hatching baby brine shrimp

Hey,
Are the brine attaching themselves to the side of the tank with the natural sunlight? From everything that I have read they are attrackted to light. This is probably what is occuring.
sandy

Dear Harry:

Congratulations on the development of your male’s pouch. If he isn’t pregnant now, the physiological changes his pouch of undergone could certainly indicate that the hormones are flowing and he’s getting into breeding condition. If that’s the case, he is now serious about mating and breeding and will likely become pregnant (if he isn’t already) as soon as he can entice a receptive female to cooperate.

In my experience, mature Hippocampus erectus typically produce broods of 100-800 fry. However, a virgin male’s first few broods are smaller than normal, so that largely agrees with the figures that were reported on the German web site. This is the right time for you to get your battery of brine shrimp hatcheries up and running and hone your technique for hatching out the Artemia cysts (brine shrimp eggs).

It sounds like you’re doing exactly that and making excellent progress! I also used to grow out live brine shrimp outdoors in a big glass aquarium set atop the roof of one of the out buildings where it would receive plenty of direct sunlight to encourage algae growth. The brine shrimp nauplii are indeed phototactic and attracted to light, but the main reason they like to congregate on the aquarium glass is because that’s where the microalgae begins to grow and they like to feed on it. So don’t scrape the algae off the glass of your rearing tank, since that’s a desirable development and the newly hatched brine shrimp appreciate feasting on the microalgae growth. Here is some additional information on growing out brine shrimp you might also find helpful, Harry:

Growing Out Brine Shrimp (Culturing Artemia salina)

Under ideal conditions, Artemia reach adulthood in 8 days after molting 15 times. The easiest way to raise brine shrimp is to set up 5-30 gallon tanks (indoors or outdoors) in a sunny location that will encourage an algae bloom, seed these tanks with freshly hatched Artemia nauplii, and let nature take its course.

Here is how Robert Straughan describes this simple culture method: "Fill the culture container with fresh seawater or salt brine solution and let it age for a week or two in a sunny location. Then add a good hatch of live brine shrimp from your regular hatching jar and if conditions are right, you will soon be a full-fledged brine shrimp grower. In a few weeks, the shrimp will mature and even reproduce in the container. By siphoning off just a portion of the shrimp at a time, you will have a continued supply of this superb food. Green algae will form along the sides of the container and will furnish food for the growing shrimp so that all you will have to do is check the salinity occasionally and add a little freshwater when necessary. About every three or four months, replace about one-fourth of the solution with fresh saltwater and, if all goes well, the growing process will go on indefinitely. If the container is left outside, cover the top partially with a piece of glass so that just a little rain will enter the container during storms. Aeration is helpful where a large quantity is desired, but it is not necessary if clean water is used and the container is not too crowded. Evidently the growing algae gives off oxygen for the author has raised large quantities in the method described above and used neither aeration nor food" (Salt-Water Aquarium in the Home, pp 103-104).

The grow out containers for this low-maintenance method of raising brine shrimp can be buckets, large Rubbermaid vats, or old aquaria, but I find transparent containers work the best for promoting the growth of algae and observing the culture as the brine shrimp grow.

I should point out, however, that you don’t need to grow out the newly hatched brine shrimp in order to raise seahorse fry. In fact, newborn H. erectus have small mouths, and, while they can take the newly hatched brine shrimp as their first food right from birth, they may not be able to eat the brine shrimp that is more than a day or two old, as discussed in more detail below:

Fry Feeding Schedule

When feeding baby brine shrimp (bbs) or Artemia nauplii to seahorse fry, you want to avoid overfeeding (feeding them too much at a single feeding) as well as feeding them newly hatched bbs which have depleted their yolk supply and are nutritionally barren. The best way to do that is provide the fry with many small feedings throughout the course of the day, each of which they can clean up fairly quickly, rather than one or two massive feedings.

I suggest feeding the fry 3-5 times daily, at least 2-3 hours apart. When you are feeding the right amount, the fry should consume most of the nauplii within the first 20-30 minutes, but give them 3 hours to finish the rest and digest it fully before you feed them again. Ideally some brine shrimp will remain throughout each 3-hour feeding session, albeit at a greatly reduced feeding density after the first half-hour.

In other words, your ideal fry feeding schedule should go something like this: 8 AM feed, 11 AM feed, 2 PM feed, 5 PM feed, 8 PM feed, lights out at 11 PM. Harvest the baby brine shrimp for each feeding session in succession from each of the jars you started hatching at 3-hour intervals. This will assure that the Artemia nauplii you are feeding to the fry are no more than 3 hours old and thus at the peak of their nutritional value.

