My experiences in the search for Nothobranchius in Kenya and Tanzania
Since I flew to Kenya for the first time in 1995, I could gain some experience during 13 fishing trips to Kenya and 8 to Tanzania in East Africa. There are several (almost 100%) fixed parameters to consider. - Catch times consider, the smaller species like eggersi, palmqvisti, janpapi etc. are mostly at the end of the season hardly to no longer present in the biotope. The same is true for the predators (hunters) like Paranothobranchius ocellatus and Nothobranchius microlebis, which can be caught mainly in good condition and numbers until the middle of the rainy season, usually they are more fast-moving than the other syntopic species and when the prey becomes less, or the next bigger species have become too big, they start to starve. In all biotopes where Predator and small species occur syntopically, there is a dominant species present in the region. From southern Kenya to Tanzania to the Rufiji River this is the Nothobranchius melansopilus species group (kwalensis, prognathus, melanospilus or lucius) or north from Malindi Nothobranchius jubbi. For these species, the rule of thumb is that if you find a biotope where you catch Nothobranchius, then at least one of the species is always dominantly present, Predator or smaller other syntopic species are then additions. - The temperature in the water, the extremely high temperatures that are often stated in connection with Nothobranchius, I can not confirm so. Especially at the beginning of the rainy season, when the waters are still very wide and deep, the temperatures are rather normal of about 23 - 26 °C. The deeper the lower, in the shore area where it is mostly shallower and the sunlight (if it breaks through the clouds during the rainy season) warms it up, they can be higher. The more the rainy season turns into the beginning of the dry season, the more the water volume and depth decreases, the solar radiation increases strongly, this gradually increases the water temperature. Now not only the first 5 cm of the water layer can reach over 30°C. Now the metabolism of the fish increases, the space and food decreases, which causes the fish to age and die faster. - The sea level of the found biotopes, with the number of found biotopes with Nothobranchius species, I have recorded with my GPS not only the coordinates, but also always how high above sea level the biotope is, and I could clearly determine that species occur only in a certain altitude range. For example Nothobranchius melanospilus up to about 100 m, the closely related sister species Nothobranchius prognathus from about 400 m on. - The substrate and water color, when looking for biotopes that are populated with Nothobranchius, it is very helpful to note that on red soil (laterite soil) has never been caught a Nothobranchius, because this substrate stores too little moisture for the Nothobranchius eggs laid there to survive the dry season. In these biotopes usually only tadpoles of frogs, Triops and fairy crayfish live. Possibly still washed in fish species such as Enteromius or Oreochromis from nearby rivers. These waters usually have lower levels of dissolved hardness and lower pH. Nothobranchius live on a yellowish substrate (clay-solution mixture with organic residues) that forms a deep fine silt layer in the biotope and is baked like concrete in the dry season and holds moisture well within. Also Polypterus - lungfish often live syntopically with them in the water body and survive the dry season deep in the bottom in slime capsules. Color also plays a role, so the waters are usually yellowish turbid, due to the bottom substrate. It is still puzzled why the waters are constantly yellowish turbid, because the turbidity does not sink. Water that is left in a bottle or tub becomes clear over time as the turbidity sinks. The two most consistent theories, which probably complement each other, are that the temperature differences cause water circulation, which also explains the oxygen balance in the deeper water layers. Secondly, that the fish living there keep stirring up the fine turbid matter (which is a bit difficult at the beginning, because the young fish are still too small). I have not been able to catch any Nothobranchius in clear waters, although Nothobranchius robustus have been caught in clear reed swamps around Lake Victoria. - Seasonal changes dry season to wet season, note the not only distribution limits but also hydographic systems and length and number of rainy periods. Do we have in the central coastal area of Kenya to Tanzania in the south a long rainy period in March to May and a short one from late November to early January. Strikingly to the north (northern Kenya and Somalia) and to the south on the coast (southernmost Tanzania and Mozambique) the length of the dry season increases, and usually only one major rainy period). Also the higher located hinterland, or countries in central Africa can have different rainy seasons. Of course, this must be taken into account when breeding. Species from southern Kenya and Tanzania are usually ready for watering after 8 - 12 weeks, Nothobranchius rachovii at the earliest after about 4 months, this also depends on the storage temperature of the eggs in peat. The cooler the longer the laying time, if the temperature is too low, the eggs cannot even change to the next diapause, or they die. Du hast Folgendes gesendet: - Syntopic distribution of species, the highest number of species is in coastal Kenya and Tanzania. This also includes the highest number of syntopic species in one biotope. In Kenya so far 3 species could be detected in one biotope (I personally caught Nothobranchius kwalensis and palmqvisti in the south, and Nothobranchius jubbi and microlebis in the north), in Tanzania there were 5 species in one biotope until 2009 (I was able to detect in the inflow of the Rufiji River in 2005) and in 2010 I was the only one who was able to detect 6 species in the inflow of the Ruvu River (Paranothobranchius ocellatus, Nothobranchius melanospilus, janpapi, flammicomantis, eggersi and annectens) = location FTZ 2010-21, Mwakanga. To the north and south, and from the coastal lowlands to the higher inland plateau and other Central African countries, the number of syntopic species decreases. The distribution of the species is often also in the inflow of the rivers, or their tributaries. This can also lead to the fact that in the rainy season, in nearby biotopes in the entrance of rivers often also non-seasonal species, such as shining-eye fish, cichlids, tetras, barbs, catfishes, etc. migrate, and with receding water levels in the ponds and swamps are isolated and then die when the biotope dries up. It is always very interesting for me to discover new biotopes (possibly new only for me) and the species living in them. For example, I was the first to detect Nothobranchius eggersi south of the Rufiji River in 2005. This always makes it exciting, possibly not only to discover new species but also to add new distribution limits. - Water parmeter, here's some data on sites: FTZ 2009-3, Chekelei south (Nothobranchius vosseleri) microsiemens 437, ppm 223, pH 6.53, temperature 25.6°C, 390 m sea level- Pangani River inlet. FTZ 2009-12, Sangue (Nothobranchius attenboroughi) Microsiemens 130, ppm 64, pH 6.75, temperature 21°C, 1239 m sea level - Lake Victoria Area, Serengeti FTZ 2009-16, Kintiku (Nothobranchius neumanni) microsiemens 258, pH 7.23, temperature 22.5°C, 844 m sea level- Bahi Swamps FTZ 2009-18, 4 km W Magole (Nothobranchius prognathus) Microsiemens 716, pH 6.95, temperature 25.2°C, 402 m sea level- Wami River Inlet FTZ 2009-20, Vigwaza (Nothobranchius melansopilus, spec., janpapi) Microsiemens 111, pH 6.52, temperature 29°C, 92 m sea level - Ruvu River inflow FTZ 2009-23, 800 m NW Bagamoyo (Nothobranchius melanospilus, janpapi and spec.) Microsiemens not measurable - too salty, 5 m above sea level, Ruvu River inflow. © Steffen Fick
Steffen Fick.