[dwalstad]

In Nov 2019, I posted a revision of my brine shrimp article on the aquarium page of my website. It contains new material on hatching dishes, decapsulated eggs, and several comparisons of nauplii as a food source. (Interestingly, decapsulated eggs fed directly did very well in these studies, actually slightly better than nauplii alone and MUCH better than other dry foods.)

Recently, a thread in the El Natural forum has diverted onto hatching brine shrimp. So I started a new thread in this forum.

One question concerned the efficacy of the new hatching dishes and the need to sterilized dishes between harvests:

From Mysiak (12/09/19): I found out that I had to clean the dish with ordinary unscented bleach before starting a new culture, otherwise the yield was always smaller for consequent cultures, up to the point of practically zero hatched artemia. Rinsing the dish with hot water and paper towel wasn't enough, only bleach "restored" the full potential of hatching. I am not sure about the exact reason, but even minimum leftover of bacterial film somehow interfered with brine shrimp hatching rate.(Quibang reported almost identical results on 12/31/19.)

The difference between my results and those of Mysiak/Quibang is that I use an AWC (aquarium water conditioner) for all my hatching preparations. AWCs have many beneficial properties. I use them to prevent metal toxicity, but the AWC in this case may be counteracting a different problem. Toxic bacterial LPS (lipopolysaccharides)?

Another insight provided by Quibang on 1/3/20:

A little update on my brine shrimps experiments. I've tried to add brine shrimp food (dry algae powder) to the dish. I thought it could make them a little bigger/more nutritious for my fish. The experiment doesn't seem to be conclusive. I've noticed a drastic reduction of the number of brine shrimps to be harvested.

Nauplii are not able to eat anything for the first 8 hours, so adding food doesn't do much good in this instance. As you have reported here, it only creates problems. The hatchery dishes are just for quick, easy harvests of freshly hatched eggs. (I only add food for my longer-term cultures in large, aerated bottles.)

 

[Guibang]

Nauplii are not able to eat anything for the first 8 hours, so adding food doesn't do much good in this instance. As you have reported here, it only creates problems. The hatchery dishes are just for quick, easy harvests of freshly hatched eggs. (I only add food for my longer-term cultures in large, aerated bottles.)

Thank you for this piece of information. I won't try to feed them anymore then. At least in this dish.

 

[mysiak]

Update to my little amateur experiment, as discussed in previous topic:

1st batch - 4 teaspoons of salt, pinch of baking soda, 4 drops of water conditioner
~36 hours since start - I harvested big amount of shrimp - up to the point that water almost couldn't get through the sieve
~48 hours since start - still big amount of shrimp, but water could drain without issues (roughly 50% of the previous amount)
~72 hours since start - the last harvest of shrimp, definitely the lowest yield, but still able to feed my small colony of Neoheterandria elegans (~40 specimen)
- from my previous experience, this is my usual amount of brine shrimp when starting with disinfected dish.

2nd batch - 4 tablespoon of salt, pinch of baking soda, "a squirt" (~1ml) of water conditioner (I realized that it's not very potent, so 4 drops probably wouldn't do anything).
~36 hours since start - judging by an eye and speed of water drain speed, the yield is about 50% of the previous batch at the same time
~48 hours since start - almost no new shrimp hatched
~76 hours since start - this will be tomorrow, but I don't expect any miracles
- from my previous experience, this is my usual amount of brine shrimp when starting 2nd batch without disinfection.

For the third batch I'm going to skip bleaching again, but this time I'll use different water conditioner (much more potent Seachem Safe) to rule out possible issue with my currently used water conditioner (Sera Aquatan).

 

[dwalstad]

Very interesting!

 

[Guibang]

Thanks for your feedback Mysiak.

Have you always used 4 teaspoons of salt? I only use one and a half like Mrs Walstad suggest in her article. I have pretty good results with only 1 & 1/2. Like you describe in my first harvests water has difficulty to get through the sieve. Maybe you should try with less salt.

 

[mysiak]

Oops, not sure where I got the 4 spoons idea, probably remembered the instructions in the article wrongly. You are right, even before this experiment I used to use less salt. 3rd batch with Seachem Safe and 4 tsp of salt is already running, so too late to change it. Although high salinity doesn't seem to impact the first "clean" batch, so it's probably just a waste of salt. Nevertheless, my next attempts will be with 1.5 tsp of salt. Thanks for noticing and letting me know

 

[dwalstad]

In rethinking this:

Mysiak, how many eggs did you add? I always add 1/8 level tsp or less.

I think that little things could make a difference. I generally start harvesting brine shrimp at 24 hr and continue doing so 3-4 times per day. I don't wait until 36, 48, and 72 hr for 3 big harvests. If waste products and oxygen are problems, this faster population reduction might make a modest difference.

Four tsp of salt per 3 cups of water would definitely change everything. Whatever problem is going on would be accentuated by a very high salt concentration. It would stress the nauplii unnecessarily.

When I clean the dish after a harvest, I sponge clean all the sides of the dish and the plastic ring to remove any attached biofilms. Attached biofilms would consume oxygen and possible generate bacterial toxins? I noted that the instructions mention sterilizing the dish after harvests, but I thought this was unnecessary.

