Akyndinos failure...again...questions!

[mattydub]

Hi all...a "good friend" recently let me try to improve our luck at raising some akyndinos, but I failed miserably....I am seeking assistance for the following.

My theory is that the rotifers multiplied too fast, killing the babies.

Here's why:

Night 1, transferred babies (hundreds) to my home (short drive) and put them in about 7g of parent water (75.7 degrees), added rots and small amount of IA... Lights off until "morning" for 16/8 cycle began. Checked in on them and all was well, hardly any die off at all! Everyone was really hunting well, bright green bellies, no hanging around airstones, or heater, and rots had cleared water. So I dumped some more IA in and let em go. Afternoon of day 2 I did small water change b/c I noticed a few dead ones on bottom. when I say small water change I'm talking about maybe 1/2 gallon. I used air line to siphon bottom "clumps" of poop, dead babies, etc. So...now I'm noticing dead babies near air stone in corner of tank. AND LOTS of ROTS. Water was clear though, so I fed IA again. When I came back just before night of day 2 all dead. ????

My thinking was that the rots were just so dense they starved the babies of oxygen?

So...
1) how am I supposed to measure the rot culture's density?
2) Should we try NOT to co-culture to keep the water as pristine as possible for the fry?
3) Will going longer (essentially starving the rots to almost cyst stage) between adding IA make a big difference?

Thanks so much for all of your help.

 

[JHardman]

A couple of things come to mind...

1) Yes you can over do it with co-culture. You need to maintain enough rots so that a larva has one in hunting range pretty much all the time. But if you over feed IA, you will drive the rot population thru the roof. A little IA several times a day is much better than one dose a day.

2) Your temp is too low. Get it up to around 80Ã"šÃ‚°F at the least. Yes higher temps mean less O2 and greater rot production, but it also means getting the larva hunting and growing quicker too.

 

[Kathy55g]

Not a good idea to starve the rots. Nutrition for the larvae comes from the stomach contents of the rotifers.

Live phyto seems to have a better track record in co-culture with the larvae. It doesn't start to rot until after it dies, and it doesn't die until the rots eat it. Dead phyto can begin to decay the minute it gets warm enough.

Live phyto continues to photosynthesize, thus contributing O2 to the water, and sopping up ammonia as well.

Dead phyto does not do these things. So not only do you have rotifers consuming O2, but also the bacteria that decompose the dead phyto.

Also, I agree the temp should be closer to 80.

Rots can be calculated using a microscope, but barring that, a slide viewer or magnifying lens can give you an idea on density.

 

[mattydub]

wow...great posts folks! Thank you for your help/thoughts....

We have a HUGE nest this time, going to hatch Monday night. I'm taking half with me to try and feed as we go...and Sanjay will be doing the other half co-cultured.

I'll try to take photos this time and keep everyone updated.

Thanks again....