Hello,
Humphead glassfish were discovered in Burma, but the stock that turns up in shops apparently comes from the Thai/Burmese border region. In other words, hundreds of miles inland. There's absolutely no question that these are freshwater.
Every book that says glassfish need to be kept in brackish water is wrong. I suggest you read Schaefer's Aqualog book on brackish water fish, which is the latest and most up-do-date discussion of them. Three species are imported as common glassfish: Parambassis ranga, Parambassis lala, and Parambassis siamensis. Of these Parambassis ranga appears to be the most frequently seen. In the wild, accordingly to the people who collect them, these fish are primarily found in freshwater and only rarely in slightly brackish. They are never found in estuaries and places with very variable salinity (in contrast with monos and scats).
The majority of books copy one another, with the authors having no particular experience of a certain fish (do you really think Axelrod has kept and bred all 6000 species of fish in his atlas?). Schaefer is a collector, and I trust him on this: glassfish of the genus Parambassis come from freshwater.
As you say, Parambassis spp. do fine in very slightly brackish, and this can be compared with figure-8 puffers, also found in freshwater but known to do well (in captivity) in brackish aquaria.
Nonetheless, you can keep them as well, if not better, in freshwater. I have some in a soft, acidic (pH 6.5) aquarium alongside things like cardinals and they are very healthy. They are seemingly immune to white spot, for example, and have much more clearly defined markings. They are also very bold and active, and come to the front of the tank to beg for food, like cichlids, a behaviour I'd not heard about. More often, people describe these fish as "shy and delicate" which they simply are not, when kept well.
Incidentally, a similar situation exists with bumblebee gobies and wrestling halfbeaks; although very occasionally found in brackish water, both more typically occur in fresh water.
Sincerely,
Neale
. They're not brackish water. Need soft to moderately hard, slightly acidic or neutral water, lots of oxygen, low nitrates. Repeat: these are not brackish water fish
Im assuming you mean the humpheads and not the regular glass fish, Ive kept my glassfish in brackish water and theyve been absolutely fine. Every link and book ive ever read said glassfish can tolerate freshwater, but are truely a brackish fish. Also where are the humpheads origins?
