Help with frozen training?

Dear Suzanne:

Congratulations on the two batches of babies and your success rearing them thus far!

You might have better luck weaning the group of juveniles that have been raised on copepods onto frozen Cyclop-eeze (not the freeze-dried kind) rather than frozen bbs. As its name suggests, the Cyclop-eeze is made from cyclopoid copepods and it may therefore have the right order and taste to attract the interest of the youngsters that are accustomed to eating copepods.

The current thinking is that the fry can remain on a steady diet of newly hatched Artemia or copepod larvae until you are ready to begin weaning them onto a diet of frozen foods (usually minced Mysids and/or Cyclop-eeze). Aquaculturists are now converting the fry to frozen foods earlier than ever, often beginning around 3-4 weeks old. Jeff Mitchell reports that the fry are healthier and grow faster the sooner they make the transition to enriched frozen foods, and he expects the young seahorses to have made the transition to frozen foods by the age of 4-1/2 weeks.

The best way to prepare the Mysis for this is to mince the frozen Mysis coarsely rather than putting it through a blender. How fine or coarse you need to chop it depends on the size of your fry, since you want to wind up with bite-size pieces of Mysis. Initially, many breeders prefer to shave small pieces of Mysis off of a cube while it’s still frozen.

When the fry have grown a little larger and can accommodate bigger pieces of Mysis, I find it convenient to carefully thaw whole Mysis individually and then carefully chop them into several pieces.

Either way, it is very important to be extra diligent about vacuuming up leftovers (and any fecal pellets) while the fry are making the transition to frozen Mysis or frozen Cyclop-eeze. Otherwise, the frozen food that doesn’t get eaten right away while it’s still suspended in the water column or shortly after it has settled on the bottom will begin to degrade the water quality in your nursery tank.

It’s important to overlap the fry food when they are making the transition. Offer them shaved or minced Mysis along with the newly hatched brine shrimp they are accustomed to eating or frozen Cyclop-eeze intermingled with live copepods. (Many times it’s better to offer the minced Mysis first, while the fry are still the hungriest, and then add the baby brine shrimp.) Once they begin eating the bits of frozen Mysis well, gradually increase the amount of minced Mysis and decreased the amount of baby brine shrimp you offer at every feeding until they are finally eating the shaved Mysis almost entirely.

Overlapping the feedings this way, offering newly-hatched brine shrimp as usual along with just a little frozen Mysis at first, assures that there is familiar food available to the fry while they are making the transition and makes sure that the slow learners still get enough to eat.

Some hobbyists find it helpful to begin soaking the newly hatched brine shrimp in Mysis juice for a week or two before they actually began offering the bits of minced Mysis along with the bbs. That way, the juveniles get used to the scent of the frozen Mysis and associate it with food before you start to add the bits of frozen Mysis.

Here’s a previous post from Patti that describes how she weaned her erectus fry onto frozen to Hikari Mysis:

[open quote]
I’m wondering if nutrition is your problem.
Could you train them onto frozen mysis? My 4 week old erectus are
eating shaved Hikari frozen mysis already. They started not eating
much of the BBS and looking around the bottom of the bowl. I
enriched the shaved mysis w/Vibrance & put it in the bowl. It goes
to the bottom and they’re on the hunt. They’ll look at it a good
while and then snick. It only took 1 day to train them. I swish it
around a little at first to get them interested.

I think the mysis is better for them nutritionally and they don’t
have to spend so much energy eating all those tiny BBS. Give it a
try. It may take a few days. I gave mine the mysis 1st – before
adding the BBS. That way they were pretty hungry. Then I gave them
some BBS for desert to make sure each one got something to eat if
they weren’t eating enough mysis yet.
Patti [close quote]

Notice that Patti’s erectus fry were all hitching and beginning to look around on the bottom for things to eat, indicating that they were ready to give up their planktonic existence (the high-risk pelagic phase) and make the transition from live brine shrimp suspended in the water column to frozen foods.

When the newborns are the right age, don’t hesitate to try them on frozen Cyclop-Eze first if you aren’t having any luck with the frozen Mysis. Lelia Taylor is one hobbyist who has had good results using the Cyclop-Eze, as she described below:

<open quote>
I have had success placing BBS in cyclop-ez, then feeding the mixture to my babies. They readily take the cyclop-eze. As they get bigger I add frozen, enriched brine shrimp. they began eating the frozen food immediately. Using the same principle, I began adding Mysid shrimp, along with the brine shrimp and cyclop-ez. I have found, even very young babies, will pick the larger pieces of Mysid shrimp, into bite sized pieces. I have also had success culturing copepods in my baby and grow up tanks. The babies readily feed on these, as well. <close quote>

Just be patient and persistent, Suzanne, and sooner or later your efforts should pay off and most of the fry will make the transition from live Artemia nauplii to frozen foods successfully. As we have already discussed, shaved frozen Mysis and frozen Cyclop-Eze produce the best results for most home hobbyists when they are weaning Mustang and Sunburst (Hippocampus erectus) fry.

The bars of frozen Cyclop-Eze work especially well for this because they will shed copious amounts of the bite-size frozen cyclops. The frozen Mysis that works best for most hobbyists is Hikari in frozen blocks rather than trays. The Hikari Mysis is much smaller than Piscine Energetics Mysis relicta and that makes it easier to shave off bite-sized pieces for the young seahorses.

When it comes to shaving the Mysis, a technique that works well for many home hobbyists is to use a potato peeler to shave off bits of the Hikari Mysis from a frozen block, and then use a single edged razor blade to further mince the frozen bits the potato peeler has removed.

