Re:Unexpected Babies

#3180
Pete Giwojna
Guest

Dear Kim:

Congratulations on your first brood of babies! I’d be happy to provide some basic information on setting up a nursery tank for rearing pelagic fry like Mustangs (Hippocampus erectus).

Don’t panic — the fry are born with a limited yolk supply that can sustain them for the first 24 hours, so they needn’t be fed immediately and that gives you a little time to get your brine shrimp hatcheries going, as I’ll explain in greater detail below.

Did you get to see the male giving birth, Kim? That’s one of the most amazing spectacles in all of nature! The male’s brood pouch or marsupium enfolds, protects, aerates, osmoregulates, and nourishes the developing embryos as the stallion undergoes a true pregnancy (Vincent, 1990). The gestation period in Hippocampus erectus lasts anywhere from 14-30 days depending on water temperature and a number of other factors (Vincent, 1990). The volume of the pouch increases dramatically as the pregnancy progresses. A male that is carrying a significant number of young becomes very rotund so that only a very thin layer of epithelium and connective tissue separates the interior of the pouch from the outside world by the time birth is imminent (Vincent, 1990).

The fully developed young emerge from their individual compartments and shake loose into the lumen of the pouch prior to birth (Vincent, 1990). They become very active toward the end of the pregnancy and can sometimes be seen wriggling about through the membrane of the swollen brood pouch. This appears to be every bit as uncomfortable as it sounds, since expecting males become agitated and distressed as the big moment approaches. They experience definite labor pains when birth is imminent, evident as a series of powerful contractions, and soon begin pumping in time with these birth spasms in order to forcibly eject the fry from their pouches. Labor usually begins well after dark in the early morning hours (Vincent, 1990). The distraught male may pump and thrust vigorously for hours before finally ejecting the first of the newborns (Vincent, 1990). The fry are expelled singly or in ones and twos at first, but are soon spewing forth in bunches and bursts of a half dozen or more.

Delivering a large brood this way is hard work, and the exhausted male will pause periodically to recover from his exertions, gathering his strength until he is caught in the throes of another round of contractions. In some cases, it takes 2-3 days for the entire brood to be delivered in this manner.

No matter how often I see a male giving birth, it never ceases to amaze me. Watching the fry erupt into existence that way is an incredible sight. They are perfect miniature replicas of their parents, able to fend for themselves from the first. It seems a brutal beginning, a ruthlessly rude awakening, to be violently thrust into the world in such an abrupt fashion, but the newborns hit the water swimming without missing a stroke. It’s a thrill to be witnessing such a miracle of nature and always leaves me awed and exhilarated!

All seahorse babies are challenging to raise and your Hippocampus erectus are no exception, Kim. How difficult or challenging they may be depends on the type of seahorses you have. Two main factors determine how easy or hard seahorse fry are to raise: (1) their size at birth and (2) whether or not they undergo a prolonged pelagic phase. The bigger and better developed the newborns are, the easier they are to raise. Seahorse fry whose average length at birth is 10 mm (0.4 inches) or more are able to take enriched Artemia as their first foods and are relatively easy to rear. Seahorse fry that are significantly smaller than 10 mm (0.4 inches) at birth need to be started on smaller foods that are more difficult to provide in copious amounts on a daily basis, such as rotifers, copepods, and larval Mysis, making them more difficult to raise. Likewise, seahorse fry that undergo an extended pelagic phase, during which they drift freely with the plankton, are much more troublesome to raise than benthic seahorse fry, which orient to the substrate and seek out hitching posts straightaway. The pelagic fry are difficult because the surface huggers tend to gulp air and suffer fatal buoyancy problems, and may even become entrapped by surface tension. As a result, most hobbyists find that mortality is very high during the pelagic phase.

The easiest seahorse fry to rear are therefore benthic fry that are large and well developed at birth. Dwarf seahorses or Pixies (Hippocampus zosterae) fall into this category, and indeed many hobbyists have closed the life cycle with zosterae. The most difficult seahorse fry to raise are relatively small and underdeveloped at birth, and must pass through a lengthy pelagic stage. Brazilian seahorse fry (Hippocampus reidi) are a good example of this category, and are notoriously difficult to raise.

