Write a brief note on Estuarine Fish

The estuaries and brackish water lakes are grouped into two types.

Open estuaries, including the river mouths, lakes and backwaters, which are always connected with the sea, they may be perennial or seasonal.

Embanked brackish water which are confined areas of estuaries, lakes and backwaters.

The brackish water has certain advantages. It has rich supply of nutrient salts, and there is little variation in pH. Water in brackish water ponds is always alkaline, its pH ranging from 7.5-8.3.

Principal Groups of Brackish Water Fishes:

These are mostly marine species that can tolerate large variations in salinity. Important among these are the clupeids, mullets, catfishes, jaw fishes, threadfins, perches and prawns. Species that are of lesser important are half breaks, garfishes, eels, sharks, rays, flat fishes, oyster etc.

Clupeids:

Important clupeids of the brackish water are Hilsa ilisha, Nematolosa nasus, Pellona sp, SEetipinna sp, Elops sauras, megalops, cyprinoides etc. Of these the Indian shad, Hilsa ilisha is of great importance. The mud shad Nematolosa nasus, provides a regular fishry in the Chilika lake.

Hilsa is the Indian migratory fish and is caught in considerable number in Bengal.

Mullets:

Mullets are the most important of all the culturable brackish water species. Several species are found in the estuarine waters. These are mugli cephalus, M.tade, M.parsia, Rhinomugil corsula etc. Of these Mclasses and mystus sps. In Bengal and Orissa considerable numbers of catfish are caught from November to March.

Perches:

Several species are found in the estuarine waters are of highest importance and fetches good price in the market.

Thread Fins:

The most important species is the Indian salmon, Eleutheronema tetradactylum which is widely distributed all along the coast and is caught along with clupeids and mullets. Other species are polynemus indicus and P.paradiseus, which are found abundantly in the estuaries of Bengal. The fishes ascend the rivers for breeding and are caught in large numbers.

Milk Fish:

Chanos is an important species of the brackish water. Fry are collected in large number along the east coast estuaries during April-June, when they move in large souls in to the shallow tidal creeks.