Exactly 1 week after they were born, and around 4 days after they hatched, today we released the fry from the spawning that took place on 22nd/23rd April to the mud ponds.
Late yesterday afternoon Bill completed the final stage of the fry pond preparation that has been detailed over the last couple of posts, that being to pour canola oil onto the the pond surface. I mentioned the other day how quickly the ponds get populated with all manner of aquatic life. Sadly not all of that aquatic life is entirely fry friendly, indeed some of the insects and their larvae are positively fry predators.
Many of these kind of insects will breath air at the surface of the water. The layer of oil prevents them doing this and as such they drown. Evidence of the effectiveness was already apparent.
Transferring the fry to the pond obviously takes care and patience, it doesn’t take much to destroy the fry at this stage. The enclosed net is slowly reduced in size, the sides being rinsed with water as the wooden pole moves along to ensure no fry are stuck to the net.
The fry are then carefully scooped from the net and placed in the bag by inverting the net and touching it on the surface of the water inside.
The Kohaku fry are all one colour at this stage, the Showa fry vary, some being black, others yellow or white. Generally at this stage ‘kuroku’ selection is undertaken, to remove all but the black ones, these are the kuroko, literally black babies. Purdin Koi Farm made a decision a few years ago to scrap doing kuroko selection as it was not time or cost effective to do so. I have to say kuroko selection is quite possibly the single most boring thing you can do for a whole day. In Japan whole families or hired staff will gather to assist undertaking it. I for one am grateful not to be sitting around doing it for days on end! In a month or so time when first selection gets done the ‘non-showa’ will soon be rejected.
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At the mud pond the fry are carefully released into the water. The good news today is that all transferred very well and soon set off exploring their new surroundings.
The fry were given some food on release, and will now be fed daily in the morning, as well as enjoying the natural food that will start to proliferate in the pond.
Next Sunday the process will all begin, with another round of spawning.