Nothobranchius, commonly known as notho killifish, belongs to the family Nothobranchiidae within the order Cyprinodontiformes. These vibrant African freshwater fish are some of the most brilliantly colored species found in aquariums, captivating enthusiasts with their striking hues.
One of the most distinctive features of notho killifish is their unique lifecycle, which is intricately tied to the arrival of the rainy season. During this period, they thrive in temporary water bodies that form after rainfall. Their eggs are adapted to survive dry spells, lying dormant in the substrate until the rains return, ensuring the continuation of their species.
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Habitat in the wild
According to various estimates, the genus Nothobranchiidae includes between 30 to 60 species of notho killifish that inhabit the waters of Africa. This wide range is largely due to the numerous color variations found in the wild, with new interspecies hybrids occasionally reported in the literature.
The notho killifish habitat spans nearly the entire continent of Africa. Confirmed locations for Nothobranchius species include the northern and southern regions of South Africa, areas in Namibia, Zambia, southeastern Democratic Republic of the Congo, southeastern Zimbabwe, Malawi, Mozambique, Tanzania, Kenya, Uganda, Somalia, southeastern and southwestern Ethiopia, southern Sudan, South Sudan, southern Chad, and northern Cameroon.
While some species are restricted to habitats covering just a few square kilometers, others occupy extensive areas. Nothobranchius have adapted to thrive in nearly all types of water bodies, making them resilient fish.
Tanzania is particularly rich in notho killifish diversity, with more than one-third of all known species found within its borders. The country has historically been a significant source of new fish species, many of which have been introduced to aquarists worldwide.
The habitats of notho killifish are often situated in hard-to-reach areas, with relatively dense populations frequently isolated from one another across vast territories. This isolation contributes to the emergence of diverse color variations, ranging from subtle differences to stark contrasts among individuals of the same genus.
Typically, notho killifish thrive in small, shallow, standing waters, which can often be as humble as puddles, drainage areas, or bogs located in river floodplains, although not directly connected to them. These bodies of water can be separated by dozens of kilometers.
During the wet season, these habitats are replenished with water, only to dry up under the intense African sun during the dry season. The water temperature in these ponds tends to remain stable throughout the ongoing season, ranging from 20 to 24°C during the rainy season and climbing to between 28 and 35°C during the dry season.
The bottom of these ponds typically features a soft substrate of muddy sand with a high content of organic matter rich in humic compounds, resulting in an acidic pH level and low mineralization.
Nothobranchius exhibit fascinating behaviors during breeding, with males often engaging in elaborate courtship displays to attract females. The vibrant colors and patterns that they display play a crucial role in these rituals, as they signal fitness and genetic quality to potential mates.
While fish species living in rivers may migrate to deeper perennial waters during dry spells, notho killifish inhabiting ephemeral bodies of water face significant challenges, as most of them perish when their temporary homes dry up. In a literal sense, notho killifish are seasonal fish, tied to the rhythms of the African wet and dry seasons.
Moreover, many Nothobranchius species are considered vulnerable due to habitat destruction and climate change. The loss of their natural habitats, primarily caused by agriculture, urbanization, and climate variability, threatens their populations. Conservation efforts are essential to protect these unique species and their ecosystems, ensuring that future generations can appreciate their beauty and ecological significance.
Eggs made of mud
As a result of evolution, notho killifish have developed a unique survival mechanism that is closely linked to the rainy season. One of their main peculiarities is their unusual lifecycle, which is finely tuned to the unpredictable weather patterns of their African habitats.
When the first raindrops fall after a prolonged dry season, beautiful notho killifish emerge in almost every puddle. They grow rapidly, and just a few months later, they are ready to breed. This urgent need to reproduce is driven by their ephemeral habitats, where water can vanish as quickly as it arrives.
To ensure the continuation of their species, notho killifish lay eggs as soon as possible while their ponds still contain water. Remarkably, their eggs are incredibly resilient and can enter a dormant state, often referred to as a hibernation period. During this dormancy, the eggs can survive without water for up to six months or even a year, depending on environmental conditions.
