In Vietnam, cá mát is an umbrella term for several species of carp in the genus Onychostoma. In Vietnamese, the word “mát” means “cool”, however the etymology of the fish name is unknown. Other local Vietnamese names are cá niên, cá sỉnh, or srang. Some common cá mát species include: Onychostoma gerlachi, Onychostoma laticeps, Onychostoma fangi, Onychostoma leptura Onychostoma ovale, Onychostoma dongnaiensis, Onychostoma krongnoensis…
In Vietnam, cá mát fish is distributed mainly in rivers and streams in the middle and upper reaches of large rivers in the northern provinces such as the Red River system (Đà River, Thao River, Lô River, Gấm River), Kỳ Cùng River, Cầu River, Thương River, Mã River. In Central Vietnam, cá mát fish can be found in Lam River, Giăng River (Nghệ An province), in Son River (Quảng Bình province) and the lowest southern distribution limit of cá mát fish is presumed to be in Trà Khúc river, Quảng Nam province. However, recent discoveries of the two new species of Onychostoma (Onychostoma dongnaiensis and Onychostoma krongnoensis) suggest that cá mát can be found as far as Đồng Nai River.
Cá mát is considered as a delicacy fish in central Vietnam, especially in Nghệ An.
Lunar August (the 8th lunar month) is the start of cá mát harvesting season. The fish is found primariily in Giăng River, as well as in some small rivers like Huồi Tắm River. Cá mát fish is considered as both healthy and nutritious, its meat is delicious, fatty, with little bone. The most delicious part of the fish is the head because the head is very soft, and the head bones can be eaten. Cá mát fish is also believed to have beneficial effects on women’s breastfeeding, on reducing cardiovascular problems, and is very suitable for the elderly.
One common dish is braised fish. Firstly, the fish are fried with sauteed Asian shallots. Next, they are slow-braised with pound garlic, chopped chili, and ground black pepper, fish sauce and local Nam Đàn fermented soy bean sauce. Alternately, the fish can be pan-fried and are served with a dipping sauce made of that same fermented soy bean sauce.
If cá mát fish are harvest n large quantities, the locals often grill them. The fish is grilled by using a bamboo clip or a bamboo skewer over hot charcoal. The dipping sauce is ginger fish sauce.
Also, the fish can be used in a local fish soup called cá mát nấu trôi. The cooking method is simple: In a pot of hot water seasoned with hot pungent spices, the fish are added and get cooked.
Cá mát fish are found in the streams of Đakrông and Hướng Hóa districts where the fishing season only lasts from about February to May of the lunar calendar. The cooking method is mainly from the Bru-Vân Kiều and Pako-Vân Kiều ethnic people.
The fish can be grilled and smoked to be used as a preserved food. The dipping sauce for the grill fish is very special. It is made from the fermented cooked fish intestines, which make the condiment slightly bitter. The other ingredient is chilli pepper.
But the most unique condiment is called cheo cá mát. The condiment is made of pound coarse salt, chili pepper, ground cá mát fish meat, and Zanthoxylum pepper (Zanthoxylum rhetsa, similar to Sichuan pepper). Cheo cá mát can be made from either fresh or dried fish. Tradionally, from fresh fish, the first step is to eliminate the muddy smell of the fish, the Vân Kiều people have devised a way to cook. They bring a pot of water with green tea leaves to a boil, and then pour into the pot. After about five minutes, they take them out to scale and remove the intestines. Next step is to remove the rib bones, and the Vân Kiều people use a knife to cut a vertical line from the gills to the bottom of the fish’s tail, removing all two rows of rib bones. And then they removes the tine bones left on the fish fillets. Finally, the fish fillets are ground with other spices. Alternately, the fish meat can be prepared from dried or freshly-grilled fish.
In Quảng Trị, Vân Kiều and Pa Ko people often use cheo cá mát condiment on xôi (sticky rice). The condiment is also commonly paired with roasted pork or boiled chicken.
Quảng Ngãi, Bình Định and other provinces
The Onychostoma fish in called cá niên in these provinces, and found in a few mountainous and midland districts such as Sơn Hà (Quảng Ngãi province), An Lão, Vĩnh Thạnh ( Bình Định province). Cá niên fish can be grilled, cooked with bitter melon, with rau răm (Vietnamese coriander) leaves or deep-fried. Onychostoma fish intestines are even considered as an aphrodisiac.
Grilled Onychostoma fish is a common dish. The condiment for this is made from ground coarse salt, bird’s eye chili and white basil leaves. Sometimes the fish are also steamed and served with the same condiment.
In Quảng Nam province, cá niên is found in the streams of mountainous areas, inhabited by Cơ Tu, Xê Đăng, and Ca Dong ethnic people. Grilled Onychostoma fish is paired with a condiment made from anchovy fish sauce and turmeric, as well as several additional spices. Another notable dish is an Onychostoma fish sour soup with lá giang (Aganonerion polymorphum) leaves, and bamboo sprouts.