carp-like freshwater fish

[Bruxis]

What is the name of a carp-like freshwater fish with barbels around its mouth ?

[brachiopod]

A few of the cyprinids (carp family) have barbels, including the scaled, leather, and mirror carp (which are all forms of the species Cyprinus carpio); as do the tench (Tinca tinca), and the little gudgeon (Gobio gobio).

However, it's the barbel (Barbus barbus) that you are probably thinking of.

[keithlbw]

i think it is "LOACH" it fits in 26 down anyway

[brachiopod]

Now I find out it's a crossword !

A 'loach' is neither carp-like nor a member of the carp family (cyprinidae).

The roach (Rutilus rutilus) is a cyprinid, appears to fit the crossword, but does not have barbels.

What is the exact clue, the number of letters, and any known letters?

[Xword_addict]

loach loch,
noun a small river-fish of a family (Cobitidae) related to the carp, having a long narrow body and spines round its mouth.

[keithlbw]

LOACH ---- carp-like freshwater fish,family "cobitidae", with a long narrow body and no teeth in the small downward pointing mouth,which is surrounded by barbels. (The Hutchinson  Encyclopedia)