As to lighting, Mysiak may be on to something. I just added strong light because of literature, not due to any experiments. Yesterday, I started a hatch without much lighting and the harvest at 24 hr seems to be pretty good. If the shrimp keep hatching tomorrow, that would be nice. (I have some houseplants that could use that light.)

 

[Guibang]

I've never used any specific lighting and it works well. Maybe it'd work better with a special lamp. Haven't tried it yet.

 

[mysiak]

I am using the measuring cup/spoon which came with the hatching dish (as in the product picture). For this test I am adding 1 full cup/spoon. In the past I added about 2 spoons (the maximum I tried was 4 if I remember well), but the yield wasn't much bigger, so I was probably just wasting artemia eggs. Btw. I always wondered, how do you measure 1/8th tsp? I can hardly judge 1/2 of any kitchen spoon, let alone 1/8th. Coming from Europe with nothing but metric system, I simply can't fathom it.

Usually I'm harvesting hatched brine shrimp whenever I am at home and there is enough of them to bother with feeding the fish. However for this experiment I tried to simplify my eyeball measurements of yields by harvesting at "fixed" times.

Regarding the cleaning - I believe that I use the same procedure - remove the old water with shells and unhatched eggs, clean whole dish, white dividing disc and sieve with sponge and a drop of dish soap. After that clean thoroughly under running hot tap water. If I'm using bleach, I skip sponge and soap - I just pour clean bleach into the dish and fill in with water until it's completely full (about 1:1 ratio, the exact ratio doesn't seem to matter). I keep white disc and sieve submerged as well. After few minutes I clean everything under running hot water and use the dish for next batch.

On a side note, doing this experiment just reminded me how awesome Grindal worms are. One culture of worms occupies roughly the same space as this hatching dish, provides steady, daily and usually also much higher yields than brine shrimp and requires much less maintenance/preparation. Running multiple or bigger cultures allows several full harvests per day. Anyone hatching brine shrimp regularly should think about starting Grindal or white worms culture

 

[mysiak]

Update:
3rd batch - 4 teaspoons of salt, pinch of baking soda, a pinch of water conditioner (Seachem Safe)
~36 hours since start - I counted about 10 hatched shrimp
I am going to keep the dish untouched for another 24 hours, but it most probably won't get any better.

As discussed previously, I inadvertently overdosed the salt and in my last attempt also the water conditioner (it's extremely concentrated - 100mg per 100l of water, so correct dosing for 1l is next to impossible). However from my previous experience this is exactly what I was observing with correct salt concentration and without a water conditioner.

For my 4th batch I'm going to disinfect the dish with bleach and repeat the overdosing with salt and water conditioner. I'm really curious what will happen

 

[dwalstad]

I am using the measuring cup/spoon which came with the hatching dish (as in the product picture). For this test I am adding 1 full cup/spoon. In the past I added about 2 spoons (the maximum I tried was 4 if I remember well), but the yield wasn't much bigger, so I was probably just wasting artemia eggs. Btw. I always wondered, how do you measure 1/8th tsp? I can hardly judge 1/2 of any kitchen spoon, let alone 1/8th. Coming from Europe with nothing but metric system, I simply can't fathom it.

Usually I'm harvesting hatched brine shrimp whenever I am at home and there is enough of them to bother with feeding the fish. However for this experiment I tried to simplify my eyeball measurements of yields by harvesting at "fixed" times.

Regarding the cleaning - I believe that I use the same procedure - remove the old water with shells and unhatched eggs, clean whole dish, white dividing disc and sieve with sponge and a drop of dish soap. After that clean thoroughly under running hot tap water.

Your measuring spoon, the one that comes with the dish, is perfect; it holds just a little bit less than my 1/8 teaspoon. Yes, I did measure it! (I was concerned that you were using more than 1/8 tsp.)

I am very happy to report that I am getting terrific hatches with no added light. I set up the dish in the evening and kept the dish covered.

From this light-less seeding, I harvested a decent amount at 24 hours, but then today at ~36 hours, the shrimp were hatching all day long and like crazy--as usual. I must have fed my baby fish 8 times today. Each time, the little harvest cup was completely covered with brine shrimp so that you couldn't see the netting.

Make sure that your AWC (aquarium water conditioner) is designed to counteract heavy metals. Not all do and that may be part of the problem. My 'Instant Ocean' AWC is supposed to be dosed as follows: 5 ml per 10 gal of tank water.

Here are calculations for scaling down for the hatchery dish. A water drop contains 0.05 ml, so 5 ml contains 100 drops. Ten gal is 38 liters, so dosage is 100 drops per 38 liters, which is 2.6 drops per liter. The harvest dish holds about 1/3 liter (i.e, my 3 cups), so the 5 drops of AWC that I use to counteract metal toxicity is already a generous dose, about twice the recommended dose.

 

[mysiak]

The products which I tried:
-------
Sera Aquatan - "It removes harmful substances such as chlorine and chloramines, binds heavy metals (e.g. copper, zinc or lead) and protects against ammonia. At the same time, it adds important mineral substances in a bioavailable form to the aquarium water."