Like all babies, seahorse fry exist only to eat and poop. To say they are voracious is a gross understatement — at this stage of their development, the newborns have but one mission in life: to eat and thus to grow. Researchers have found that a single seahorse only a few weeks old can consume 3000-4000 newly hatched brine shrimp in a single day! Milligram for milligram, a great white sharks feeding habits appear downright dainty and positively anorexic compared to a baby seahorse on the prowl for live prey. And as you can imagine, when well-fed fry eat that much, defecation is amazingly rapid, with each newborn producing an average of one fecal pellet every 25-30 minutes.

One of the many quirks of seahorse anatomy is that they lack a true stomach like ours with the capacity to store food between meals (Bellomy, 1969). Rather, they are endowed with a rudimentary "stomach" that is little more than a pouchlike expansion of their intestine with no distinct separation between it and the rest of their digestive tract (Tamaru, Aug. 2001). Food passes continuously through this simple stomach instead of being stored therein. This is an adaptation to a sedentary lifestyle in which seahorses feed while at rest (as ambush predators that wait for their prey to come to them) more or less continuously throughout the daylight hours, rather than storing food or stockpiling energy in fat reserves (Tamaru, Aug. 2001). And like other carnivorous fishes, their intestinal tract is also relatively short (Tamaru, Aug. 2001).

Therefore, think of their digestive tract as a short continuous tube. When a seahorse is full, nothing more can be taken in at one end of its digestive tract without something being passed out of the other end. Seahorse fry don’t stop eating once they are full — the feeding instinct of these seagoing gluttons is so strong it compels them to keep eating as long as suitable prey is present. Baby seahorses, not sharks, are the ocean’s "remorseless eating machines!"

When they are overfed, particularly on hard-to-process Artemia nauplii, food passes through their system too fast to be digested properly. Because they swallow their prey whole and intact, this can actually reach the absurd point where they are passing live Artemia in their fecal pellets (Warland, 2003)! When that happens they are getting virtually no nourishment from their food and are literally starving in the midst of plenty. Here’s how Tracy Warland, a commercial seahorse farmer in Port Lincoln, Australia, describes this feeding dilemma and how to deal with it:

"We feed by looking closely at the ponies feces under a microscope, (a cheap dissecting microscope is ample); we breed 5 different species and all the ponies are the same, in as much as they are total gluttons. Baby seahorses (ponies) will eat so much instar 2 Artemia that they will pass out live Artemia in their feces, and they will of course not get any nutritional value from any feeds, so by over feeding you will starve them to death. We have done this. So if you feed them too much you will just love them to death as they will starve due to inability to digest. We look at the feces to determine the level of digestion and feed accordingly. Usually a feed is what the biomass of the tank can clean up in a 20-minute session, after which we leave them alone for about 2 hours and then feed them again. As soon as they defecate, we use a pipette to gather up the droppings and examine them under the microscope to check digestion levels and adjust our feeding accordingly. This is not necessary for every feed as you can soon learn the quantity required for each feeding; just make sure that the Artemia is digested fully (Warland, 2003)."

So if you have a microscope, you can easily verify that you are feeding enough but not too much at any given feeding by visual examination of the fry’s fecal pellets. Otherwise, you will eventually learn the right amount to feed and how often to feed from experience. The right feeding regimen varies according to species, the size of the brood and the size of your nursery tanks, as well as the type of food you are providing, so it is difficult to make generalizations in that regard. But Tracy Warland recommends the following:

"You need to add enough food for your fry to eat for about 15-20 minutes (75%
of the food should have been consumed within that time). If it is not, then you have added too much. The fry then should have some time to digest this food, about 2 – 3 hours is plenty. Provide at least 3-5 feedings daily. Only feed during daylight hours and turn off lights at night (Warland, 2003)."

Tracy’s feeding regimen may not be the best option for the home hobbyist, however. The average hobbyist has his hands full just trying to keep up with the demands of a brood of fry, doesn’t have access to a microscope to monitor the fecal pellets of the fry, and generally needs to be far more concerned about underfeeding than overfeeding. The salient point is that when rearing fry, many small feedings daily are vastly preferable to one or two large feedings. Most hobbyists are more successful at rearing when their goal is to assure that the fry have access to at least some food throughout the day. Many breeders accomplish this by adding small amounts of newly hatched Artemia to their nurseries whenever they walk by. For the sake of hygiene and water quality, its important to siphon off the bottom of the nursery tanks between feedings, whether or not you are able to do a microscopic examination of the fecal pellets.

