Pixies are one seahorse that may actually enjoy a greater life span in captivity than the wild. In nature, winter storms and hurricanes take a heavy toll on their numbers, and very few adult dwarf seahorses survive their first winter; none are known to overwinter twice. A detailed field study marked all the individuals of a Cedar Key population and followed them closely for a period of several years (Strawn 1958). The study revealed that the Cedar Key dwarves grew fast, reached sexual maturity early (within 3 months), and died young, with few surviving for more than a year (Strawn 1953; 1958). No 2 year-old specimens were ever observed. (Strawn 1953; 1958) Thus, their natural life span is believed to be about one year in the ocean. In captivity, experienced hobbyists have kept them for 3+ years and not only can they survive to that ripe old age, they are often still going strong and may even keep breeding well into their third year.
I do small weekly water changes on my dwarf tanks of 10%-15%, rather than the monthly or bimonthly water changes I perform on large setups, but the volume of the water exchanged is so small — just a gallon or so at most — that they are a breeze. Heck, if I mix up a 5-gallon bucket of new artificial salt mix in advance, that provides enough clean, aged saltwater for a month’s worth of water changes on my dwarf tank. When I siphon out the water for the weekly exchange, I use the opportunity to vacuum the substrate and tidy up the tank a bit. Once it settles, I use the water I siphoned out to clean the sponge filters. The whole process, water change and all, takes all of 10 minutes.
But that 10 minutes of weekly maintenance returns wonderful rewards in terms of water quality. With such a small volume of water, the conditions can deteriorate quickly in a dwarf tank, and this modicum of weekly maintenance keeps things running smooth and trouble free.
As Leslie mentioned, your dwarf seahorse tank would not make a good nursery for pelagic H. reidi fry, due to their specialized requirements. However, once your reidi fry make it through their pelagic phase and begin orienting to the substrate and hitching, your Pixie tank would make a fine grow-out tank for your juvenile H. reidi
Commonly known as Pixies or dwarf seahorses, Hippocampus zosterae is the smallest of all the seahorses available to hobbyists. Dwarf seahorses reach a maximum size of about 1.75 inches or 45 mm, half of which is tail. Everyone is amazed at how tiny they are the first time they see dwarf seahorses — picture seahorses that are the size of your thumbnail when fully grown and you’ll have a good idea of what Pixies are like. To me, their diminutive dimensions are a source of endless delight; I find them quaint and charming in the extreme.
I find it endlessly fascinating to witness the seahorse’s entire cycle of life taking place in microcosm on a miniature scale — courting, mating, giving birth, newborns, juveniles and young adults all thriving and growing right alongside the old warhorses.
Best of luck with your seahorses, Nigel!