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Issue: April 2007

A Scientific, Economic, and Common-Sense Approach to Brine Shrimp Hatching

Author: Gary Lange and Mike Hellweg

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The authors explore the theories and practicalities of brine shrimp hatching, using their own research to test previously published reports.

Part of the process in which our overall body of knowledge grows is through the so-called scientific method, wherein a scientist makes an observation, proposes a hypothesis regarding that observation, tests that hypothesis through various methods, reviews the results of those tests in regard to the hypothesis, and either modifies the hypothesis and repeats the above or publishes the results of those tests to other scientists for them to comment upon and attempt to replicate to prove or disprove the hypothesis. This is a much simplified version of what is known as peer review. It also works for the aquarium hobby, and TFH provides an excellent international forum for hobbyists to perform our own version of the scientific method.

In the November 2006 issue of TFH an article on hatching brine shrimp appeared, and the author reached some conclusions that we (Gary and Mike) questioned (remember, this is the intent of publication). We don’t mean this article as a criticism of that author’s work, but rather a review of our attempt to prove or disprove the methodology she used to reach her conclusions. The results we obtained appear to invalidate some of those conclusions, and some others need a bit more explanation.

As a scientist, Gary became concerned by the science behind some of the conclusions reached by the author. Mike, the business guy, decided that the economics might need a bit of investigation. While our perspective is that of advanced hobbyists with several hundred species spawned between us and tens of thousands of fish raised successfully, the techniques outlined for hatching and feeding fry brine shrimp nauplii didn’t seem quite practical for the average hobbyist either. In this article we will explain our methodology for testing and proving or refuting the science, the economic reasoning, and the hatching methods given in that article.

We hope this article will leave you with good common-sense methods for hatching your own Artemia nauplii. You will have the confidence that you are using proven techniques that will allow you to hatch and feed the optimum amount of the most nutritious shrimp, and cost you the least amount of both money and time.

A Little about Brine Shrimp

Brine shrimp has been a readily available food source for hobbyists since the 1930s. Unlike other live foods, brine shrimp does not need to be cultured continuously, but rather hatched as needed to provide a quick source of live food for fish. As time went by and harvest and processing methods for their eggs improved, brine shrimp became a staple not only for hobbyists, but also for the aquaculture industry around the world.

Brine shrimp are known to science by their genus name, Artemia. It is not entirely clear what species we are dealing with in the hobby, but most species have similar requirements, so it’s not that important to us as hobbyists. There are likely several species found in very salty conditions all around the world, from Australia to China to the Middle East to the United States. They are a major food source for migratory birds in many places. Much research has been done on their nutritional profile, life cycle, proper feeds for their culture, and every other aspect of their lives.

We won’t go into details here, if you want to research it further we suggest the Plankton Culture Manual by Frank H. Hoff and Terry W. Snell, which is packed with culture and nutritional profile information on Artemia and many other planktonic animals. For our purposes, we’ll mainly look at the first 12 or so hours post-hatch, where the nauplii are most nutritious with a body-fat (several different HUFAs that are essential to fish growth) content of up to 32 percent of total body weight, according to Hoff and Snell. As they reach the end of their first development stage, called the first “instar,” this can drop considerably—by as much as 39 percent (Hoff and Snell).

Over this time period, which can last about 12 hours, they do not feed, as their mouth and anus are not fully developed. So they live off of their fat reserves, gradually depleting their value as a food source for our fish. If not fed by the end of the second instar (at approximately 24 hours post hatch), Hoff and Snell report they may lose up to 1/5 of their body weight and more than a quarter of their nutritional value. We can assume by this that the sooner post-hatch that we feed them to our fish, the better the nutritional value for our fry.

Brine shrimp beyond the first molt (instar two and beyond) eat free-floating algae, detritus, and bacteria. From a hobbyist’s perspective there is little practical or nutritive value to raising large quantities of adult brine shrimp to feed your fish. Even just doing so for one aquarium would entail using much more room than would be practical for the number of shrimp raised. It is much more practical to purchase live adult brine shrimp, gut-load them, and feed them to your fish. However, newly hatched Artemia, known scientifically as nauplii, are extremely nutritious, very easy to hatch on short notice as needed, and very practical and economical.

As to the amount consumed by young fish, for optimum health and growth it is recommended by most breeders to feed the fry as much as they will eat. Obviously consumption depends upon size, so a single fry can consume dozens to several hundred or more nauplii per day. For example, some authors (e.g., Alisa Abbot in the T.F.H. book The Complete Guide to Dwarf Seahorses in the Aquarium, among others) report that juvenile seahorses can eat as many as 3000 nauplii per juvenile per day! So you can see that to properly feed a batch of growing fry you will easily utilize the entire hatch each day.

