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
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.
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!