Redtail Notho (Nothobranchius guentheri)
The genus Nothobranchius is not terribly familiar to the average aquarist. Though these fishes are gorgeously colors (especially so in the males), come in a very manageable size, and are generally quite peaceful, they have one major drawback which has kept them from gaining a larger following. Nothos, as they are affectionately known among devotees, live fast and die young.
Take, for instance, Nothobranchius furzeri, a species native to certain semi-arid stretches of Mozambique and Zimbabwe. This little fish, just 2.6 inches fully grown, can go from a dormant egg to sexual maturity in a only 17 days! The full lifespan isn’t much longer, with studies from laboratory specimens showing the maximum age at less than 12 weeks. This unusually brief and rapid existence (particularly so for a vertebrate) has made the genus a model organism for researchers interested in the biological and genetic processes of aging.
Nothos are a type of killifish or toothcarp (Cyprinodontiformes), and the genus, comprised of around 75 recognized species at the moment, is restricted to Eastern Africa. The reason for their modified life history is simple enough to understand when you consider the habitats they come from. Just like with brine shrimp in a vernal forest pool, the aquatic homes of Nothobranchius are generally ephemeral in nature, located in dry habitats which receive seasonal monsoon floods.
For the Redtail Notho, this home is on the island of Zanzibar, situated just off the coast of Tanzania. It’s pools begin to fill in February and disappear by August. During this time, the fishes grow quickly on a diet of aquatic insects (primarily midge larvae) and spawn on a daily basis. Males are aggressive among themselves (which seems understandable given the pressure they’re under), and initiate mating by coaxing the females towards the soft muddy bottom to fertilize the deposited eggs. Once the waters evaporate and the fishes die off (enriching the soils in the process), the next generation waits in a suspended animation of sorts, termed a diapause. With the return of rains the following spring, the cycle continues anew.
The casual aquarists out there may wish to add this short-lived fish to a peaceful community aquarium, which will provide an almost unnatural splash of color. A single male and one or more females is recommended, unless larger accommodations are available (remember, the males really don’t care for one another). A wide range of foods are accepted, though frozen or live options are particularly relished.
For those looking for something a bit more challenging, this fish is easily bred with a bit of planning. A small aquarium, 10-20 gallons, can house a pair or trio. With a bottom of peat, eggs will be laid in the hundreds. The fish will eventually perish, and the peat and eggs can be allowed to dry out… but not too dry. Kept damp for a period of three months, the eggs will be ready to hatch and rise forth from the mud, like some sort of piscine phoenix.