Dear Amanda:
There are currently 16 different species comprising 21 distinct types of captive-bred-and-raised seahorses available in the US, and to my knowledge, none of them are commonly known as "green seahorses." Without a better description or perhaps a photograph to go on, I’m afraid the identity of your mystery seahorses will have to remain an enigma for now.
It’s difficult to say how long you can expect your new seahorses to live without knowing what species they are, but I can tell you that with the exception of dwarf seahorses (Hippocampus zosterae), which typically only survive in the wild for a year or so, all of the seahorses we commonly keep have life spans longer than 2-4 years.
For example, in my experience, cultured seahorses such as Mustangs and Sunbursts (Hippocampus erectus) have a life expectancy of 8-10 years in captivity, it provided with good care, but a life span of 4-6 years is more typical in the home aquarium. (I personally know of one old war horse raised by a colleague of mine that reached the ripe old age of 7 years and 3 months.) At the Ocean Rider facility, I believe some of their original broodstock are older still (10+ years old), but of course the ideal conditions there are far different from the small,-closed-system aquaria and artificial saltwater we hobbyists must rely on.
In short, with proper care your green seahorses should be with you for several years. Best of luck with your new seahorses, Amanda!
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.