Holding part of a hatch over for another day’s feed does not make nutritional sense unless you are feeding it properly (nor does it make practical sense). Nutritionally and practically speaking, it’s just more simple and healthy to hatch out fresh nauplii each day.

Optimized Hatching of Brine Shrimp Eggs

After checking our notes we found that we both use a very similar method for hatching brine shrimp. This method has been used by both of us since the early 1980s, so it is time-tested and all of the “bugs” have been worked out.

For a 2-liter soda bottle hatcher, we add 1.4 liters of warm (80° to 82°F) chloramine-containing (that’s right, we don’t use dechlor or anything else!) tap water (125 ppm GH and 3 degrees 54 ppm KH). Add 2 tablespoons of salt and a teaspoon of Epsom salt, stirring until dissolved. This gives a specific gravity of about 1.019. Both of us add about ½ tablespoon (1½ teaspoons, by weight 4.2 g) of brine shrimp eggs to the hatcher. Many of the brine shrimp companies have suggested using ½ teaspoon/liter, but we found that you don’t have that much of a loss in hatch rate. In our hatching table we’ve used a slightly lower amount of eggs for our 1 liter and 500 ml hatchers, which is slightly closer to the ½ teaspoon of eggs per liter.

Now both of us do something that most people don’t do. We add three drops of plain, unscented chlorine bleach. In the wild, mats or rafts of floating brine shrimp eggs can become rather nasty before harvest—they serve as a home to many types of bacteria and larger critters that can be harmful in our aquaria. Our friend and mentor Rosario LaCorte mentioned that he started adding the bleach to help lower some of the potential biological load that comes along with the brine shrimp eggs, and to kill any nasty hitchhikers that might be on the outer casing of the cysts. Even with the best processing methods, some undesirable critters can get through. The drops of bleach kill anything on the outside of the eggs without wasting the time of completely decapsulating the eggs.

Without the chlorine, when hatching larger quantities of eggs, you might notice that the eggs get scummy and may even start to clump together because of the bacteria. The chlorine evaporates fairly quickly with all of the bubbling of the eggs, so it’s not around to harm the brine shrimp when they hatch.

We both hatch our eggs at a temperature of 80° to 84°F with an ambient light source nearby. Eggs are vigorously bubbled with a rigid piece of 3/16-inch tubing at the bottom of the v-shaped bottle. Many websites recommend a light source to help hatch eggs, although we haven’t checked whether it really makes any difference. At these temperatures we (and most researchers) find that almost all of the eggs that are going to hatch have already hatched in 18 to 24 hours.

Again we stress that you want to feed the brine shrimp to your fish as soon as they hatch, as this is when they are the most nutritious. Over the next 12 hours they will begin to utilize these lipids and grow. For this entire period they cannot feed, as their mouth has not yet developed, so feeding them would be pointless. At this time the biggest risk thing we have to worry about is suffocation if there is too heavy a bioload in the water, such as from a large bacterial population, or if the water isn’t circulating rapidly enough. If you wait longer than 12 hours post hatch they will have molted and they will need to be fed before feeding them to your fish. If you don’t need to hatch as many brine shrimp as we do each day then use a smaller hatching bottle (see table) and fewer eggs. You can enrich older shrimp by feeding a HUFA-containing supplement, though this will take up to an additional 12 hours after they have completed their first molt. Recently in his reading Mike discovered a method for enriching newly hatched brine shrimp or older shrimp with HUFAs.

Common Mistakes Made in Hatching Brine Shrimp

Measurements

Many people add too little or way too much salt. Either one can cause you not to have an optimal hatch. This is also true for measuring the shrimp eggs. If you start adding too much over our recommended ½ tablespoon per 1.4 liters of water, you will have diminishing returns.

Poor Quality Eggs and Improper Storage

Buy a one-pound sealed can of eggs and buy at least an 80 percent hatch rate. When you open them for the first time, pour the eggs in a jar that can be tightly sealed, store them in the freezer or the refrigerator, and add a food-grade desiccant pack to keep moisture down.

Retrieve the necessary eggs for hatching from the jar quickly and seal the lid tightly as soon as you are finished. You don’t want to keep introducing moisture to the eggs each time you open the container, and the natural humidity in the air will do that. Whatever you do, don’t bring the jar back up to room temperature each and every time you want to measure out some eggs. That’s a horrible waste of your time and it continues to freeze and thaw your eggs. Eggs stored properly will still produce high percentage hatches, even years after opening the can.

Soft Water

People living in areas of soft water have often complained that they can’t hatch brine shrimp. Measure the pH of your shrimp solution before and after hatching. If it’s still not pH 8 or higher after they hatch then you need to add some buffer to your water. Add about ¼ teaspoon of baking soda (sodium bicarbonate) per liter of hatching solution.

