Many estuaries and one brackish water lake is found in the coastline of Odisha. Important amongst them are Mahanadi, Budhabalanga, Baitarani and Chilika Lake.

Brackish water has rich supply of nutrient salts and there is little variation in pH. Estuarine flora consists of several species of algae belonging to myxophyceae and chlorophycae. Diatoms are predominating, which are essential food for the estuarine fishes.

Estuarine Fishes:

These are mainly marine fishes that can tolerate large variations in salinity. Important among these are the clupeids, mullets, catfishes, jawfishes, thread fishes, perches and prawns. Species that are of lesser importance of half-beaks, ger-fishes, eels, sharks, rays, flat fishes, oysters etc.

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Clupeids: Economically important clupeids of the brackish water are Hilsailisa, Nematolosa nasus, Pellona sp, setipinna sp, elops saurus, megalops, cyprinoides etc. Of these Hilsailisha is of great economic importance. Hilsa is a migratory fish and is caught in considerable number from the lower regions of rivers of Odisha and chilika lake. The main catches are after the monsoons from the flooded estuaries of Mahanadi, but some fishery also done during summer and winter months also.

The mud shod, namatolosa nasus, provides a regular fishing in the Chilika lake.

Mullets:

Mullets are the most important of all the culturable brackish water species. Several species are found in the esturine waters. These are mugli cephalus. Mutade, M.persia, Rhinomugil cersula etc. Of these M. cephalus is the largest and Rhinomugli carsula is found in both in fresh and brackish water of Mahanadi and other rivers. The fry of mullets migrate into the brackish water areas and are caught for culture along the tidal creeks and pools.

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The fry of m. Parsia are most common and are available through out the year. The fry of M. cephalus and M. macrolepis are available near the mouth of Chilika Lake. These fry are used for culture in brackish water ponds.

Cat fishes:

Cat fishes are not considered of prime importance, but from a large proportion of the total catch. They are relatively cheap and are consumed of poorer classes. Important estuarine cat fishes are Arius sps, Pangassius Rangassius and mystus sps. In Odisha considerable numbers of cat fishes are caught from November to March.

Arius sps, and osteogeniosus militaries collect together in large numbers for bredding and being sluggish during this perio, are caught in large numbers. This surplus catch is salted or sun-dried according to size and supplied to the interior parts.

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Perches:

Several species are found in the estuarine waters e.g. lates calcarifer, Etroplus suratensis, E.maculatus, Epinephlus sps, Lutjanus sps, Ambassis sps, Therapan sps. Of these betki (Lates calcarifer) is of highest importance and fetches good price in the market. Fry of betki enter into the rivers along with tide.

Thread fins:

The most importance species in the Indian Salmon. Eleutheronema tetradoctylum which is widely distributed all along the coast and is caught along with clupeids and mullets. Other species and polynemus indicus and P. Paradiseus which are found abundantly in the estuaries of Odisha. The fishes ascend the rivers for breeding and are caught in large numbers.

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Milk fish:

Chanos chanous is an important species of the brackish water. Fry are collected in large numbers along the coast estuaries during April-June, when they move in large shoals into shallow tidal creeks.

Prospects of estuarine fish culture of our state: Though extensive coastline exists for brackish water fish culture, very little of it is utilized for the culture of fish.

River beds and creeks in the estuarine areas get silted up due to the action of tide and in due course such areas are reclaimed for agriculture purposes by constructing embankments to keep away flood and tidal water. Some portions of such reclaimed areas are too low for cultivation and are generally used for fish farming.

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Many of the reclaimed areas are provided with additional outer bundh. Water is let in during high tide through sluice gates and brings in several species of fishes and fish seeds. If the predatory and weed fishes are not allowed to enter into the bundhas, proper fertilization is done, the yield can be increased considerably.