Austrolebias charrua

Austrolebias charrua (Los Naranjales)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.

Feed the small

For a while I try to raise small fish without much Artemia. It decays when not eaten, it can feed predators of the fry. I’m down to two to three feedings of Artemia now, without much mortality. From day one, I add a mix of living invertebrates to the tanks, as in the video. Chaoborus larvae are removed from the mix, large Culex as well. The tank gets some tap water so that the water does not remain too soft and abundant java moss. Per day, some extra (rain) water is added and food if necessary. For this extensive setup, population density is critical: the tank surface per individual should be some 100 square centimeter. So for really large groups, I need to switch back to an intensive setup with water changes etcetera.

Egg drop out

A. cheradophilus (La Paloma 2016)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!

Lots of eggs

A. gymnoventris eggs (2016)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.

Worm action shots


Not easy to get decent pictures of detritus worms while they move around in my jar cultures. Here a collage of a rear end and a front end. The pictures were made with a dinolite USB microscope. All the small specks in the pictures are alive as well. Will need to use a different setup to photograph these, probably a water droplet, and a lot of patience.

Winter hatches

Winter, incubator (2016)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).

0.5 L Culture

Jar culture (2016)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.

Winter guests

A. gymnoventris (2016)During winter, I keep a few groups of fish in the house, to make sure they go on breeding and to collect eggs often. The room is heated to some 15 degrees, and receives sun in the winter afternoons. In spring, by the end of April, the fish go into the garden again, or they are replaced by a bunch of more exotic ones. Here a male A. gymnoventris “Castillos” which lives in a group of some six adults. They eat well and produce eggs well. This male is some eight months old.

A vandenbergi

Austrolebias vandenbergi (2015)A picture of a pair received as A. vandenbergi (Talon Cansado), hatched end of January 2015 from eggs received from Ricardo Rojas. They look great, although I expected a more protruding snout, but it might be masked by the bulgy head older Austrolebias can get. The male does get some wear on the edges of his fins now, so I might lose him in a while. November is very warm this year and they continue to lay eggs well. The eggs are quite large for the size of these fish.