In Vietnamese, the word “chạch” or “cá chạch” refers to either spiny eels (of the family Mastacembelidae) or loaches (of the family Cobitidae). Common loaches or spiny eels in Vietnamese cuisine includes zig-zag eels (Mastacembelus armatus, chạch sông) or tire-track eels (Mastacembelus favus, chạch lấu), pond loaches (Misgurnus anguillicaudatus, chạch bùn or chạch quế or chạch sụn)…
These eel-like fish are often grilled or crispy-fried then get dipped in a sauce made from fish sauce and ripe tamarind paste (Vietnamese: nước mắm me). Dried loaches and spiny eels are also cooked this way.
Pour some vinegar on the loaches and scalp off the slime with a knife blade, then rinse with salty water. Marinate the fish with a little salt, half of chopped chillies and 1/2 tablespoon of rice wine for 10-15 mins.
Coat the fish with a thin layer of crispy flour and fry in hot oil until they turn golden brown. Place the fried fish on kitchen tissues to absorb excess oil.
Place the tamarind paste in a bowl. Pour some hot water over the tamarind. Mash the tamarind well until it feels completely soft. Mix the tamarind water with 1 tablespoon of fish sauce, half of chopped chillies, 1/2 teaspoon of minced garlic.