This website has been down for a number of months. It had been hacked and blocked, but that is all fixed now. Meanwhile much has changed around me. I will resume fieldwork in South-America with colleagues from Chile, Argentina and Uruguay. A first model to predict killifish population dynamics is being debugged. The fish are done with overwintering. See you all soon!


Some boxes with peat on my shelves have been there for years. It is always difficult to know how many eggs are actually in one, and I would like it if all that peat could take up a little less space. So I’ve decided to attack the problem at the root, and “concentrate” a peat before it gets stored. When I collect it from a tank with breeders, it is poured into a round container from which you can pour off the water and particles at the surface easily. That mix goes into a shallow tray, so that any eggs spilled out can be recovered. The mix from the tray is poured over a net, the water added to the bowl again and the procedure repeated. The peat in the net is supposed to be relatively egg-free and can be discarded or dried and re-used. If the peat contains any eggs, they make up an increasing fraction of the peat remaining in the bowl.


On the first of October, a Brazilian newspaper article probably made the hearts of many killifish breeders miss a few beats. The Brazilian federal police, with the support of several institutions, did searches in several places after some 37 parcels with killifish eggs had been seized at five locations where they were sent from. The Federal Police claims to launch 12 police inquiries in the countries of destination of the mail orders (US, Germany, Bulgaria, Malaysia, Hungary, Russia, Ecuador, Czech Republic, China, Great Britain, Argentina and Scotland) to investigate the alleged smuggling and environmental crime. In the searches, several aquariums were found in the homes of some involved, containing hundreds of fish (the system looked really good by the way) and eggs.

These are the facts. Then there are the accusations. An aquarium staff member is accused of “biopirataria” and the recipients of the mail orders are claimed to be researchers and collectors. What that means is unclear. Whether these researchers research anything to do with killifish is unclear. I read this as an incrimination, without evidence that it has anything to add next to the fact that export legislation has not been followed and maintenance permits were not present. It seems destined to reinforce the claim of biopiracy, which is outrageous. I am certain the recipients have no other intentions than to breed and share their killifish further and that there is no transfer of public knowledge into private hands. If the involved researchers produce new knowledge based on their (illegal) material, the benefits will be open to all. That’s how it works. I don’t know of any industry interested in patenting or commercializing killifish species.

What I really dislike is that a killifish breeder and apparently “trader” is almost depicted as a drug producer and trafficker. I don’t want to dispute the relevance of nature protection laws at all but see little benefit in this whole operation next to pointing out that some phenomena are illegal. Illegal does not mean unethical. Disturbing is that there is no mention of what happened to the living material confiscated. Are the fish allowed to complete their life cycles, will the eggs develop and contribute to a next generation? Does their natural environment still exist, since the time when the ancestors of the eggs were captured? How many generations have been bred already by the enthusiast outlaws before these eggs were shared?

In replies and a poll circulating, the discourse is present that killifish have been regularly saved from a single or a few ponds where they occurred before these were destroyed. I propose that when natural habitat is destroyed in a country or destined to be destroyed soon, that from then on anyone can keep and trade the animals specific to that habitat freely. This is a principle, and I am not going to work out the legal consequences. The idea is just that when a state does not take it’s responsibility for a natural population or a species, that we still can if we want to.

Straight from the bag

Tonight I hatched two bags that had arrived from Argentina four months ago. At arrival, the eggs were in sealed bags completely filled with peat and sphagnum and with visibly many eggs. If the sealing would hold tight during incubation, there might be a risk that oxygen might lack at some point, while low oxygen is no problem for fresh eggs and can help to store them for longer. I cut off a small corner of each bag and placed them separately within a larger ziploc bag. This seemed the best way to avoid desiccation, while allowing oxygen in. Here’s the result. Two very successful hatches, one of Austrolebias bellotti, the other of Austrolebias elongatus. Both from Ezeiza. PS: They were hatched in 1cm of water and there was one bellyslider. I am planning to cut corners like this more systematically.

Desiccation effects in A. bellottii

VanDoorenVarelaFig1Another manuscript out in the open:

“Desiccation plasticity and diapause in the Argentinian pearlfish Austrolebias bellottii”

We (Irma Varela Lasheras and myself) did detailed demographic work on A. bellottii embryos and found that these respond relatively little to being incubated in either water or air with high humidity. The eggs were incubated in multiwell plates, and this allows a very easy follow-up of the embryos, and a good yield of developed embryos. I am happy with the results and they take me all the way back to the start of my PhD thesis, when I read Prof. Michio Hori‘s thesis on Cicindela japonica, in which he did a demographic study of three stages of tiger beetle larvae with graphs similar to the one I show in this post.


Hatching 2015

The home office (2015)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!

Another winter heater?

IR ceiling heaterI 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.

Cold blackworms

There’s a lot of snow, but temperatures aren’t that low. I did overlook some blackworm (Lumbriculus variegatus) cultures that were standing outdoors. After few days of frost, there was little water left unfrozen, but the worms in there were doing fine. I’ve moved them to a warmer spot.
The culture works like this: small 1 liter container, two strips of filter sponge, aged and rain water. The worms settle on the sponges. They eat (vegetarian) fish food. Multiplication rates are not high now, as it is cold, but the blackworms doubled in number in a bit over a month. After winter, I’ll try this on a larger scale, maybe with an airstone or some Daphnids added.