutive size, they are sparkling jewels in the aquarium. Their bold red colors and contrasting electric blue spots shine like jewels when light strikes them.

Males love sparring and displaying; if adequate cover is provided, little harm is done. Their small size demands that they be kept in small, species-specific aquaria, and different populations should be kept separate from one another.

As with many new additions to the hobby, the first arrival of members of the georgiae species group was met with excitement and anticipation. I remember the first pair that I received from Europe in the late 1970s. I carefully prepared a 5-gallon tank with soft (4 to 5 dH) acidic water at a pH of 6.5 and a temperature of 74°F.

The tank was loaded with Java moss and floating plants. The fish were slowly acclimated and soon began consuming live baby brine shrimp and frozen daphnia. I was prepared to begin collecting eggs and raising fry to share with the entire killifish hobby.

Weeks turned to months and I found few eggs; the adults seemed rather lackadaisical and were not active. I collected few eggs and few fry were growing out in smaller containers. Within six months I had lost the adults and fry.

During this time, other killie breeders seemed to be having very little success with this group in general. Plenty of excitement and attention were being paid to the fish, but their availability within the hobby was not growing.

Eventually and slowly, as this was long before the Internet, information began to appear in various publications. Fish were being kept successfully at lower temperatures and they seemed more active. I remember reading about the original collection of Aphyosemion abacinum: The water temperature was 68°F (20°C).

I had forgotten a simple aquarium-keeping rule: Find out as much as you can about the biotope and habitat of the fishes you are trying to keep, especially if you are dealing with wild or F1(first-generation offspring of wild) fish. I should have known better. I had collected enough native fish during various times of the year to know that ambient air temperatures and water temperatures can be two very different things.

Aquarium Maintenance

Today more and more killie hobbyists are having success with members of this group. Most are keeping them in the mid- to high 60s. Cool water and patience have become their guiding principle.

There are a few things that I have found out over the years. I just wish I could remember the sources of all of the wonderful ideas that have become a part of my fishkeeping.Casual conversations at local and national meetings with fellow hobbyists sharing success and failure are responsible for many of the practices that I use daily.

Sharing, trying, and modifying suggestions helps one develop and grow more successful with any and all types of fishes. Each fishroom is a unique space. However, there are methods common to all fishkeepers and there is no better way to learn about these methods than with face-to-face discussions.

If you are interested in trying to work with this amazing species group, here are some suggestions.

Tips for Success

Keep the pairs or trios in smaller tanks of approximately 5 gallons located in the dimmer parts of your fishroom. Overhead lighting should not be direct. Java moss, which will grow in low light conditions, will work well. If the lighting is too dim for live plants, then the addition of long-fiber peat will work to provide adequate hiding places for both fish and eggs. If there is plenty of cover in the tank, a few fry will hatch and survive with adults.

Another method that has worked well for me is the scoop method, for lack of a better term. I have used this quite successfully;I just wish I could remember where I originally heard this idea.A few pairs or trios of fish are kept in a 5-gallon tank that contains loads of Java moss or long-fiber peat.

I feed them a wide variety of live and frozen foods that include baby brine shrimp, chopped frozen bloodworms, and daphnia—frozen in winter and live in the spring. Since there is not enough light to sustain floating live plants, I place a small amount of floating plastic plants in the middle of the tank, no more than a diameter of 4 inches. Once the fish have been in the tank for at least three weeks, I begin the morning ritual scoop.

Every morning, approximately 15 minutes after the lights are turned on, I lift the cover from the tank. Using a shallow plastic container (the ones that are sold for storage of leftovers or sandwiches), I quickly scoop under the floating plants. You will very often find fry in your container! The fry are removed with an eyedropper and placed in another container to be reared. This is repeated every day or two, and you’ll be amazed at how often fry are captured.

If you wish to pick eggs and incubate them separately, a mop can be substituted for the Java moss or peat. Eggs are slightly less than 1 mm in size and fry require infusoria for the first few days after hatching before they are able to consume live baby brine shrimp or microworms. The fish of the A. georgiae species group can be quite prolific when attention is paid to temperature, live foods, and water changes.

If you are willing to provide the cool conditions required, a wide variety of small live food, and frequent, small partial water changes, you will find that these jewels will become an admirable addition to your hobby.

 
Works Cited

Brosset, A. 1982. “Le peuplement de Cyprinodontés du bassin de l’Ivindo, Gabon.” Terre Vie 36(2):233–292.

Brosset, A., and D. Lachaise. 1995. “Evolution as a lottery conflicting with evolution via sexual selection in African rainforest-dwelling killifishes (Cyprinodontidae, Rivulinae, Diapteron).” Evolutionary Biology 28:217–264.

Collier, G. E. 2006. “The genus Aphyosemion:Taxonomic History and Molecular Phylogeny.” Journal of the American Killifish Association 39(5–6):147–168.

Scheel, J. J. 1968. Rivulins of the Old World. T.F.H. Publications, Inc. Neptune City, NJ. 480 pp. (Nomenclature Note: Col. J. J. Scheel first used the term “species groups” to explain sets of related species. In 1968, Scheel’s Rivulins of the Old World set the standard for the study of killifishes.)

See the full article on TFH Digital http://www.tfhdigital.com/tfh/201006/#pg69

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