The duration of the eggs’ dormancy is influenced by factors such as humidity and surrounding air temperature. This adaptation allows the eggs to withstand climatic disturbances, such as prolonged droughts. For instance, in some regions of Sudan, heavy rainfall may occur only once every four to five years. The critical factors determining the length of the dormancy period are the temperature and humidity of the substrate where the eggs are buried.
Notho killifish Types
Bluefin notho (Nothobranchius rachovii)
Nothobranchius rachovii, commonly known as the bluefin notho killifish, is one of the most fascinating and vividly colored representatives of its genus. However, it is important to note that the stunning coloration described applies primarily to the males.
This species inhabits the Zambezi and Pangve River basins in Mozambique, as well as waters in northeastern Africa. In the wild, male Nothobranchius rachovii typically reach a length of about 8 cm, while females are noticeably smaller and less colorful.
The males are particularly striking, displaying a brick-red body that transitions to a beautiful light blue near the tail fin. This vibrant coloration makes them a favorite among aquarists and enthusiasts, who appreciate their visual appeal and dynamic presence in home aquariums.
Gunther’s Killifish (Nothobranchius guentheri)
Nothobranchius guentheri, often referred to as the red-spotted notho killifish, inhabits the ephemeral waters of Kenya, Tanzania, and Mozambique. In aquarium settings, this species typically grows to a length of about 7 to 8 cm.
The body color of Nothobranchius guentheri is primarily light blue or greenish, adorned with numerous red spots and lines that become more pronounced near the tail. The pectoral and abdominal fins are also light blue, while the anal and dorsal fins showcase a striking dark red that gradually transitions to blue. The tail fin is distinguished by its black outer edges, adding to its visual appeal.
In contrast, the females of this species exhibit a more subdued appearance, featuring light brown coloring and transparent fins. This dimorphism not only highlights the males’ vibrant coloration but also plays a role in their breeding behavior.
Egger’s Killifish (Nothobranchius eggersi)
Nothobranchius eggersi is a small but striking species known for its large, wide fins. The anal and dorsal fins are positioned closer to the tail, creating a fan-like appearance that adds to their allure.
What truly captures attention, however, is their vibrant coloration. In the aquarium trade, Nothobranchius eggersi is often available in various forms labeled as “red” and “blue.” These two primary colors are always present in their coloration, with one typically being more dominant than the other.
Keeping in a tank
Nothobranchius species are highly regarded among aquarists due to their unpretentiousness regarding tank conditions. Most notho killifish do not require extremely soft or acidic water, making them well-suited for a variety of setups. In fact, they thrive in tap water, which simplifies tank preparation for both keeping and breeding these vibrant fish.
Tank Size and Conditions
Due to their small size, Nothobranchius do not need large-capacity tanks. A minimum of 2-3 liters of water per fish is sufficient, and total tank capacity can range from just 10 to 15 liters. This makes them an excellent choice for beginner aquarists or those who prefer nano tanks.
While keeping Nothobranchius is generally straightforward, ensuring the survival of multiple generations requires creating optimal tank conditions. In the wild, these fish live in temperatures ranging from 16 to 32°C, with a daily temperature variation of up to 6°C. In captivity, the ideal temperature for Nothobranchius is between 20 and 23°C. Lower temperatures can cause males’ vibrant coloring to fade, while higher temperatures may shorten their already limited lifespan.
The water hardness (dGH) should range from 5 to 20°, and the pH should be maintained between 6 and 7.5. Maintaining a clean tank and performing weekly water changes is essential for their health.
Water Change Guidelines
However, it’s best to avoid making drastic changes to the water all at once; instead, gradually replace water to ensure the new water closely matches the old in terms of chemical composition. This gradual approach can enhance the fish’s appetite and overall health. For instance, performing water changes in smaller portions rather than all at once can help prevent stress and ensure that the fish acclimate more comfortably to any changes in their environment.
