My CPD fry are dying after 2 weeks. Help!

[Simon]

Hello everyone. I have been reading the forum for weeks now but only just signed up.

I have a big problem!

After carefully applying a hybridised version of the many breeding techniques I have learned here, I had success on my first breeding attempt with my CPD’s here in Sydney. Approx 30 fry hatched over several days between the 1st and the 5th of September after I had removed the parents from the breeding tank. All was going very well and they were initially fed on green water as well as a technique I use where I stir up the sediment of the tank that I believe releases a multitude of micro organisms into the water column. From there I started adding vinegar eels and using Sera Micron made into a solution and added by pipette. There bellies were pink and full and they were growing well. I was changing around 20% of the water every third day. Tank is 5.5 gallons, temperature 22 C, pH 7.2, negligible levels of ammonia and nitrates. Tank is well planted with a coarse gravel substrate and a foam filter. The only other inhabitants are 3 red cherry shrimp.

So – these fry are now a little over two weeks old and in the meantime I added an egg laying container from another adult CPD tank tank out of which hatched a further 15 or 20 fry. These younger fry have now been free swimming for between 4 and 8 days.

Now to the problem….. in the past 48 hours the number of the older fry has been diminishing fast. From the original 30 or so, I estimate there are now no more than 8 or 10, yet the number of the newer fry seems to remain constant. Something is clearly causing the older fry to die off and I don’t know what it is! I have searched for the dead ones but have seen only one or two at best, however I imagine that once they die and sink into coarse gravel they rapidly decay or become shrimp food.

I have invested a great deal of time and quite a lot of money into setting up my CPD breeding system and as such I am feeling very disappointed by what’s happening. I will be very grateful for help, suggestions or solutions.

Cheers,
Simon.

[BallAquatics]

Hi Simon, welcome to the forum. Sorry to hear about your fry. Just off the top of my head, I would suggest larger water changes on a daily basis. Have you checked the water for ammonia or nitrite? Your other parameters sound good.

Dennis

[Simon]

G’day Dennis –
Great to get your reply!
I test ammonia and nitrates along with pH and at the time of the fry dying both were in the lowest band of their respective Sera test kit charts.
I agree that larger/more frequent water changes might be the answer, but if ammonia and nitrate are both very low, what is it that accumulates in the water of a fry tank that is so harmful to them?
I subsequently have a new batch of around 30 fry (hatched in a 20 litre plastic bucket) that I’m hoping to have better results with.
Cheers,
Simon.

[romica]

what kind of filter do you use?

I am keeping my CPD fry only in tank with air-stone filter in the firsts 2 months, otherwise the risk of being absorbed by the filter is high, especially at night

[Simon]

Hi Romica –

I use only a small air powered sponge filter with a fairly low rate of airflow.

Since my original posting I have had better success with a subsequent batch of fry. In this instance I have been doing a daily water change of around 30%. The majority of these fry have survived now for a couple of months and are probably big enough to be put in with adult CPD’s without incident.

I’m about to embark on my next breeding effort in the next day or so which I’m looking forward to.

As we are entering summer here in Sydney I am also about to stock an outdoor 140 litre pond with CPD’s. It will be planted with a variety of pond plants both rooted and floating. I imagine that it won’t be long until I see some fry appearing in there as well (I hope!)

Cheers,
Simon

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