It’s imperative that you work out the most efficient feeding regimen one way or another, since overfeeding is not only bad for the seahorse’s digestion, it also debilitates the fry because it is very energetically demanding for them to pursue prey and eat nonstop all day long (Warland, 2003). With a little experience, you will soon work out the feeding regimen that works best for you.

Many home hobbyists find an alternating 2-hour feeding schedule works well during the day. The fry are allowed to feed for 2 hours, then fasted for 2 hours, then given another feeding and fasted for 2 hours, and so on. The nursery is then darkened overnight and the seahorses are rested.

The general idea is to set up multiple hatching containers so that you can harvest the newly hatched brine shrimp nauplii from a different hatchery for each feeding. Thus, if you’re going to be feeding five times a day (i.e., every three hours throughout the day), then you would set up a battery of five separate brine shrimp hatcheries, and you would start the brine shrimp cysts hatching in each of them at three hour intervals.

The reason you stagger the hatching jars that way, adding the eggs to each at three hour intervals, is to assure that you are feeding the fry newly-hatched Artemia nauplii that have just emerged from their eggs, and therefore are at the peak of their nutritional value, for each of the feedings. Right after the first instar Artemia nauplii have emerged from their shells, their yolk supply is completely intact and they are more nutritious, since when the seahorse fry eat them, they get the benefit of all the nutrients in the rich yolk supply. Several hours after the Artemia nauplii have hatched out, they will have consumed much of their yolk supply and have relatively little nutritional value as a result. So it is very desirable to feed the newborns seahorse fry first-instar Artemia nauplii that have just emerged from their shells, because the nauplii are the smallest at that stage and therefore the easiest for even the undersized fry (i.e., runts) to swallow and more importantly because the newly emerged nauplii retain their maximum nutritional value at that point.

Once the Artemia nauplii undergo their first molt and becomes second-instar nauplii, they have exhausted their yolk supply and develop mouthparts so they can begin feeding on their own. Baby brine shrimp at this stage are larger and and may be too large for the smallest newborns to eat, and the second-instar bbs must be fed or enriched (i.e., gut-loaded) at this stage or they have very poor nutritional value. So the idea is to assure that you are always feeding the newborn seahorses first-instar Artemia nauplii that have just hatched and retain their full supply of yolk.

That’s why it’s important to stagger the start of the hatch in each of the hatcheries. If you started the brine shrimp hatching at the same time in all five of the hatcheries, by the time you did your second feeding of the day, some of the brine shrimp would be three hours old. Likewise, some of the brine shrimp you fed for the third feeding would be six hours old, and some of the brine shrimp you offered at the fourth feeding that day would already be nine hours old, and so on. The older brine shrimp nauplii would have used up more and more of their yolk supply, or already entered the second-instar phase before they were fed to your seahorses, and not have been nearly as nutritious as the brine shrimp you offered for the first feeding that day.

Staggering the start of the hatch in each of the hatching containers therefore allows you to offer primarily newly-hatched first-instar Artemia nauplii with complete yolk supplies at each of the feedings throughout the day. In other words, for the first feeding of the day, you harvest the Artemia nauplii from the hatchery you started first. You harvest the nauplii for your second feeding from the hatching jar you started hatching three hours later, and you harvest the nauplii for the third feeding from the hatchery you added the Artemia cysts to six hours later, and so on.

In short, if you will be feeding your seahorse fry five times a day, your ideal fry feeding schedule should go something like this: 8 AM feed, 11 AM feed, 2 PM feed, 5 PM feed, 8 PM feed, lights out at 11 PM. Harvest the baby brine shrimp for each feeding session in succession from each of the jars you started hatching at 3-hour intervals. This will assure that the Artemia nauplii you are feeding to the fry are no more than 3 hours old and thus at the peak of their nutritional value.

Let me know if your male continues to show signs of an advancing pregnancy, Harry, and I have a lot of other information on rearing H. erectus I would be happy to share with you off list (the files are too large to post here). When the big moment draws near, you can contact me at the following email address for the additional info: [email protected]

Best of luck with your seahorses and their future progeny, Harry!

Happy Trails!
Pete Giwojna