Re:Dwarf Seahorse Feeding?

Pete Giwojna

Dear Tracia:

Welcome to the forum!

It sounds like you’ve been doing a fine job of taking care of those dwarf seahorses (Hippocampus zostrae) in your marine biology class, and that they are responding to your TLC with a healthy interest in courtship and breeding.

Congratulations on witnessing one of the males delivering his brood of young! 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!

I am familiar with the conical brine shrimp hatcheries and they do a good job of hatching out the Artemia nauplii. Separating the brine shrimp from the empty egg shells is an important task and can be a chore no matter what type of hatchery you are using. I find that the easiest way to deal with that problem is to use decapsulated eggs so that there are no shells to deal with afterwards.

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.

You can buy decapsulated brine shrimp eggs but they are considerably more expensive than the ordinary Artemia cysts, and for this reason, most seahorse keepers prefer to buy the economical ordinary Artemia cysts and then decapsulate the eggs themselves. You can easily decapsulate your own brine shrimp eggs at home, as explained below.

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


1. Pour yourdetoxified/dechlorinated freshwater into a container and clip an 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. (This step will hydrate the brine shrimp cysts.)

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.

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

Since you are looking after the dwarf seahorses in your marine biology class and it may not be practical for you to decapsulate the brine shrimp eggs under the circumstances, you can also use light to help separate the newly hatched brine shrimp from the empty egg shells, as described below:

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 hatching container by darkening the room and shining a flashlight on the middle of the container. The newly hatched brine shrimp will congregate where the light is the brightest, away from the floating egg shells at the top and away from the unhatched eggs at the bottom. (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.

Those small anemones you noticed are Aptasia rock anemones and you did well to remove them promptly, since their sting can be deadly to the baby seahorses and harmful to the adult dwarfs. As long as you are able to physically remove the anemones, whole and intact, that can be an effective means of controlling them. But you have to take care when removing them since they can sometimes spread by fragmentation. Aiptasia rock anemones can easily be killed by injecting them with a number of solutions — Kalkwasser, boiling water, lemon juice, a number of commercial products, such as Joe’s Juice, and that’s another easy way to eliminate them from a small aquarium.

Be sure to keep a close eye out for hydroid colonies as well, Tracia. If Aptasia rock anemones have appeared in the dwarf seahorse tank, there is a good chance that hydroids could also begin to colonize the aquarium.

If you haven’t already done so, I would also suggest that you pick up a copy of Alisa Abbott’s guidebook titled Complete Guide to Dwarf Seahorses in the Aquarium. That’s one book every Pixie owner and dwarf seahorse keeper should have on hand. I’ve proofed Alisa’s dwarf seahorse book for TFH publications and wrote the preface for it, and I highly recommend it! You can order a copy from Ocean Rider are any of the major booksellers.

If you do a search on this forum you can find a lot more useful information on the care and keeping of dwarf seahorses right at your fingertips, Tracia. There is a rectangular window in the upper right-hand corner (just above the page numbers) on the forum with the words "search forum" in it. Just type the word or phrase you are looking for into that window and press "Enter" on your keyboard, and the results of your search will pop up in just a few moments. For example, if you type in "Pixies" or “dwarf seahorses” or "Hippocampus zostrae," you’ll find some detailed discussions explaining more about the aquarium requirements, feeding, and rearing of these pint-size pigmy ponies.

Best of luck with the dwarf seahorse tank and your course in marine biology, Tracia! Keep up the good work!

Happy Trails!
Pete Giwojna

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