A. Oscillaris Dead Loss on day 1 after hatch

[FlyboySMB]

This is the 3rd hatch I am trying to raise. The first hatch 5-14-11, I have one Juvenal still alive, the next hatch 5-27-11, I have ~ 10 Juvenal/larvae still alive & last night 6-7-11 I had another hatch.

I started with over 100 eggs last night (~1.5-2" circle) on a tile that I moved to a larvae tank filled with parent tank water (2.5 gal tank) with an air stone close to and a bit over the eggs. At 7AM this morning, it looked like about 75-100 larvae swimming around with about 50 or so dead on the bottom. I vac'd them up, added live rots & some green water. At 11AM, I had lost over half the larvae, another 20ish dead on the bottom with 15-20 still swimming (and most of the green water looks to have been eaten by the rots).

Is this typical dead loss? I am wondering if the air stone I have on the eggs for hatch night is too strong (~30-40 bubbles/sec) & I am damaging the larvae when they hatch. After the hatch, I move the air stone under the heater & turn down the air rate to ~ 5-10 bubbles/sec.

Any thoughts? I think my numbers are improving, but nothing like I see on other posts with 50-75 Juvenal from one hatch (or at least I assume they are from one hatch).

Pics

Thanks,
Steve

 

[billsreef]

With losses like that right at hatch, the first thing I question is parent nutrition. What are you feeding the breeding, and how often?

I usually keep the air pretty strong the night I expect hatch, and turn it down first thing in the morning. Another thing I do is get a rotifer bloom started in the hatching tank a couple of days before the hatch. This way there is plenty of food available as soon as they hatch.

 

[FlyboySMB]

Thanks for the reply BIll,
I was feeding only pellets once daily & some mysis once a week up until I noticed them laying eggs a couple of months ago. For the last month, I have been feeding ~ 3 times a day with a combination of frozen Formula 1 & 2, mysis soaked in selcon, "Rods original blend and Ocean Nutrition Formula 2 pellets. I have noticed the color of the eggs at spawning really improve (bright orange on spawning) since I improved the feeding. How long would it take for the improved diet to be seen in the eggs & larvae?

Thanks,
Steve

 

[duncaholic]

Another thing to consider...

I have far less dead loss when I use a larger rearing vessel. I like at least 10g to start with. seems to buffer against problems. JMO though. And like Bill said, I also prep my rearing tank with a live rot culture a few days in advance.

 

[FlyboySMB]

Is there such a thing a too many rots? I felt I had too many on my first batch and they were loosing their nutritional value, so I ended up "scooping" them out with a plankton cup & replacing with new rots. I usually add green water 2 or 3 times a day, just enough to tint the water.

I hear what you are saying about the size of the larvae tank, but I don't think it's an issue the first day or two & only an issue if you don't maintain quality water. I will slow down growth rate, but I have not had enough larvae for that to be an issue thus far.

Thanks for the comments!
Steve

 

[billsreef]

With the improved diet over the past month, I'd expect improved egg quality pretty quickly. I'd also echo duncaholic's suggestion of a larger hatching tank. My routine is to use a 10 gallon tank, half full, for hatching and initial larval rearing. There is definitely something to be said for volume, even at the hatching stage. As for rots loosing nutritional value, so long as there is a tint of phyto in the water, they will be good.

 

[FlyboySMB]

ok, I will try a 10Gal next batch.

Thanks