Dear Lisa:
Thanks for the update! It’s good to hear that so many of your newborns are still going strong, eating well, growing fast, and just thriving in general. Well done — keep up the good work!
To answer your question, there are two high risk periods when rearing during which there tends to be a spike in the mortality rates. The first of these high mortality peaks occurs when seahorse fry that undergo a pelagic phrase are going through their free-swimming stage of development. As you know, during their pelagic period, the newborns drift freely with the plankton and are attracted to sunlight (phototactic), which draws them up to the surface during the day in order to feed on the abundant zooplankton. This is a risky stage of life because the surface huggers tend to gulp air while feeding at the surface and often suffer fatal buoyancy problems as a result, and may even become entrapped by surface tension. For these reasons, most hobbyists find that mortality is very high during the pelagic phase.
For Mustangs and Sunbursts (Hippocampus erectus) fry, the pelagic phase may last for two weeks or more. Your fry are in the midst of this stage of development right now, Lisa, and if you hadn’t weeded out those 25 newborns that had ingested air, chances are they would be drying in droves right now. You saved yourself from some potential problems by culling them out early on in the rearing process.
In general, the older the fry are and the more that they grow, the more survivorship improves and the fewer mortalities there will be among the juveniles. But there is a second peak in the mortality rates at the time when the juveniles are making the difficult transition from live prey to frozen foods. Some of them just seem to have a difficult time making the adjustment to nonliving food and are lost as a result.
This second spike in the mortality rates usually occurs around 3-6 weeks of age when the youngsters are ready to be weaned onto frozen foods. So that’s another hurdle you have yet to cross before you can start to feel like the youngsters are out of the woods and facing better odds of surviving to maturity.
Probably the greatest risk facing your fry in the months ahead is that the demands of your daily life are simply going to intrude more and more, and eventually force you to begin to neglect them as a result. Or the Herculean task that lies ahead may simply wear you down until you begin to skimp on the water changes, feedings, and maintenance of your nursery and rearing tanks, to the detriment of the juveniles. Many times that’s all but inevitable for the home breeder. And there is always the chance that an outbreak of disease or parasites can wipe out a crowded nursery tank at any time. Things can go south in our hurry when you’re dealing with such a small volume of water with such limited filtration options…
For these reasons, it is very rare for home hobbyists to have much success during their first attempts at rearing. There is a always a steep learning curve when it comes to rearing the newborns, and it’s quite common — perhaps even the rule — for the home breeder to lose the entire brood during his first few tries. But as you refine your methods and become more proficient at providing suitable live foods for the newborns and work out the feeding regimen that’s most efficient for your particular circumstances, your results will get better. You will have more of the fry surviving for longer periods, until eventually you are able to raise a few of the fry from a few of the broods to maturity. I know many Ocean Rider owners that are successfully raising at least some of their offspring.
And in your case, Lisa, I think you may have a better chance of beating the odds with your first brood because of the prolonged pregnancy they underwent. As we discussed briefly before, and extended pregnancy increases the size and vigor of the newborns and improves their survivorship as a result.
Best of luck with your Sunburst babies, Lisa! Here’s hoping your diligence is rewarded and you are able to raise some of them all the way to maturity.
Happy Trails!
Pete Giwojna
Ocean Rider, Inc. is an Organic Hawaiian-Based Seahorse Aqua-Farm & Aquarium that Follows Strict Good Farming Practices in Raising Seahorses and Other Aquatic Life.
