The first thing is to determine the family. There are three. The traded species of Cynoglossidae and Soleidae come from SE Asia, the species of Achiridae from the Americas.
Cynoglossidae are rare. They are very long and narrow (length is ~five times the width) and taper to a point; the tail fin is imperceptible. They have a rather odd head, elongated and almost triangular. Two species are traded, both strictly freshwater.
The
Soleidae seem to be the most commonly traded ones in the UK. They are rounded and have small tail fins that merge into the fins along the edge of the body with only a slight pinching separating them. There are several species traded and most are difficult to identify. One that is easy to spot is
Brachirus harmandi, becuase it is the only commonly traded sole with dark patches on the
underside of the fish. It is a true freshwater fish. Most of the others want either slightly brackish (e.g.,
Brachirus panoides) or brackish to marine conditions (e.g.,
Brachirus orientalis).
The
Achiridae are superficially similar to the Soleidae but the tail in much larger and more obvious, almost paddle-like. There is a clear separation between it and the fins surrounding the body. There are maybe 3 species traded, of which one,
Catathyridium jenynsii, is a true freshwater fish. The others want brackish to marine conditions.
There's quite a bit more on these fish as well as a listing of the more common species (with links to their FishBase pages) in the
Brackish FAQ.
There is also another useful site just about these fish, but it's in Japanese so you'll have to make do with the pictures and bad translations via Babel Fish.
Cheers,
Neale
Nmonks, is there any way to clearly tell between the species?
/www.fishforums.net/index.php?s=&sho...dpost&p=1212015
. Thanks neale, it's probably a positive ID isnt it? I'll check on the shape later, don't want to stress it too much on it's first day.
