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Kohaku fry moved into the fry pond

I’ve reached another milestone in my project, and the hatchlings from kohaku spawning #1 are now in their fry pond.  It’s always a nervy moment, tipping a bucket of hatclings into a fry pond and relying on nature to feed them for the next 2 weeks.  It’s nail biting time for the next few days, when I'll find out how they settle in.

Catching the hatchlings in the cage net was simply a case of gathing the cage net up and pooling the hatchlings in small sections where we could scoop them up with a bucket.
Hatchlings are free swimming, and looking for food, so time to get them into their fry pond


I gathered them up in the cage net, and moved then by bucket into the fry pond.  There were around 8 bucket's worth like this from the cage net, and another 2 buckets like this from the area outside the cage net.

And, here's a short vid of those fry in the bucket:  Video link


Draining down the spawning vat, using a planting basket covered in net curtain material to stop the fry being pumped out.  Once the water level is low enough, I gathered the fry up and moved most out by bucket.  The last few were awkward to catch so I syphoned them using a garden hose - just like last year.

The decision to put them outside, rather than rear inside  ->  The fry pond went clear a few days before the hatclings were ready - which suggests the pond has a good food source for the fry.  This opened up the possibility of putting the fry outside rather than trying to rear them indoors.  The only concern I have is that I observed a large daphnia bloom, which I would have preferred to happen in 2 weeks time.  So, I’m not sure whether that’s going to work well for the fry at such an early stage in the development – time will tell.  There’s also the temperature to consider, and the water temp outside was a little cooler than I would have liked at 16 C at the time the hatchlings went out.  I moved some green water from my other outdoor pond into the clear water pond, and also a small amount of fertiliser to give the pond life a boost; logic being that the daphnia might have used up too much of the underlying food source and so feeding the pond with green water and some fertiliser would help boost the rotifer and daphnia populations.  An overly green pond is also a problem, and you might remember that last year I lost almost all my shiro hatchlings from gas bubble disease, which coincided with green water.  So, adding fertiliser is a balancing act and I am still learning how to manage the fry pond to maximise it's potential.

On kohaku spawning #2.  It's a wipe out, which is the second time in a row for her.  Lots of eggs, but none fertilised – the same happened last year with a different pair of males.  So, she’ll be on the move.  On the upside, I’ve completed the bottom drain adjustments that will enable indoor rearing of hatchlings in the 10k vats in the polytunnel.  Just need to clean the pond and the gear and then get on with another spawning.

I’ve filled one of the 10k tanks with fresh water so I have enough to hand for water changes on my next spawning – which I’m planning to kick off this weekend.  I’m waiting to see whether the second outdoor pond reaches maturity over the next few days before deciding on the next set to run with.
The next few evenings will give me a chance to clean the spawning ropes and both spawning vats (again), ready to use this weekend.  And I will also spend time observing the hatchlings and also the oyagoi to keep an eye on things.

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