I’m experimenting with cultures that I can basically pour into the fish tank entirely, once “mature”. The culture I mean. For now I’m trying things in 0.5 glass jars at home on a shelve with moderate daylight. I’ve added tap water, a few Daphnia and small detritus worms that I scooped from a rainwater drum in my garden. On the bottom there are some specks of cocopeat and I fed the system a few times with dried yeast. So far, the Daphnia multiply, the worms too, the yeast seems to persist. Things go well. One jar had a solution with some drops of coffee creamer standing in it for a week before the water was replaced and the other animals were added. The cream had created a film on the glass in which the worms indulge. Next challenge: Massively increase the surface where the film can settle which hopefully increases the worm fraction. The nice thing about that is that I won’t pour the surface covered with film into the fish tanks with the feed. On the photo: few of the worms. If you magnify them a bit, you can see their chaetae.
The last few weeks I hatched fry from several species. In some cases, there are lots. Due to space limitations, I decided to put a few groups outdoors. Before that, they were fed twice with Artemia. Then they were put in 70 liter tanks with a stock of invertebrates that I fished and sieved from a ditch. Things seems to go great! There are some casualties of course, as the photo shows, but overall everything goes well and the fry even seem to grow faster than ever. The fry are from Austrolebias prognathus “Salamanca”, and charrua “Ruta1316”. If all goes well, I might do this more systematically.
More on the experiment done in the ECOLAB. The results indicate that hatching does not depend in a simple and obvious manner on the temperature pattern. What the data do suggest is that the proportion of alevins which swim well and which are still alive after two weeks is largest, when water is added at the lowest temperature in the cycle, so that it increases steadily for 12 hours after wetting.
Last week, at the ECOTRON Ile de France research station, five students, one engineer and myself did a short experiment on hatching Austrolebias. We used a prototype of the ECOLAB developed there, to simulate a diurnal cycle with a ten degree temperature difference between night and day (going from 15 to 25 degrees). At four times during the cycle, we put embryos in the ECOLAB in multiwell plates and added 5 ml of “hatching water” to each well. We used about 400 embryos from several species.
The data will be analysed next Tuesday, but my first impression was that we had the least bellysliders when the embryos were wetted at 15 degrees, and the temperature went up to 20 degrees within the following six hours.
The ECOLAB consumes lots of energy and resources, so let’s hope our results pay off, that the outcome will make all our hatching more efficient. More on this next week.