Some weeks ago, friends from the Portuguese Killifish Association explained me how to culture blackworms. They’re in a shallow tray since then at room temperature, the water gets replaced few times per week with aged water. I rock the tray every few days, this is said to cut some worms in pieces making them regenerate and multiply. The tray has some rocky material to help that and to provide hiding space. It is biological aquarium filter material. Food: aquarium wafers containing Spirulina and courgette cubes. Amazingly, they did double in quantity over these two-three weeks!
Ponds with an abundant supply of fish food are precious. Few hundred meters from home I found a ditch with plenty of Daphnia. Moreover, Chaoborus, leeches, and other annoying by-catch which try to eat our fish seem so far absent. So I cycle there in the morning, swish my net just once or twice, happiness…
Fresh tubifex is an important staple food for my killifish. Keeping it alive and in good shape for a while can be a heck, especially during summer. Accidentally, I found out that clumps can be stored well in the fridge or in cool conditions in an open one liter container – or a larger volume – with clean water, and that this works way better and that the water stays clean much longer when I add some sphagnum moss (Sphagnum magellanicum)! Clumps with some extra water can be moved around in breathing bags easily. This makes life a lot easier.
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.
Last Friday, I was cleaning some tanks that had been standing outdoors for months and where I sometimes dump leftover food. To my surprise, several of them have nice populations of roundworms, like the blackworms in the photo. Balls of worms half the size of a fist sometimes.
These tanks were all standing in a cool spot in the shade. This looks like a new opportunity….just use some empty tanks to raise food during winter for the next spring and summer!
My Artemia is hatched without aeration, at room temperature or a bit warmer than that. Often the nauplii are not hatching yet after 24 hours, when I would expect so. I took such “hatches” with me to my garden in a small bottle. The bottle gets shaken during transport, which takes a bit more than half an hour, et voilà, when I arrive and pour the bottle’s content in a small tupper, after about an hour I have a great hatch! So now I use this to synchronize hatching to the time when I want to feed my alevins.
Sometimes chironomid larvae appear in tanks that I leave standing somewhere. It is always great to discover them, as they are fantastic live food. This morning I found many in a shallow polystyrene foam box standing on a table in a spot which receives direct sunlight from about four in the afternoon on. The polystyrene foam makes it very easy to spot and collect the larvae in the morning, when they are still near the surface. The box has been standing in this spot since about a month, containing rain water of about 10 cm deep. I throw surplus Daphnia in it, and it contains a small amount of very small organic particles on the bottom.
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.
When I return home with a batch of pond food, I bag everything in small breathing bags. This works great, I haven’t observed any mortality so far. Every now and then, I also store red bloodworm and tubifex worms in the fridge in breathing bags.
Afterwards, I wash the bags carefully with tap water and reuse them. More than ten times so far.
As spring proceeds, it is not always easy to collect pond food with the right size and in the right abundance for all fry. For example, when fishing for food I now need to skim the water surface carefully to get the smallest zooplankton. Contrary to my original plans, I thus decided to raise some Artemia. It is used as a supplement, or as the basic food to raise alevins to a size where I do have zooplankton available in.
To reduce noise and save some energy, I don’t use an aerated and heated bottle anymore. Siberian Artemia ggs harvested from Kulundinskoe Lake are hatched in small containers, in volumes of 500 ml to which I add 10 grams of seasalt. The Artemia hatches gradually at room temperature. When abundant, I separate the husks from the nauplii in a bottle with a valve. The nauplii are tapped and rinsed with tap water (which doesn’t contain chlorine).
This type of Artemia nauplii survives well in the fish tanks, often until the next morning.