An estuary is where the mouth of a river meets the sea. In Galway Bay, there is a far reaching, life-rich estuary where the River Corrib reaches its conclusion. It is home to dozens of species of animals: crustaceans such as Shore Crab, Prawn, and Shrimp; small fish including Common Goby, Dragonet and Lesser Weever; and juvenile fish such as young Cod, Whiting and Plaice.

During the Spring and Autumn, when rain-fall is at its highest, there can be 260,000 litres of fresh water pouring into Galway Bay from the Corrib every second. On small and low tides this can be the dominant factor, and the shoreline reaches of Galway Bay can have a layer of fresh river water several feet deep blocking out the salt ocean water of the Atlantic.

Fish which thrive in the fluctuating salinities of the estuary include Flounder, Common Eel and Grey Mullet.

Our Estuary exhibit offers a glimpse of the animals which make the mouth of the River Corrib their home. Lying camouflaged amongst the sand we have Plaice, Flounder and Dover Sole, and slowly crawling among the rocks and weed are Crabs and Whelks. But it is our Grey Mullet, of which there are literally thousands in the Corrib estuary, which immediately catch the eye. They are shy, but inquisitive fish, and as a group of visitors forms round the tank, they will come to the front in hope of a morsel of bread to nibble on. Indeed, they are so used to people by now that they will come right to the surface and take bread, one of their favourite foods, straight from your hand!