There are these embryos that are refusing to hatch. Here such an environmental change denier and an alevin that did hatch (A. elongatus “Gral Conesa”). Our main explanation is that the non-hatcher will do so at another occasion and is just hedging its bets. However, here the hatched alevin suggests another explanation: it is infected by fungus. The unhatched embryo might suffer the same infection, preventing it from continuing the life history while being eaten alive.
It’s almost February, time to start raising this year’s new breeders. I’ve started at home, with bags from Uruguay and Argentina that I stored for four months (Thanks Heber Salvia, thanks Ricardo Rojas, thanks Rafael Mitre Muñoz!). The photo is the moment where I put the peat+eggs in small containers with some extra peat. I add half a cm or one cm of 15C rain water. All containers then go inside a small incubator at about 22 degrees C. Result: 23 cheradophilus “la Paloma”, some 15 vandenbergi Talon Cansado, melanoorus Tranqueras, arachan Bañado del Chuy, duraznensis Paso de san Borja, alexandri San Javier, El Bulin and El Pingo. Not bad to start the year with! Some other fish here at home will have to move soon!
Spring has advanced well, I’ve been hatching alevins wherever I could. For different reasons, I wanted photographs of freshly hatched alevins. At first I always waited until they swam well after hatching. Now I found out I can just as well photograph them while still “bellysliding” and that they will start to swim well after a while if I transfer them to a very shallow tray (or with different water levels) after taking the photo.
October. It’s getting chillier at night. I have stopped hatching in the wooden garden house. The fry that hatched in September, is still being fed with small zooplankton and some Artemia added once or twice a week. That goes fine so far. Growth rates seem OK, so that I expect them to sex out in a few weeks. Meanwhile, I am checking all my boxes with peat, to find out which ones have many eggs and which ones few. Autumn and winter are good periods to plan the coming year…
After some weeks of attempts at hatching many fry, my wooden fish house got filled up with small tanks from bottom to top. I decided to postpone further hatching for some time, until nearly all fish are outdoors and reproducing. Inside the house, there still are small groups of Austrolebias wolterstorffi (El Bagre, Canal Andreoni), prognathus (Canal Andreoni, Salamanca), elongatus (Vivorata, Villa Soriano, Gral Conesa), cheradophilus (Ruta1316), vazferreirai (R26), arachan (Chuy), gymnoventris (Castillos, Velasquez), nigripinnis (Maschwitz, San Juan Missiones), viarius (Castillos), bellotti (Maschwitz, Ezeiza), apaii (Villa Soriano), charrua (Canal Andreoni, R1316), luteoflammulatus (Canal Andreoni) and lonesome individuals of a few more species.
Suddenly I got fed up with transferring peat from a box/bag into a small tank, adding water, putting all peat back in a bag/box afterward. I now hatch the fry straight in the box where their peat is stored in. One liter or 0.5 liter plastic take-away boxes are used for storage+hatching. I buy them in a Chinese supermarket, per 50 or 100. I add rainwater from a tank to the peat in the box. After one or two days, the fry (if there are any) are poured off into a different tank. Drying the peat for the next round: I close the lid again and put the tank on its side. All water usually drips out soon. I am contemplating to construct some sort of dam-net-rake which allows me to pour of all excess water quickly.
Some species that are dead easy to raise on Artemia in a fish room, are a bit more trouble in “greened” conditions. Suddenly, I find Austrolebias nigripinnis difficult. The alevins are small, and when the temperatures are a bit low they grow relatively slowly. Meanwhile, the small pond food which I have carefully sieved out for them, has increased a lot in size. Nigripinnis gets eaten, can’t pick the food, end of story. So I definitely need to add Artemia the first week so that they don’t starve, and I will postpone hatching them to later dates, so that cold nights are not occurring anymore.
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.
I continue hatching annual killifish in small volumes of water at home, feeding the alevins with pond food. This week I wanted to hatch embryos from 9 bags with eggs which I bought on Aquabid, or otherwise. All bags came from Argentina or Uruguay. These bags are usually small and can become completely dry prematurely, killing all embryos in them. To keep the peat inside moist and the air with plenty of humidity, I used to put the bags on a sponge. This was then placed inside a plastic box with a layer of demineralized water on the bottom, keeping the air inside saturated. Disadvantage: the labels fade and bags need an extra waterproof mark. This time I checked the bags weekly and injected a few drops of water if necessary, using a syringe with a needle. This worked fine!
+ The hatching itself went like this: I added very cool water in the morning (14 degrees C), and let the temperature rise in the room during the day (to over 23). The amount of bellysliders was minimal.
Swimming are: A. luteoflammulatus, reicherti, elongatus, cheradophilus, nigripinnis, arachan. The week started well…