Too Cold or Too Warm

Below 78°F it will take up to 36 hours for most of your shrimp to hatch. You’ll end up waiting too long and end up with less nutritious shrimp as they molt into their second and third instars. Over about 86°F and the nauplii will suffocate quickly. You’ll end up with a smelly mess in the hatcher as well. If you don’t have warm fishrooms like ours, then put your hatchers in an old 10-gallon aquarium with a lid and a small 25-watt light. Check the temperature but you should be able to get somewhere in the range of 80° to 84°F degrees and you gain a light source, which is supposed to help with hatching. You can also fill a 10-gallon aquarium with 3 to 4 inches of water and a submersible heater to keep the hatcher warm. Again use a lid on the tank to keep the heat inside the tank and hatchers warm.

Not Enough Air Bubbling Through the Eggs

If the eggs come to rest they won’t hatch, and brine shrimp need oxygen to live. Gary the science nerd used a common 9- x 22-inch fish bag and measured how long it took to fill it to the 16-inch mark with air from the hatcher’s airline. He then filled the bag up to that mark with water and measured it. The flow rate is 1.6 liters of air per minute, but if you just bubble the heck out of it you’ll be close. Make sure you clean that rigid tubing out each time you clean the hatcher, too.

Reusing the Hatch Water

Tap water, salt, baking soda (if needed), and Epsom salt are all very inexpensive. It makes no economic, time-saving, or practical sense to reuse hatch water. The less than two cents per hatch you save will more than be made up for by the decreased hatch due to the fact that the reused water is filthy with biological material that competes with the newly hatched shrimp for oxygen. Sniff it. Would you use that water to raise food to feed any other animal? Why use it to raise food to feed your fish? You may have spent hundreds of hours working to get the spawn you are trying to feed, or they may be expensive fish. Why waste that time and money and use waste water?

In addition, if you use the “LaCorte bleach method” (which we strongly recommend) you will kill all of the bacteria, which will begin decomposing, and this will also compete with the nauplii for oxygen.

Finally, look at the time taken to prep the reused water. It is much more than that of setting up new water. We timed it. It only takes about 30 seconds to a minute to set up a fresh hatcher from beginning to end. Trying to filter out and remove unhatched cysts and dead shrimp from the waste water can take 5 to 10 minutes. There certainly is no time savings there.

The Hard Economics of Hatching and Feeding Baby Brine Shrimp

Iodized Table Salt: .19 per pound

GSL Eggs: Grade A, 80-percent hatch rate, $25 per pound (454 g) including shipping

½ TLB of eggs = 4.2 g or 108½ TLB servings per 454 g container

Epsom Salt: .67 per pound or 1.013 cents per teaspoon
 
 
Table:

     2 Liter Hatcher   1 Liter Hatcher   500 ml Hatcher

Water Added      1.4 liters 700 ml      350 ml

Salt2 tbsp (1.73 ¢)   1 tbsp (.864 ¢)   .5 tbsp (.432 ¢)

Eggs½ tbsp (23.15 ¢) ½ tsp (7.72 ¢)    ¼ tsp (3.86 ¢)

Epsom Salt1 tsp (1.013 ¢)   ½ tsp (.507 ¢)    ¼ tsp (.25 ¢)

Total $/Hatch    $ 0.2589    $ 0.0907    $ 0.0454
Total/365 days   $94.50 *    $33.10      $16.57
Time per day     < 1 minute prep  < 1 minute prep   < 1 minute prep
Time/365 days    < 6 hours   < 6 hours   < 6 hours
Time to reuse    > 30 hours/year   > 30 hours/year   > 30 hours/year
 

*At first glance this may sound like a lot of money, but consider that in the same time period Mike is also using approximately $200 (wholesale cost) in high quality flake food, approximately $150 (wholesale cost) in freeze dried krill, plankton and bloodworms, and a lot of home-cultured live foods. Looked at in this perspective of his spending approximately $1 a day on processed foods, at just under 26 cents a day, newly hatched brine shrimp is very economical.Now sit back, enjoy your hobby, and spend the time you would have spent worrying and reusing that nasty brine shrimp hatch water enjoying your fish. After all, isn’t that why you got into this wonderful hobby in the first place?

 

The Science of Brine Shrimp Hatching

I don’t have a microscope or a unit to count brine shrimp at home, and neither do the majority of hobbyists. I have compared 10 ml samples of two different methods and allowed them to settle in a graduated cylinder and did a quick “eye count” on how many ml of orange I had at the bottom of the container. With some of the losses suggested in the original article, however, a 50-percent loss would be easy to see (in the hatcher and in the 10 milliliter graduated cylinders). To check the different methods I put two 2-liter hatchers side by side so that the light and temperatures would be the same. I then compared the apparent hatch differences by “eyeball” and graduated cylinder to see if I could tell any obvious differences.