Try offering the minced Mysis exclusively for their first feeding of the day when the youngsters are the hungriest. Watch the juveniles closely to see if any of them begin to pick pick at the minced Mysis or pick it up from the bottom. If they still aren’t having any of it, siphon up the uneaten frozen Mysis after about half an hour and offer them newly hatched brine shrimp soaked in Mysis juice so that they have something to eat, and intermingle some freshly minced Hikari frozen Mysis or Cyclop-Eze in with the bbs.

Periodically repeat the above procedure and all should go well. In the meantime, newly hatched Art Amaya nauplii or copepod larvae should be adequate to keep the seahorse fry healthy and growing.

Bonus tip: adding one or two older juveniles that are already eating the frozen Mysis well to the nursery tank along with with the inexperienced fry in order to act as their mentors can hasten the transition. Many hobbyists report that fry learn to take frozen minced mysids much faster and easier when they are provided with teachers to show them the way. These teachers are usually a few of the older fry from a previous brood, which have already become proficient at feeding on the frozen mysids (Liisa Coit, pers. com.). The younger fry are quick to copy them, learning from their example.

Best of luck keeping up with the endless appetites of your remaining fry and weaning them onto frozen foods, Suzanne!

Happy Trails!
Pete Giwojna

Dear Suzanne:

Yes, indeed — if you can possibly provide them in suitable amounts, copepods are by far the best first foods for seahorse fry. Research shows that they are a natural prey item that constitutes a large proportion of the diet of pelagic seahorse fry in the wild. As such, the copepods are much easier for newborns to digest than newly-hatched brine shrimp, which have been removed from the marine environment by several million years of evolution. In addition, the copepods are much more nutritious with higher levels of highly unsaturated fatty acids and other lipids. Several studies demonstrate that seahorse fry grow faster and have improve survivorship when they are fed on copepods versus Artemia nauplii.

Best of all, research indicates that the newborns only need to be provided with copepods for about the first week of life (4-7 days) in order to achieve these benefits (Todd Gardner, pers. com.). After that, the newborns have grown enough and their digestive tracts have matured enough to be able to handle newly-hatched brine shrimp without difficulty and Artemia nauplii can serve as the staple diet for the fry thereafter.

In short, Suzanne, there is now considerable evidence that indicates copepods are a superior food source for newborn seahorses. In a nutshell, the copepods are simply far more nourishing and easier for the fry to digest than Artemia.

For example, here are the abstracts from a couple of the recent studies on rearing seahorse fry with copepods that will give you a better idea of what I’m talking about (I would be happy to e-mail you copies of the complete studies off list if you’re interested):

Rearing West Australian seahorse, Hippocampus subelongatus, juveniles on copepod nauplii and enriched Artemia
M.F. Payne), R.J. Rippingale
School of EnÍironmental Biology Curtin University of Technology, GPO Box U1987,
Perth 6845, Western Australia
Received 3 November 1999; received in revised form 31 January 2000; accepted 31 January 2000

Abstract
Improved captive breeding techniques are required for seahorses. Artemia nauplii are generally considered a poor first feeding diet for many seahorse species. This study compared growth and survival of newborn Hippocampus subelongatus reared on cultured copepod nauplii and Artemia nauplii enriched with Super Selcow. Early growth and survival of seahorses were significantly greater when fed copepod nauplii. Copepod nauplii were well digested by juvenile seahorses whereas Artemia nauplii were not. Fatty acid requirements of seahorses could not be determined.

The addition of UV water sterilization improved seahorse survival. When offered copepod nauplii of different sizes, 5-day-old seahorses preferentially selected the largest nauplii. Maximum predation rate in these juveniles was 214 copepod nauplii/seahorse. Provision of copepod nauplii to juveniles improves the prospects of establishing captive breeding populations of H. subelongatus. q2000 Elsevier Science B.V. All rights reserved.
Keywords: Seahorse; Copepod; Artemia; First feeding; HUFA; Prey selection

And from Robin James, Weymouth Bioservices

Effect of copepod diet on growth rate of juvenile Hippocampus abdominalis.

Introduction:
Artemia is commonly fed to juvenile sea-horses as it is cheap and easy to culture. However, it is known to have a low nutritional value and is thought to be unsuitable for the delicate digestive systems of the juveniles. Copepods are smaller, more nutritious and less abrasive, but difficult to culture and more expensive than Artemia. This trial aims to asses whether a copepod enriched diet produces an improved growth rate of newborn H. abdominalis when compared to the growth rate produced by a standard Artemia diet.

This study produce much the same results — copepods proved to be more nutritious and resulted in faster growth and lower mortalities than newly-hatched brine shrimp. A number of other studies have since demonstrated the same thing.

So it’s not surprising that the fry that receive the copepods are doing the best in your case, Suzanne. By all means, continue to provide this most nutritious live prey for your seahorse fry if you can manage it. Once they make it past the first week of life, you can then switch them on to newly-hatched Artemia nauplii as their staple diet without any ill effects.

Best of luck raising your juveniles the rest of the way, Suzanne!

Happy Trails!
Pete Giwojna

Dear Suzanne:

You bet, I’d be very happy to e-mail you copies of those studies. Just contact me off list at the following e-mail address, and I’ll get those papers off to you right away: [email protected]

Best wishes with all your fishes (and micro cultures, too), Suzanne!

Happy Trails!
Pete Giwojna

Dear Suzanne:

You’re very welcome!

Dig into the material would enjoy your reading. I hope the information proves helpful.

Best of luck with your rearing projects, Sue!

Happy Trails!
Pete Giwojna