Please Help! Fry Dying After Day One.

Please Help! Fry Dying After Day One.

Postby Fijiblue » Wed Dec 12, 2012 10:09 am

I have been raising fry from both of my pairs (O's and Onyx) for the last two years off and on - never had any problems and had great success rates. I recently started pulling batches again about three months ago and now I can't get majority of the fry to make it past day one! I have tried just about everything from changing the parents diet to getting new cultures of rotifers - nothing helps. I typically wash out the hatch tanks, heaters and air stones with hydrogen peroxide and water. I then drain the tank water from the parent tank and add fresh water to drop the SG down to 1.023 to better accommodate the rots at 1.018. Once the tank is up to 82-83 degrees, I bring over the flower pot with the babies and aerate them with straight tubing (no air stone). I tint the water until I cant see the bottom with nano and then add the rots (pretty dense). Once the fry hatch, I take out the strait tubing and add the air stone on a low to moderate rate. The tank is than lit with an indirect small PC bulb and on for 12 hours a day. By the next day, majority of the fry are dead! My last batch I had 5 survive past meta. Any help would be greatly appreciated.

Parents Diet: Spectrum with occasional Mysis & Prime flake
Hatching Tank: 2 1/2 gallon wrapped in black garbage bag
Fry Water: Typically parent tank water (SG 1.025), but I have used fresh aerated saltwater
Temp: 82 degrees
Aeration: Airstone with low to moderate rate
Roti Diet: Reed RG
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Re: Please Help! Fry Dying After Day One.

Postby onsan » Sun Dec 16, 2012 8:39 am

what are their behavioural habits?
do they swim into the sides? the bottom? mingle around?
can they be seen hunting?
do you have any sort of biological filtration? do you test the water quality post-mortality? how's the ammonia/nitrite/pH?
how long do you take to drop the salinity? have you compared this with not dropping salinities? -> I'd be more concerned about getting fry to survive than their food, no good keeping their food alive if there's nothing to eat it. I ran my rots at a higher salinity, I took a hit on reproduction rates but I didn't have the concerns with osmotic shock.
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Re: Please Help! Fry Dying After Day One.

Postby rrcg50 » Wed Dec 19, 2012 6:17 pm

Rotifer density is too high. Also keep the lights on 24/7 for 3 days. That should solve your problem. Also if that doesn't then it might be your phyto
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Re: Please Help! Fry Dying After Day One.

Postby Jclaas » Thu Mar 06, 2014 3:34 pm

What could be wrong with the phyto?
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Re: Please Help! Fry Dying After Day One.

Postby Amie » Sun Mar 09, 2014 3:17 pm

Since this is an old thread, we probably can't get answers from the original breeder as to where their phyto was coming from. But questions should have been asked about the origin of the phyto. For example, was it live, or was it paste? Was the breeder raising the phyto themselves? Had they recently put fertilizer in the phyto? What was the density of the phyto cells? If they were raising the phyto themselves, and the density had reached capacity, then there would be a lot of 'die-off' and the ammonia levels in the water would have killed the fish quickly. Since it was indicated that phyto was added to the water until the bottom of the tank could not be seen, there is a high probability that high ammonia levels killed the fish. Before the eggs were added to the tank, nitrates and ammonia levels should have been tested.

Keeping the lights on 24/7 for 3 days is a must, as stated by rrcg50. Not only does it allow the fry to eat throughout the night, but it prevents the ph from dropping when the lights go out.
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Re: Please Help! Fry Dying After Day One.

Postby Jclaas » Fri Mar 21, 2014 2:51 am

how is it that light effects the PH? I am under the impression that co2 effects PH
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Re: Please Help! Fry Dying After Day One.

Postby onsan » Tue Apr 01, 2014 6:19 am

live algae.
algae photorespiration consumes CO2 (w/ light), elevating pH; algae respiration produces CO2 (w/o light), depressing pH.
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Re: Please Help! Fry Dying After Day One.

Postby Jclaas » Tue Apr 01, 2014 6:48 am

onsan wrote:live algae.
algae photorespiration consumes CO2 (w/ light), elevating pH; algae respiration produces CO2 (w/o light), depressing pH.


That makes sense, duh. Thanks, you are clever :).

My phyto has a pH of 9-10 with lights on 24/7. Should i change to a 16h photo period? I want to maintain it at 7.9 or less to prevent metals from leaving the phyto water and so that the high pH does not kill the rotifer culture.
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Re: Please Help! Fry Dying After Day One.

Postby onsan » Wed Apr 02, 2014 9:48 am

phyto should have a dark period, different cell processes take place during periods of darkness that promote reproduction.
phyto focus on producing chemicals/energy during periods of light which are later used for cell division during night periods.
kinda like how we need sleep so that our bodies can regenerate, repair and grow.

whilst studying, we experimented with photoperiods and frequencies, for the particular species (chlamydomonas i think it was) we found periods of 6-8hrs light followed by 2-3hrs of dark where the most productive.
by breaking it up like this we also saw a flatter pH profile due to CO2 depletion/production, compared to 12:12hr, and a lower overall pH against 24hr periods as you would expect.

strong aeration can go a long way in reducing the effects of CO2 levels on any given system, it promotes gas exchange which through partial pressure releases/absorbs O2/CO2, stabilising pH further, however if you're co-culturing this may be a problem for rotifers or the like.

really stretching my memory here, but I think that most species of algae also find the bicarbonate/carbonic form easier to utilise than carbonate, pH 7-8 is generally more favourable.
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