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Investigating differences in brine shrimp eggs


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I had been using Coop eggs, but I ran out, looked around and some other promising brands.  I thought I'd share some of my observations and measurements.

First, they seem to hatch about the same.  I use rock salt for a salinity of about 25ppt (1.017 specific gravity @ 77F) and tsp of baking soda per liter, which gets my Ph to  about 8.5.  I use two water bottle hatcheries that hold about 900ml each.  And heat them each with a 5W that's on for 20 minutes out of every hour,  which keeps it around 80F.  I get good hatches in 24 hours.

I took some measurements of the eggs and nauplii:

Coop eggs are an average of 0.28mm in diameter after 24 hours in water.  Brand X is 0.20mm.

Coop nauplii are 0.53mm long and 0.19mm wide, on average.  Brand X is 0.5mm by 0.15mm.

That 0.05 mm reduction in width seems small, but by a very crude estimate, it suggests that the coop nauplii have 70% more volume than brand X.  Brand X nauplii subjectively look much smaller than coop nauplii.  

I know some people say that smaller brine shrimp can be eaten by smaller fry, but the size difference (in terms of how big a mouth you would need) seems not that large.

The biggest difference between the two, though, comes in how they shells (don't) separate from the nauplii.  The Coop eggs, I get very few sinking shells.  But with brand X, I get lots of sinkers and it plugs up the fancy RO-style valves on the bottom of my hatcheries.  It's very annoying. 

In test tubes, I tried increasing salinity to get the sinkers to float, but it was no use.  I went as high 44ppt (1.031 SG) salinity and they still sank. 😞



Edited by memorywrangler
added the photo.
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Love the comparison. Coop eggs are definitely the easiest when it come to shells floating. They are also the chunkiest ones I’ve found. 

The only ones I found that are significantly smaller are from Brine Shrimp Direct. Those are actually small enough I can get fry eating them 4 days to a week sooner than the ACO ones. 

It’s interesting when I start transitioning them to ACO eggs or if I have different size fry. I hatch both in the same Ziss blender. The ACO shells all float and the BSD ones glue themselves to the side and bottom. 

It’s nice to be able to start the fry sooner but my adults don’t even go after the tiny ones. 

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