Ocean Riders span the gamut in that regard, including both those species that are the easiest of all to raise and those that are the most difficult to rear, and everything in between. At the one extreme, there are Mo’Olios, which produce very large broods of tiny fry that are barely 3-4 mm at birth and remain pelagic all their lives, even as adults. Mo’Olios are very challenging for even expert aquaculturists with state-of-the-art facilities to raise. Brazileros and Gigantes likewise have enormous broods of relatively small (6-7 mm) fry that undergo a rather protracted pelagic phase lasting weeks. The average hobbyist would still be hard-pressed to regularly raise any of their fry.

At the other extreme, there are Pixies, which produce small broods of large, well-developed benthic fry that hitch from day one. Pixies are probably the easiest seahorses to rear, and no doubt more hobbyists have closed the life cycle with this species than all other seahorses combined. Most of the remaining Ocean Rider types (Mustangs, Sunbursts, Pintos, Fire Reds) produce fry that are fairly good sized (about 8-10 mm) and whose pelagic phase is fairly short (several days rather than weeks), and which are therefore intermediate in difficulty.

In short, Kim, your Mustangs (H. erectus) will produce fry that are moderately difficult to raise. They will be able to eat newly hatched brine shrimp right away, but they will go through a pelagic phase lasting anywhere from several days to a week or two. The link below will take you to an article that discusses how to rear them in greater detail (they are suitable for the "easy" rearing method outlined in the article). It will explain how to set up a basic nursery tank and culture the live foods you need to feed the newborns:

Click here: Seahorse.com – Seahorse, Sea Life, Marine Life, Aquafarm Sales, Feeds and Accessories – Nutrition – Feeding & Rearing the Fry
<http://www.seahorse.com/FAMA_-_Freshwater_and_Marine_Aquarium_magazine/Horse_Forum_-_Nutrition/Nutrition_-_Feeding_%26_Rearing_the_Fry_-_Part_IV/&gt;

For starters, here are some tips on hatching and enriching the baby brine shrimp you’ll need to feed the newborns, Kim:

Hatching Out Brine Shrimp (Artemia)

Many commercially made hatcheries are available or you can easily improvise your own from 2-liter soda pop bottles or quart jars. Fill the jars or bottles about 4/5 full with saltwater or brine solution and equip each container with an airstone connected to a length of rigid airline tubing that reaches all the way to the bottom. An inexpensive vibrator air pump with a set of gang valves with put out enough air for the entire battery of hatching containers. Add 1/8-1/4 teaspoon of brine shrimp eggs to each container and adjust the valves so the airstones bubble vigorously, keeping the eggs in suspension at all times. Shine a light directly on the hatching bottles and keep them illuminated 24 hours a day. A temperature of 80-82 degrees F is optimum for hatching brine shrimp.

The eggs will begin hatching after 1-24 hours, and the emerging nauplii should be harvested and used as soon as possible after incubation while they still retain their full nutritional value. (The yolk supply lasts about 6-8 hours after hatching, and the food value of the nauplii deteriorates steadily as the yolk sac is consumed. Once it has been exhausted after about 8 hours, the nutritional worth of the nauplii drops drastically.)

However, before they can be used as food, the nauplii must first be separated from the indigestible egg shells. Otherwise the empty shells may be accidentally ingested by the seahorse fry, which has been known to cause intestinal blockages and death.

The brine shrimp nauplii can be separated from the eggs simply by turning off the air for a few minutes and allowing the water to settle. The unhatched eggs will sink to the bottom of the hatching jar while the empty egg shells will float to the top. The nauplii can then be concentrated in the center of the jar by darkening the room and shining a flashlight on the jar’s midsection. (Brine shrimp are attracted to light and will be drawn together in midwater where the light is focused.) Harvest the nauplii by using a siphon or turkey baster to suck up the concentrated mass of shrimp. The shrimp-laden water can then be strained through a plankton screen or fine-meshed brine shrimp net.