Standard usage 50ml per 200l, which would make 5 drops per liter.
-------
Seachem Safe - I found a lot of contradicting information about this product (and its liquid form Seachem Prime). Seachem claims that Safe does not remove heavy metals, but Prime does. However when "some scientist" analyzed the active ingredient of Safe and Prime with spectrometer, both contain only sodium dithionite (sodium hydrosulfite). I honestly don't know what to believe at this point. Marketing words of many products are sometimes too good to be true.

Standard usage 100mg per 100l, which would make 1mg per 1l. I am quite sure that I overdosed this product, though no idea by how much. I don't have such a precise scale and I couldn't find info about how 1mg of salt looks like. Sodium hydrosulfite is reducing agent and it should reduce available oxygen if overdosed, but this hasn't been confirmed in this experiment.
-------
I am going to start the next batch today (bleach, salt overdose, safe overdose) just to verify if my last failed hatching was due to water conditioner overdose or this mysterious unidentified bacterial (?) residue.

 

[dwalstad]

Okay. It's hard to sort out multiple problems, so just tackle one variable at a time. Metal toxicity may or may not be causing your problem. I don't use soap to wipe and rinse out the dish after use. Always worried that something will stick to plastic.

The Sera product sounds best to counteract any metal toxicity. Another option is to just make up your hatching solution with aquarium water; plant-derived humic acids in aquarium water will naturally bind any heavy metals. I found that even a small amount (20%) of my aquarium water counteracted the zinc in my tapwater and produced a good hatch of brine shrimp eggs.

BTW, I'm really pleased about not having to use extra light for hatching. Thanks to you and Guibang!

 

[mysiak]

You are right, I need to focus on changing only one parameter. I am too eager to test everything, but at the end it will just slow me down..

Anyway, interesting change of course and I stand corrected about my third batch:

3rd batch - 4 teaspoons of salt, pinch of baking soda, a pinch of water conditioner (Seachem Safe)
~36 hours since start - I counted about 10 hatched shrimp
~60 hours since start - quite a good harvest (in fact I harvested twice within 2 hours) - not up to the point as if starting with disinfected dish, but not a disaster as I thought initially

It seems that hatching was delayed by about 24 hours. The only thing which I changed between second and third batches was type of AWC. Just pure guessing, but maybe overdosing of AWC really depleted available oxygen and it took 1 day to re-establish the water-air equilibrium..?

 

[dwalstad]

I think that that the delay in hatching you observed could also be due to a delay in hydration of the egg, the first step in brine shrimp egg hatching.

With the higher salinity (4 tsp v. 1.5 tsp per same water volume), you've delayed egg hydration, because of osmotic forces. As the salt concentration in water increases, it is harder for water to get into the egg. In fact, at 8.5% salinity, eggs won't hatch at all; the osmotic force going into egg is equal to the osmotic force going out of egg. Water can't move into egg to hydrate egg and start the whole hatching process.

A similar thing might happen in changing the water conditioner. A different water conditioner could contain "stuff" (proteins?) that clogs up pores in egg shell delaying water entry. Thus, you could see a delay in egg hatching. It doesn't kill egg or embryo, just delays the hatching.

This is just crude speculation, BUT fun to think about.

 

[Gerald]

Speculation is always more fun and imaginative than evidence! |;>)

 

[dwalstad]

After the great harvest I reported on 1/7/2020, the next one wasn't very good. The good harvest was in dish that I hadn't used for about a week or so, so any material stuck to sides would have been dessicated--a form of sterilization.

So for the next batch started yesterday evening (1/10/20), I sterilized the dish beforehand with dilute chlorox before seeding.

I should know by tomorrow whether chlorox helped or not.

Right now I have 3 precious batches of baby guppies going. I am depending on the hatchery dish to fatten them up properly!

 

[dwalstad]

Okay, guys... I got an exc total harvest after sterilizing the dish with dilute chlorox, much better than day before

Here's the time-line for this good batch:

Seeded dish in evening (5 PM?) of 1/10/20
Got a couple good harvest cupfuls during evening of 1/11 (a 24 hr hatch)
On 1/12, I got about 6 good harvests all day long (36 to 48 hr), but I noticed that in the evening (after 48 hr), the yields had dwindled.
On 1/13, I got almost nothing, so productive hatching was over by 48 hr.​

I think in the past, I probably was getting some sub-optimal hatches depending on the vigor of my cleaning the dish afterwards. However, I dismissed the variability. Before getting input from Mysiak and Guibang, I didn't realize that the cleaning/sterilization was so important, but I realize now that it is. Thank you!

I will continue working this out to be sure. I'm also examining the light business. (It seems like the eggs, despite scientific recommendations, don't require light for hatching.) Another thing is that the lower salinity I'm using probably speeds up the hatching.

When I put this all together, I'll revise my website article, probably in a couple weeks.

 

[dwalstad]

Just posted the revised brine shrimp article incorporating new material about light and sterilizing the hatchery dish.

Thank you again Mysiak and Guibang for your comments and detailed observations. I think this article is now the BEST brine shrimp article on the planet!