I don’t know if it is very easy to spot, but on this photograph an egg with a developed embryo. You can see its right eye and it’s an Austrolebias charrua (“Canal Andreoni”) from peat collected in June 2018. Particular about this embryo is that it overwintered without heating, in a box with peat standing next to the cold tanks. It has been at temperatures as low as 4C, maybe even 2C. I will try to convince it to hatch in April, when night temperatures in the garden house rise above 10C.
Things break down. Fortunately, this type of small incubator usually does so in the same way: its Peltier element that cools and heats dies. The repair costs a few euros and takes less than an hour. So by now, the incubator is filled again with eggs of several killifish species and fry in their first week after hatching. As it is springtime, I am germinating chillies in it too.
A new incubation trick: I cut slices from a block of floral foam and push small depressions in them, the size of a coin and about 1 cm deep. These pits are filled with cocopeat, from the container where my killies have been laying eggs. I drip some rainwater on the foam to keep it wet, and I also cut a thin lid. Eat pit gets four fresh eggs on top of the cocopeat, to be incubated. Then the wafer goes into a 250ml plastic container for storage and to avoid desiccation. Here some A. wolterstorffi eggs after one month of storage. The white patch is fungus: I lost one egg out of the four in this pit. As you might notice, the other three contain well-developing embryos. The scratches around the pit are from stabilizing my usb microscope on the foam.
This afternoon I checked a small sample of A. wolterstorffi (Velasquez) eggs, which I photograph regularly. In a few embryos, the developing heads and eyes can be seen. In this egg, the two darkers dots above the yolk droplet are the eyes. USB-camera, near IR light. I also made a short video, where you can see that there is a heartbeat.
In 2005 I received eggs of A. elongatus “Ezeiza” incubated in Sphagnum magellanicum and eggs of A. vandenbergi “Talon Cansado” in the same material last year. I decided to give this spawning material some extra attention and offered it to fish as spawning material. For one of the samples collected like this and currently seven months old, I tried to determine the state the embryos were in. To my surprise, that was very easy! After some drying, eggs started rolling out of the moss. For example, the one on the photograph, which is A. cheradophilus “La Paloma”. Will definitely experiment with this spawning substrate further!
Some peats are just so packed with eggs you can’t miss them. This one we’re drying out a bit for an experiment at Foljuif. It’s has been filled with eggs by a group of Austrolebias gymnoventris “Castillos”. If you zoom in, you can see eggs that are still clear, in at least one other you can see the embryo’s eye. We take care that these don’t die while drying the peat.
For a few years now, I hatch my fry during winter in a small incubator with a Peltier element, kept at 22 degrees inside. It works really well, so that I even leave the fish in for a few weeks while they are fed with Daphnia and Artemia. So the fry swim in between other boxes and bags with eggs in a moderate amount of light. These boxes and bags around them are the really crucial ones at times. When I store peat on the shelves in the room or garden, hatching becomes less predictable than when I store the eggs in an incubator. So I try to behave in a safe manner now and store – per line – one box with lots of eggs in an incubator. I need to hatch it then after some four to five months. I tried to maintain lines just on the basis of boxes stored at less controlled temperatures, but that turns out to be tricky sometimes and with some risk if eggs need to be stored for long. Some additional certainty is comforting and the incubator as a back-up is taking little space. In there now, swimming happily: A. viarius (Valisas).
I just started a trial for another heating method to store my Austrolebias eggs through winter. I tacked IR heating foil to the ceiling, right above the cupboard on which I store my eggs. Contrary to heating cables I tried before, the foil doesn’t become very hot. The heat radiates well. Previous years, I used to put heated aquaria in between my peat boxes but the warmth never distributed well. My first impression is that this new thing will work better. Soon more on this with the data from the logger I put with the eggs.
All through winter, I continue to collect eggs from old boxes. Many of them have been stored at 22 degrees or at fluctuating temperatures for several years. Some contain many eggs still, many few. These few eggs are sometimes essential not to loose a line. In the picture, two eggs of A. cinereus, from a peat collected in october 2010. Picture taken today. They will be stored in a small bag during four months at 22 degrees. Then wetted 🙂
After some serious thinking I decided to try a heating mat and a controller, to store my killifish eggs at a more or less fixed temperature at home. It didn’t work. The fluctuations in temperature right above the mat for example went from 24 to 36 degrees, when I just wanted 22 C… So now I’m back to a system where some tanks with an aquarium heater are standing amidst the boxes with peat. Should work, has done so for years.