Some species of Nothobranchius may react negatively to sudden shifts in water chemistry, which can lead to a decline in health or even death. Thus, maintaining stable water parameters is crucial for their longevity and well-being.
Lighting and Plant Selection
Since Nothobranchius prefer dim lighting, consider using floating plants to diffuse bright light. When selecting tank plants, choose those that thrive in lower light conditions, such as Java moss, Christmas moss, Java fern, and various species of cryptocoryne.
These plants not only provide essential hiding spots for the fish but also help maintain water quality by absorbing excess nutrients. A densely planted tank with appropriate lighting can create a more natural and comfortable environment, allowing Nothobranchius to display their vibrant colors and behaviors.
Optimal Conditions for Vibrant Coloration
The appearance of Nothobranchius is most spectacular in a densely planted tank at a temperature of 21 to 24°C. Under these conditions, males can reach their maximum size and achieve their brightest coloration. Providing the right combination of temperature, plant life, and light will enhance the overall beauty of these fish, making them a stunning centerpiece in any aquarium.
Lifespan and Care Considerations
While Nothobranchius typically live for only about six months in the wild, some species can thrive in captivity for up to three years when provided with the right care. Their lifespan in captivity can be influenced by factors such as water quality, temperature stability, and overall care.
By ensuring optimal conditions—such as consistent water parameters, appropriate tank mates, and suitable plant life—aquarists can significantly extend the lifespan of their Nothobranchius, allowing them to enjoy the vibrant beauty of these fish for longer.
Tank mates
Creating a species-specific tank with one male and three to four females is the best approach for keeping notho killifish. This setup minimizes aggression among males, fostering a peaceful environment for breeding and display. In a mixed-gender tank, multiple males may engage in territorial disputes to attract females. While these encounters can lead to minor fin damage, such injuries are typically not serious and heal quickly. When no females are present, males tend to exhibit calmer behavior, reducing the chances of conflict.
For those interested in community tank setups, other small fish species can coexist well with Nothobranchius. Suitable tank mates include various types of killifish, Endler’s guppy, guppy, and pygmy corydoras. These fish share similar care requirements and temperaments, contributing to a harmonious aquatic environment. However, avoid housing Nothobranchius with long-finned species, as these fish may nip at the delicate fins of notho killifish, leading to stress and injury. Selecting appropriate tank mates is crucial for maintaining the health and well-being of all fish in the aquarium.
By carefully considering tank setups and compatible species, aquarists can create a thriving environment for notho killifish. This approach allows these vibrant fish to exhibit their beautiful colors and natural behaviors while minimizing stress and aggression among tank inhabitants. Additionally, male notho killifish often engage in elaborate displays of color and fin positioning during courtship, which can be fascinating to observe and adds to the visual appeal of the aquarium.
Feeding
Notho killifish have a relatively intense metabolism, which necessitates regular feeding. It’s best to provide them with small portions of food twice a day, ensuring they can consume everything within a few minutes. In their natural habitat, notho killifish primarily feed on small, spineless organisms. In captivity, their diet can include a variety of food options, such as live, frozen, or high-quality artificial foods.
However, it’s worth noting that some notho killifish may be picky eaters and might refuse to eat artificial food altogether. To promote optimal health and vibrant coloration, it’s important to observe their feeding preferences and adjust their diet accordingly, ensuring they receive a well-rounded nutrition plan.
In addition to their preferred diet, notho killifish may display hunting behavior when live food is introduced, showcasing their natural instincts. This can be particularly entertaining for aquarists, as they may dart and chase after the food, highlighting their active nature.
A varied diet rich in proteins can help enhance their color and promote healthy growth. Different species of notho killifish may have specific dietary requirements, so it is crucial for aquarists to research the particular needs of the species they keep. For instance, some may thrive on a diet heavily composed of protein, while others might benefit from a more balanced approach that includes vegetable matter.