Return the strained water to the hatching container, add more eggs, and readjust the aeration. The same hatching solution can be used for a week’s worth of hatchings before it has to be replaced.

Alternating the hatching container from which you harvest each day’s supply of nauplii will assure that you have a nonstop supply of newly hatched brine shrimp available at all times.

If you’re still uncertain about how to proceed, the information at the following link should make everything perfectly clear:

Click here: Brine Shrimp Technical Information 1
http://www.brineshrimpdirect.com/brineshrimpdirect-faq-1-2-13.html#hatching

The best eggs or cysts to use for your brine shrimp factory are decapsulated eggs which have had their hard, outer shells stripped away. These shell-less eggs have many advantages over ordinary Artemia cysts. For starters, they simplify the task of separating the live nauplii from the unhatched eggs, since there are no empty shells, and the decapsulated eggs eliminate the possibility of clogged intestines due to the indigestible cysts. Secondly, the decapsulation process destroys virtually all known pathogenic organisms. Since the shell-less eggs have been disinfected, there is much less risk of introducing disease or parasites to the aquarium when you feed your seahorses with brine shrimp from decapsulated cysts. More importantly, the nauplii produced from decapsulated eggs have greater caloric value than the nauplii from unaltered cysts. This is because the nauplii from decapsulated eggs do not have to waste energy struggling to break free of their shells, and thus emerge with 20% greater food value, primarily in the form of additional amino acids and essential fatty acids. This extra nutritional value can make a crucial difference to the rapidly growing seahorses.

Decapsulated brine shrimp eggs are now available from some manufacturers. Although the shell-less eggs are expensive to buy, it is easy for the serious hobbyist to decapsulate his own brine shrimp eggs at home.

Decapsulating Brine Shrimp Eggs.

Decapsulating brine shrimp cysts — the process of dissolving away their hard outer shell — may sound intimidating at first and may seem awkward when you first attempt it. No doubt you will have these instructions open, your eyes glued to the page, with all of your supplies at the ready the first few times you perform this procedure. Relax, this is not difficult at all, and after you’ve done it a couple of times, you will see how truly easy it is and realize decapping is well worth the extra few steps. I will walk you through each numbered step. Measurements do not have to be exact. Regular strength bleach is best, but ultra bleach can be used at lesser portions. You can estimate this yourself. Decapsulating your cysts is beneficial for a number of reasons:

· Reduces the risk of hydroids.
· Removes the outer shell, which means less mess and no fouling of your tank.
· Eliminates intestinal blockages from accidental ingestion of indigestible shells.
· Kills off any and all unwanted contaminants.
· Slightly quicker hatching times.
· Better hatch rates.
· Increased nutritional value secondary to less energy expenditure during hatching.

Supplies Needed for Decapsulating:

· Brine shrimp net
· Air pump
· plastic clip or paper clip wrapped in baggie to clip airline into the container
· Approximately 2 teaspoons brine cysts.
· Approximately 2/3 cup of bleach
· Approximately 2 cups of water

Procedure:

1. Pour your water into a container and clip airline tubing to the side. (No air stone is needed for this). This will keep the cysts in motion. Allow the cysts to aerate this way for approximately 1 hour or a little more.

2. Add in your bleach and continue aerating. As the outer shell gradually dissolves, the eggs go through a series of color changes from brown to gray to white and finally to orange–the color of the nauplii within. This process takes about 7 minutes. The decapsulation process is complete when your cysts become an orange-yellowish color.

3. Pour decapsulated eggs into a brine shrimp net. Add a dechlorination product if you want and rinse until you no longer smell bleach.

4. Drop eggs into your hatching container. You can also refrigerate eggs for about 1 week prior to use in a supersaturated saline solution.

You will need to either feed the bbs to your seahorses immediately after hatching, when their yolk supply is virtually intact and they have their maximum nutritional value, or feed bbs that are 2-days old or older and have been enriched prior to feeding.