Test 1: Does adding a dechlorinator that removes heavy metals make a difference in my hatch rate?

Our optimized method, with 3 drops of chlorine, versus a hatcher treated with a proprietary water conditioner. The dechlorinated hatcher had more clumps of eggs, not unlike a hatcher set up without the addition of a few drops of bleach. I found pretty much the same amount of hatched shrimp in each.

Conclusion: I don’t have enough copper or other toxic heavy metals in my water or my pipes to inhibit the hatching of brine shrimp eggs.

Test 2: Is 24 hours at 82°F enough time to hatch most of the shrimp?

At T=24 hr the aeration was removed from the hatcher and the nauplii were allowed to settle for about 5 minutes. A 25-watt light source was place near the base of the hatcher to attract and further separate the brine shrimp from the unhatched eggs. We removed them by siphoning them through a brine shrimp net using a 3/16-inch rigid piece of tubing connected to airline tubing. This is our typical method of removing nauplii from the unhatched eggs for feeding to our fish. The rest of the hatching solution was poured back and incubated as before. The solution was checked at 32 hours and 48 hours to see if there were any increases in nauplii in the hatcher. The result was that no more brine shrimp hatched out.

Conclusion: At 82° to 84° degrees, 24 hours is plenty of time to hatch all of the eggs.

Test 3: My water versus RO water, optimized method.

Although both samples started out at pH 8, after hatching the RO sample was in the low 7.1 range. It was also obvious that there were fewer shrimp than in the hatcher with my tap water. The addition of ¼ teaspoon of baking soda per liter solved the problem and the two were then equal.

Conclusion: If you have soft water, add ¼ teaspoon of baking soda per liter to the hatching solution.

Test 4: Copper Toxicity and Brine Shrimp Hatching

The previous article reprinted a chart that showed that at 0.0064 parts per million copper (6.4 micrograms per liter or 0.1 micromolar of copper) only 50 percent of the brine shrimp eggs hatched. That concentration of only 6.4 micrograms of the copper metal per liter could potentially be reached using water that had been in the typical household copper pipes. The water from my pipes didn’t seem to have enough copper in them to inhibit the hatching as shown in Test 1, so I decided to add a much higher dose of copper sulfate and see if that could inhibit the hatch rate. Remember it had been stated that an equivalent of 0.1 micro molar copper would inhibit 50 percent of the hatch. I made up a 1 millimolar solution of copper sulfate and then added enough to the hatcher to make a 1.0 micromolar solution of copper (64 micrograms of Cu per liter) or 10 times the amount that was supposed to be harmful to hatching. Even a 10 micro molar solution—or 100 timesthat “harmful amount” of copper—was tested, with the result being a decent hatch rate.

Results: As shown in the photograph comparing the two solutions on this page, there really is no difference between the hatchers.

Conclusion: The effect of copper in your water on your hatch rate is an illusion. See our common mistakes section for a more likely scenario to hatching woes.

Interpreting Data

If you will look back carefully at the original article, pay close attention to the graph showing copper toxicity. They supposedly used only viable eggs by hydrating first and removing the eggs that shouldn’t hatch. We should have expected that the maximum percentage for the control would have been 100 percent or pretty close to it. Also note that they were still measuring hatching out at 70 hours or almost three days! Even the neophyte hobbyist hatching brine shrimp knows that if it takes you three days to hatch your brine shrimp you are doing something wrong.

In my field of science we build upon experiments of other experts who have performed careful experiments before us (the scientific method described above). For instance we know that if we want to grow human cells in the lab, most of them have to be grown at very close to body temperature or 37°C (98.6°F). We also know that most of the cell lines require a certain amount of carbon dioxide in the system so we have 5 percent CO2 with them in the incubator. If one were to place them instead at say, 25 degrees, and then remove the CO2, we would expect that their growth rate and survival rates would be very poor. If we were to add a few milliliters coffee to this mix at the same time though, would you be inclined to say that the coffee killed the cells? Of course not.

My point is that you have to be very careful how you interpret data and run experiments. In the world of science, the term “Occam’s razor” refers to the idea that the less complicated explanation is probably the right one, and one should make as few assumptions as possible. Applied to this case, Occam’s razor would suggest that, when you have trouble with brine shrimp hatching, you shouldn’t go blaming the copper or zinc in your water, but rather you should check first to see if your pH is too low because you live in a soft water region. Measure your salt, and make sure you are using the optimal hatching conditions.

Overall Conclusion

Newly hatched brine shrimp are an excellent source of nutrition for aquarium fish, especially fry. They are inexpensive, convenient, easy to hatch, and are readily available when needed. There is no reason to make hatching or harvesting complicated, to look for false economies in methods such as reusing hatch water, or to worry about potential “threats” to your brine shrimp posed by things such as zinc or copper (or even chlorine, for that matter!) in your tap water.

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