In addition to regular meals, some aquarists provide occasional treats like daphnia or brine shrimp to enrich the fish’s diet and encourage more active behavior. These live foods not only serve as a source of nutrition but also stimulate natural hunting instincts, making feeding time more engaging for both the fish and the aquarist.
The pigments in certain live foods can significantly influence the coloration of notho killifish, making diet an essential factor for aquarists aiming to showcase these vibrant fish. For example, feeding them foods enriched with carotenoids can enhance the red and orange hues in their bodies, providing a more striking appearance.
Gender differences: male vs female
The notho killifish exhibits pronounced sexual dimorphism, making it easy to distinguish between males and females. Males are notably larger and more vibrantly colored than their female counterparts. They display an array of vivid hues, well-defined patterns, and a wide color palette that includes surprisingly unexpected combinations. These bright colors not only enhance their visual appeal but also play a crucial role in mating displays, as males often showcase their vibrant patterns to attract females. During breeding seasons, male notho killifish engage in elaborate courtship rituals, displaying their fins and colors prominently to entice potential mates. This captivating dance can be a fascinating sight for aquarists.
In contrast, females possess a more subdued appearance. Their coloring typically consists of a filbert-brown palette, which lacks the bright glow and intricate patterns found in males. The absence of vibrant coloration in females serves as a natural adaptation, providing them with better camouflage in their natural habitats. This coloration helps them blend into their surroundings, offering some protection from predators while they care for their eggs. The muted colors of female notho killifish not only provide camouflage from predators but also play a role in their reproductive strategy. By blending into their surroundings, females can more effectively guard their eggs against potential threats.
Breeding
Breeding notho killifish is generally straightforward, with females capable of laying eggs as early as 1.5 to 2 months of age, often producing new eggs daily, even in a community tank setting. However, successfully saving the eggs and ensuring they develop into juveniles can be more challenging.
To facilitate breeding, a spawning tank of about 5 to 10 liters is recommended. The ideal substrate for both spawning and egg incubation is peat, applied as a 1 cm thick layer. Peat is advantageous because it retains moisture effectively and possesses antibacterial properties. To prepare the peat for use, it should be boiled for 20 minutes, thoroughly washed until the water is clear, boiled again for an additional 40 minutes, and washed once more. This preparation helps maintain a neutral pH, preventing the substrate from acidifying the tank water.
Nothobranchius can breed successfully in both soft and hard water, although the water pH should not drop below 6.5. Remarkably, they can thrive even in very hard (dGH 20°, KH 22°) and alkaline (pH 8) water conditions. The quality of the tank water is critical; it should be free of organic materials, such as uneaten food and waste, as these can be detrimental to the eggs’ survival.
Once the eggs are laid, the breeding pair typically separates, with females laying anywhere from several to dozens of eggs depending on the species. Most notho killifish species are prolific, with females capable of producing 150 to 200 eggs or more throughout the breeding cycle.
The incubation time for the eggs is influenced by both the substrate temperature and humidity. If the peat is overly dry, the incubation time may significantly increase. A slight increase in temperature and a diurnal variability can reduce the dormancy period. It is generally accepted that if the peat containing the eggs is kept at temperatures between 27 and 29°C, the eggs can be submerged in water after about six weeks. In cooler conditions, this may take two months or longer.
Regular checks of the eggs are essential, allowing for the removal of any damaged ones. The incubation period can last anywhere from one month to a year. When inspecting the eggs with a magnifying glass, if the embryonic eyes exhibit a silvery tint, it is time to transfer the peat with the eggs into a tank with a water depth not exceeding 3 cm.
At hatching, the juveniles are quite small; however, they can feed on brine shrimp nauplii almost immediately, which simplifies the feeding process for aquarists. For those species of notho killifish with exceptionally small juvenile sizes, rotifers or slipper animalcules are recommended as initial food sources.
Juveniles experience rapid growth, reaching adult coloration and reproductive maturity in just 1.5 to 2 months. This swift development is crucial, as the short rainy season requires them to grow quickly and reproduce within a limited timeframe.