Enriching Brine Shrimp at Advanced Instars

Feeding baby brine shrimp his the key to raising nutritious nauplii for your juvenile seahorses. Newly hatched brine shrimp deplete their yolk supply within 6-8 hours and must be fed regularly thereafter to maintain their food value.

Fortunately, brine shrimp are filter feeders and will take in whatever is suspended in water with them. This makes it easy for the aquarist to load the shrimp he is raising with nutritional value by giving them a healthy diet supplemented with special food additives. Commonly used foods for culturing Artemia include unicellular algae; rotifers; yeast-based emulsions; micronized egg yolk, rice bran, wheat flour or whey; and dried Spirulina algae.

Research has proven that brine shrimp can be further enriched by adding supplements such as cuttlefish liver oil, cod liver oil, corn oil, fat-soluble vitamins, amino acids, and mineral formulations to their culture water. Analysis of the nutritional content of culture animals after they had been exposed to such supplemental additives showed a dramatic increase in long-chain fatty acids and many vitamins.

Rather than experimenting with your own concoctions, I recommend using one or more of the lipid-rich food concentrates which have recently been developed specifically for use in aquaculture. Products commonly used by professional breeders for fortifying brine shrimp nauplii include Beta Meal, amino acid and essential vitamins (liquid multi-vitamins), commercial products of (W3) highly unsaturated fatty acids such as Vibrance 1, Selcon Concentrate, Selco, Culture HUFA, Roti-Rich, Astaxanthene biological pigment Natu-Rose, AlgaMac 2000, MicroMac 70, and unicellular microalgae cultures (e.g., T-iso, T-weiss, and Nannochloropsis, Chlorella and Isochrysis sp.). Such products are typically rich in amino acids, highly unsaturated fatty acids (HUFA) and vitamins, which makes them ideal supplements for culturing Artemia. Very often, using a combination of these enrichment products provides better nutrition and produces better results that relying on any one product alone.

For best results, 24 hours after the culture tanks are seeded with newly hatched brine shrimp, begin feeding the nauplii sparingly by adding a concentrated food supplement or enrichment formula according to the instructions. Adjust the amount so that a slight haze barely clouds the water for a few hours every day. Do not feed again until the water is crystal clear and do not overfeed. As the brine shrimp grow, you may need to adjust the dosage of your favorite enrichment product by either increasing the frequency or the amount of the feedings.

The best way to harvest the enriched nauplii is to use a plankton collector or strain the culture water through a plankton screen (available from Florida Aqua Farms). As your seahorses grow, you can sift the nauplii through plankton screens with progressively larger mesh, selecting only the shrimp that are at just the right stage of development for the size of your juveniles.

Don’t worry about decapsulating your brine shrimp eggs or Artemia cysts for now, Ashley. Just get your hatchery going with ordinary brine shrimp eggs or cysts so you can have a suitable food to feed the fry as soon as possible.

Once you get your brine shrimp hatcheries cranked up and running in high gear, you’ll need to maintain frequent feedings in order for the newborns to do well. I’ve outlined the recommended fry feeding schedule for you below, which is based on Tracy Warland’s fry feeding regimen as a professional breeder. When looking over these recommendations, bear in mind that the home hobbyist almost always needs to be more concerned about underfeeding than overfeeding (it’s ordinarily only the pros that worry they might be feeding their fry too much). The humble home breeder will have his or her hands full just trying to keep up with the endless appetites of all those fry.

With that in mind, here are some suggestions and information to serve as guidelines when getting your rearing program started.

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.

Okay, Kim, that should give you a pretty good idea of what you should shoot for when raising the newborns. Also, you should be aware mated pairs of Sunbursts and Mustangs (Hippocampus erectus) typically remate within a day or two after the male has delivered his latest brood, so keep an eye on your seahorses for signs of courtship and mating the next couple of days — you don’t want to miss the amazing love dance of the seahorse and their fascinating courtship displays.

Best of luck with your new seahorses and their fry, Kim!

Happy Trails!
Pete Giwojna


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