Returning fish to the shed now that cold weather approaches, this trio of Austrolebias reicherti (Paso del Dragon) appears. They are about eight months old. For a while, I had a line from the same location where the males had a more pronounced blue hue. We managed to karyotype one of them and it turned out to be a triploid. Whether that was the cause of the colour difference we observed or not could be answered by karyotyping a bunch of wild-caught fish with colour differences. Karyotyping can be done by fin-clipping and a recapture where the regenerating fin is sampled, no fish would have to be sacrificed for this test.
I’ve been slow with most hatching this year, for various reasons. Therefore I need to catch up a bit right now. Often at home, it seemed a good idea to have the alevins right in front of me for a while. So I hatched them on a shelve in between vanilla cuttings and my favourite teas, with rain water. When they are a few days old, most alevins will go to the garden where it cools well at night. There currently are A. elongatus, bellottii, luteoflammulatus, univentripinnis, gymnoventris and wolterstorffi swimming in the kitchen.
After some years without them, I’ve started breeding Austrolebias gymnoventris “Salamanca” again. The pairs I have now have been very prolific. What I like about this species are the dark body colour they can get and the beautiful contrasting spots on their anal fin in particular. They can deal with high temperatures, but the water needs to be clean and with little nitrates.
Time to get going again. The first juveniles are in the garden already, and other batches are getting ready to go as well. I’m hatching some five to ten lines per month now. Not that all tanks are empty. On the contrary, species that made it through winter this year without heating are A. melanoorus (“R5km399”), nigripinnis (“Franquia”), charrua (“Canal Andreoni”), paucisquama (“Sao Sepe”), vazferreirai (R44km44), Cynopoecilus melanotaenia (“Paso del Dragon”), bellottii (“Maschwitz”), duraznensis (“Paso San Borja”) and the man on the photograph. He’s a luteoflammulatus (“R9km205”). Unfortunately the female in the same tank didn’t make it, but they were laying eggs until December. Christmas eggs.
This is how I grow fish at home during winter. They are hatched in a small Peltier incubator, and kept in there for a few days with Artemia as the main feed.
After that they are transferred to relatively flat boxes with tap water, rain water and java moss. The food then becomes a mix of Artemia, Daphnia, copepods and tubifex or blackworm. Great at that point is that mortality can be almost avoided completely if the tanks are not crowded. You should count an Austrolebias alevin from a small species per 150 square centimeter tank surface. For large species, count two to three times that surface.
At these low densities, the fish will grow to maturity without problem. In the stack: Cynopoecilus melanotaenia (Paso del Dragon), Austrolebias charrua (Canal Andreoni), Austrolebias patriciae (Cruce Ferrocaril), Austrolebias vandenbergi (Talon Cansado), Austrolebias reicherti (Paso del Dragon), Austrolebias luteoflammulatus (Ruta 15km7.5, Canal Andreoni), Austrolebias gymnoventris (Velasquez).
Adults of A. melanoorus “R5KM399”. I collected them today, November 17, to move them inside into a 40 liter aquarium. The fish have been out since June. In this species, I particularly like the patterns of spots and lines on the fins of the males and the bar through the eyes.The females often have blobs on the flank, variable in size and number.
There are 15 more tanks outside to check and move. No frost foreseen yet.
A pair of relatively young Austrolebias vazferreirai (R44km44) from the type locality. They lay very well and are little aggressive. The water in their tank has some clay added and is therefore turbid. Note the dot on the flank in the male and the weaved pattern. Often vazferreirai males look just grey.
I didn’t expect her to be still alive but here she is. A female A. wolterstorffi (Velasquez) that overwintered at temperatures going as low as 4C. A pair of the same population managed to lay eggs all through winter. I lost them in March when the water started warming and I just hatched about fifty of their alevins yesterday.
“A case for sympatric speciation by cannibalism in South-American annual killifish (Austrolebias)”
We demonstrate that large Austrolebias evolved at least three times from small ones. For one case, we argue that piscivory evolved starting from the evolution of cannibalism on conspecifics.