Re:raising pixies and Zulus

#3186
Pete Giwojna
Guest

Dear SF:

Well, it sounds like you are doing a lot of things right when it comes to rearing, but I do have a couple of suggestions to offer.

If hydroids are not an issue, then I suspect the gradual die off beginning around the 10th day may reflect nutritional deficiencies, particularly if the fry did not appear to be growing. In that case, I would suggest using decapsulated Artemia cysts, which can boost the nutritional value of the Artemia nauplii by as much as 20%, or enriching the nauplii before you feed the fry, as discussed below:

Decapsulation

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 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

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.

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

Once you get the hang of it, decapping brine shrimp cysts is really quite easy, SF, and if your losses were due to either inadequate nourishment or intestinal blockages from accidentally ingesting the indigestible shells, decapsulation may make a big difference when rearing your next brood.

For best results, 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 in such as Vibrance I (i.e., the original Vibrance). Other 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.

Fortifying 1st-instar Artemia Nauplii (newly hatched baby brine shrimp)

Artemia nauplii (baby brine shrimp) are filter feeders that will ingest whatever is suspended in the water with them. This makes it easy to enrich the nauplii with everything from yeast cells to microalgae to fatty acids and vitamins and minerals as discussed above, greatly enhancing their nutritional profile in the process.

The problem with such traditional enrichment methods is that only older nauplii at advanced stages of development can be fortified this way. Newly hatched brine shrimp nauplii (1st instar) lack mouthparts and derive their nourishment from a yolk sac. They are incapable of ingesting particles in the water. Consequently, only bigger nauplii that have molted once or twice (2nd instar and beyond) are suitable for this type of enrichment. This is a serious drawback since these older, larger Artemia nauplii have already grown beyond the size that most newborn seahorse fry are capable of swallowing.

Hobbyists with seahorse fry that are unable to take 2nd-instar Artemia nauplii as their first food usually get around this problem by offering newly hatched brine shrimp nauplii obtained from decapsulated cysts. These 1st-instar Artemia nauplii are fed to the fry as soon as possible after hatching while the baby brine shrimp still retain as much of their yolk sac as possible.

However, there is a better alternative that combines the best of both techniques, making it possible to provide seahorse fry with bite-sized, enriched Artemia nauplii that contain most of their yolk supply. This is accomplished by decapsulating Artemia cysts and refrigerating the newly hatched brine shrimp at a temperature of 41-45 F (5-7 C) for 24-36 hours when the nauplii are still between 12-16 hours old (Mai 2004b). Cooling down the nauplii to such temperatures slows down their growth and metabolism to a virtually standstill, and they can then be enriched continually for the next 2 or 3 days while they remain in a state of arrested development (Mai 2004b). They will not grow or molt during this period, keeping the Artemia bite-sized and allowing the inactive nauplii to retain the bulk of their yolk as they undergo enrichment (Mai 2004b). Supplements rich in high unsaturated fatty acids (HUFA) and vitamins and minerals are typically used to fortify the refrigerated nauplii (Mai 2004b).

Although the Artemia nauplii do not and cannot actively feed while in this state of suspended animation, the prolonged period of immersion in this nutrient soup allows them to gradually absorb the enrichment nonetheless (Mai 2004b). Whether the concentrated nutrients slowly infuse their bodies or merely coat the nauplii or both is uncertain, but there is no doubt about the superior results this method of enrichment can produce (Mai 2004b).

Rolf Hebbinghaus was one of the first to develop the refrigeration method of fortifying Artemia nauplii at the Lubbecke-Aquazoo in Dusselfdorf, Germany (Mai 2004b). Wolfgang Mai has since conducted a series of tests on H. fuscus fry, which demonstrated that the young receiving the enriched Artemia enjoyed significant advantages in length, girth and vigor compared to the control group of fry which received newly hatched brine shrimp nauplii that had not been enriched (Mai 2004b).

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.

So if your fry were not growing and failed to thrive when fed three times daily, SF, you might also consider increasing the number of feedings you offer to ensure that they receive adequate nourishment. 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.

Another possibility is that degrading water quality began to take a toll on the fry over time, SF. I would suggest eliminating the substrate in your nursery tank and performing at least two small partial water changes daily, during which you siphon the bottom of the nursery tank clean of fecal pellets and dead or dying baby brine shrimp.

Since nursery tanks have limited filtration, daily water changes are needed in most systems to maintain water quality and keep up with the metabolic wastes and oxygen demands of several dozen baby sea horses and the thousands of brine shrimp needed to feed them (Giwojna, Jan. 1997). When the fry are well fed, defecation is amazingly rapid, with each newborn producing an average of one fecal pellet every 25-30 minutes (Herald and Rakowicz, 1951). The best way to perform the necessary maintenance is to use a length of airline tubing to siphon off the bottom of the nursery tanks a minimum of twice a day (morning and evening are ideal for this; Giwojna, Jan. 1997). Replace the water that was removed while siphoning with freshly mixed saltwater that has been pre-adjusted to the same temperature, pH and salinity as the rearing tank. Change about 10-20% of the water each time you siphon the bottom, so that a total of at least 25-50% of the water in the nursery tanks is exchanged every day (Giwojna, Jan. 1997). A bare glass bottom facilitates this daily maintenance and makes it easier to maintain good water quality in the nursery.

One final suggestion, SF — pick up a copy of Alisa Wagner Abbott’s outstanding new book on dwarf seahorses (The Complete Guide to Dwarf Seahorses in the Aquarium, 2003, 144 pages), if you don’t already have one. It’s the only aquarist’s guidebook ever to be devoted entirely to dwarf seahorses. It includes excellent, up-to-date information, on every aspect of their care and keeping, including breeding and rearing, population dynamics, and maintaining a self-sustaining colony. All in all, a wonderful resource for the dwarf seahorse keeper, which will answer most of your questions about keeping and rearing these miniature marvels. It’s available from the Ocean Rider site or all of the major book dealers.

Best of luck raising your next batch of fry, SF! Eventually you will work out the feeding regimen and rearing protocols that work best for you and have increasing success with each new batch of fry.

Respectfully,
Pete Giwojna


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