Gillaroo is the name of a species of trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

 which eats primarily snail

Snail

Snail is a common name applied to most of the members of the molluscan class Gastropoda that have coiled shells in the adult stage. When the word is used in its most general sense, it includes sea snails, land snails and freshwater snails. The word snail without any qualifier is however more often...

s and is only proven to inhabit Lough Melvin

Lough Melvin

Lough Melvin is a lake which is internationally renowned for its unique range of plants and animals. It is located in the northwest of Ireland on the border between County Leitrim and County Fermanagh ....

 in Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

.

Gillaroo is derived from the Irish

Irish language

Irish , also known as Irish Gaelic, is a Goidelic language of the Indo-European language family, originating in Ireland and historically spoken by the Irish people. Irish is now spoken as a first language by a minority of Irish people, as well as being a second language of a larger proportion of...

 for Red Fellow ; this is due to the fish's distinctive colouring. It has a bright, buttery golden colour in its flanks with bright crimson

Crimson

Crimson is a strong, bright, deep red color. It is originally the color of the dye produced from a scale insect, Kermes vermilio, but the name is now also used as a generic term for those slightly bluish-red colors that are between red and rose; besides crimson itself, these colors include...

 and vermilion

Vermilion

Vermilion is an opaque orangish red pigment, similar to scarlet. As a naturally occurring mineral pigment, it is known as cinnabar, and was in use around the world before the Common Era began. Most naturally produced vermilion comes from cinnabar mined in China, and vermilion is nowadays commonly...

 spots. The gillaroo is characterised by these deep red spots and a "gizzard

Gizzard

The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including birds, reptiles, earthworms and some fish. This specialized stomach constructed of thick, muscular walls is used for grinding up food; often rocks are...

", which is used to aid the digestion of hard food items such as water snails.

Experiments carried out by Queens University Belfast established that the Lough Melvin fish are different from brown trout found anywhere else in the world. They feed almost exclusively on bottom living animals (snails, sedge fly larva and freshwater prawns) except during late summer. It is at this time that they come to surface to feed and may be caught on the dry fly. Other lakes reputed to contain the gillaroo are Loughs Neagh

Lough Neagh

Lough Neagh, sometimes Loch Neagh, is a large freshwater lake in Northern Ireland. Its name comes .-Geography:With an area of , it is the largest lake in the British Isles and ranks among the forty largest lakes of Europe. Located twenty miles to the west of Belfast, it is approximately twenty...

, Conn

Lough Conn

Lough Conn is a lake in County Mayo in the province of Connacht in Ireland and covers about 14,000 acres . With its immediate neighbour to the south, Lough Cullin, it is connected to the Atlantic by the River Moy...

, Mask

Lough Mask

Lough Mask is a limestone lough of 22,000 acres in County Mayo, Ireland, north of Lough Corrib. Lough Mask is the upper of the two lakes, which empty into the Corrib River, through Galway, into Galway Bay. The lake is visited for its trout fishing...

 and Corrib

Lough Corrib

Lough Corrib is a lake in the west of Ireland. The River Corrib or Galway river connects the lake to the sea at Galway. It is the second largest lough in Ireland . It covers 178 km² and lies mostly in County Galway with a small area of its northeast corner in County Mayo.The first canal in...

. However the unique gene found in the Lough Melvin trout has not been found in some 200 trout populations in Ireland and Britain. It is therefore now recognised using its own original scientific name, rather than continued inclusion in the widespread , with which it had been synonymised.

Legend has it that St. Brigid was offered chicken to eat on a Friday as she walked through Garrison, County Fermanagh

Garrison, County Fermanagh

Garrison is a small village near Lough Melvin in County Fermanagh, Northern Ireland. The Roogagh River runs through the village. In the 2001 Census it had a population of 357 people...

. Chicken being forbidden on Fridays for members of the Catholic

Catholic

The word catholic comes from the Greek phrase , meaning "on the whole," "according to the whole" or "in general", and is a combination of the Greek words meaning "about" and meaning "whole"...

faith, she was so enraged she threw the entire bird into the river, whereupon it changed into a fish; hence, the "gizzard".