what age to ween baby erectus to frozen mysis?

[CTaylor]

My erectus are 3 weeks and 3 days old now. They are growing pretty fast, and just in last few days seem to have gotten even much bigger. At what point do I start chopping up mysis and try weening?
I have about 27 raised to this point out of a birth of 175. Most of the 27 -- about 22 are looking great, the other few have much less growth. Probably not a great yield, but better than not attempting.

[rayjay]

You can start any time now. I've had batches start around the 4 week mark but other batches longer with some batches even not getting on to it until around 8 weeks.

[CTaylor]

OK, thanks. THough I made the mistake of trying to enrich the bbs with a bit of selco. A few died today .. maybe more than a few. I see that it could have caused an infection... Hopefully a few tough ones will make it :-/

[rayjay]

Enrichment of bbs is NOT a mistake. Possibly the Way you enriched them had an affect, or, there might not be any true association with those deaths and enrichment.
Like when using powdered enrichments, the selco should be micronized in some water in a blender, stored in a refrigerator for use, added sparingly to the enrichment container in order to prevent death of the nauplii before feeding.
The bbs (nauplii) can't be enriched in their Instar I stage as digestive tract is not complete, so start after about 24 hours from hatchout.
In new water with new enrichment and aeration, add the nauplii and enrich for 12 hours, adding more enrichment if the water clears. After this 12 hours they will be gut loaded.
For better enrichment, use new water and enrichment and enrich for another 12 hour period and now in addition to being gut loaded, the nutrients will have become assimilated into the flesh of the nauplii.
At this point you can use Dan's peroxide method to sterilize the nauplii before using them as food for your fry.
IME, the fry death problems don't come as much from a feeding problem as from cleanliness of the fry container and water.
I found that VERY frequent water changes coupled with extreme cleaning of the container and hitching, including wiping down all surfaces to remove the bacterial film that quickly develops, made for better success in survival rate.