Lets talk Shiro's....

Back in May, we had a very successful shiro spawning - almost 100% fertilisation rate and large hatch. Performed kuroku (selecting only the black hatchlings to keep), put them into the fry pond and in two weeks - they'd all dissapeared. that was the bad bit.

We separated 84 hatchlings and put them into a 5k litre childrens swimming pool - repurposed as a makeshift natural pond.

Those 84 hatchlings were white, but with a tiny amount of black on them. And they became an experiment, with two parts; 1 - could I raise some koi in a natural pond of that size. 2 - would the white fry with tiny about of black on them turn into shiro utsuri.

We introduced the hatchlings into the pond on 4th May, and "harvested" the pond this weekend, and the scores on the doors are:

34 koi harvested - all roughly 3 to 4 inch long.

4 of them were shiro utsuri, the others were mostly shiro muji - one or two had some red on the head.

the 4 fry that turned out as shiro's... I guess one is technically a showa as it's showing red on the head. will be interesting to see how that changes.

the "harvest" of our shiro sample..

Some interesting data points there - firstly, that we raised 34 out of 84 hatchlings in a vat of old water thats left without airation, filtration or artificial food - and worked only by fertilising the water with an onion sack of nettles (of the "stinging" variety). The growth of those fry has outstripped the kohaku's I have growing on in the polytunnel.

In terms of the colour part of the experiment - based on my observations with this sample of hatchlings - a white hatchling with a tiny amount of black is likely not to turn into a shiro utsuri.

We'll hang onto the 4 shiro's and see how they develop - there are 2 with underlying body patterns and it will be interesting to see how they develop. I dont expect any to turn into anything special - but I'll give them some more time and see if I can learn a little more from them.

Last weekend, I re-ran the same shiro spawning that produced this sample of hatchlings. Yes - that's the same female spawned for a second time in the same season. And this is the second year I've done that successfully.

She spawned successfully on the first night - and lots of eggs once again. Fertilisation rates looked low, but we decided to try rearing the eggs on the spawning ropes outside in the fry pond - protected within one of our new cage nets.

Turns out that the eggs didnt fare very well outside - there are some hatchlings, but barely any. But inside - we've had several thousand hatchlings from the eggs she laid around the spawning tank. We drained down the tank tonight, and syphoned the hatchlings into the fry pond.

Here's a video of the bonus hatchlings we found in the spawning tank:

click- video link

The spawning ropes in a cage net in the fry pond

It's a small hatch, but at this stage of the season - with 2 fry ponds sitting empty - we don't have much to loose. And with a bit of luck, we could have enough of a harvest to finally have a go at shiro selection, and to see what this parent combo produce.

On the East of England show - the fish I brought back - I'm taking them through a course of MG & F as a precautionary measure and plan to spawn my new female next weekend. Depending on how she gets on - and with one more fry pond laying empty - I may also try my other two kohaku females for a second time this season.

Oh, one more thing - I have a waste water pond , which is where all the water that the drums expell goes to. So - what is this shoal of kohaku's doing in there!

It's a mystery how they got there - my best guess is from my keepers growing on tank. But I'm not absolutely sure. What I do know is they're attracting a local heron which isnt good news... especially as it's clawed the plastic cover of my polytunnel in 3 places; above each of the 3 tanks!