Stevie --
Pipefish are extremely difficult to maintain in captivity without a constant supply of live foods. I have kept seahorses, and they did eventually learn to take frozen mysid shrimps as well as live river shrimp and brine shrimp. But pipefish are so much smaller (narrower) than seahorses that river shrimp aren't an option.
Funnily enough, I bought two pipefish on Saturday, but by Sunday morning they were dead. I'm not sure what I did wrong, but it is possible that because it took me so long to get home on Saturday they were chilled on the trip and weakened. Or if these were brackish water species, then keeping them in soft, acid freshwater may have been a mistake. These are the only reasons I can think of for losing two fish within 12 hours.
Not all pipefish need brackish water, several are truly freshwater animals, such as the Microphis deocata currently on sale at Wildwoods, north London. I don't think these are the species I bought though; I suspect I had some very young Microphis acuelatus, in which case I should have kept them in brackish.
Pipefish need their own tank, or possibly one with a few small gobies, and your main problem is going to be feeding them and identifying them. Since some need brackish water and some fresh, if you aren't sure which you have, you could have problems. Having said that, I would _guess_ the freshwater species would have at least some tolerance of salt, so an SG of 1.003 to 1.005 is perhaps a safe default.
You are right, there is very little reliable about them on the Internet or in books. If you go to the Brackish FAQ (see my signature at the bottom of this) there's a link in the pipefish section to a very useful PDF about keeping them in public aquaria. Many species have been bred in public aquaria, so they aren't fish that are intrisically unable to survive in captivity, it's just they are a pain to identify and to feed, and even experienced aquarists have problems with them.
Cheers,
Neale
