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.
This alevin is an Austrolebias bellottii Maschwitz that hatched from peat collected in July 2013, outdoors in the vegetable garden. There we only two of them that hatched from this peat this Wednesday (April 19, 2017), but they are nearly four years “old”. Swimming well and eating allright.
This week I posted a manuscript on bioRxiv. Here is the link to it:
“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.
Yesterday I colllected Austrolebias wolterstorffi (Velasquez) eggs. I just decided to make some pictures of them, using a DinoLite USB microscope with UV (395nm) and near IR (940nm) leds. Here are the results on a fresh egg (well maybe not from the last few days) that I just put straight from the peat onto a piece of paper on my desk. The result is simple to achieve and really encouraging. So I will try to get pictures of all main developmental stages with this lighting. Left: UV; Right: IR.
The coldest days seem to be over now. This picture is from last week. In my barn, most tanks still hold fish. This man is over a year old now, it’s an elongatus “Gral Conesa”. It is overwintering in an unheated garden shed, that does catch some sun during the day. So far, so good.
A small A. prognathus (Salamanca), some ten days old. I have been worrying about controlling nitrate and levels of other waste products in my tanks, to maximize juvenile growth of small ambitious fish like this. In some places the tap water is really excellent, in others it’s barely acceptable which makes the level of difficulty to maintain some species very variable. I also start believing that local tap water properties really determine how many people engage in the aquarium hobby and also determine the fish species that do well and are maintained in the killifish community. Wouldn’t it be nice if we could make some things “easy” anywhere?
In many situations, replacing water when it’s almost too late can help of course, but I prefer to be ahead of things, to avoid excessive levels to build up or to “clean” the tap water. So I am moving away from tanks with just some peat on the bottom, and I add zeolite now, just a little, to see how it behaves, what the effects are and if it might help to make raising fish easier everywhere. Plans are to measure lots of tanks and different waste product treatments later, in a situation where I start from dechlorinated tap water. Will be some work: all samples will have to be filtered and frozen before they can all be analysed together.
This afternoon I made pictures of one male and three females of Austrolebias charrua (Los Naranjales). They’ve been outside for almost three months now, and I’m happy to see they do well. Charrua is a real beauty and always a pleasure to find in your net in the field. There is quite a bit of colour variation, even between different generations of the same line. The flanks can be gold or grey, it is unclear to me what would cause that. Females can vary quite a bit in colour pattern, even on the fins. It often happens that I mistake a female for a young male.