Hi KR Nial
I am the the transcriber for the Killaloe register.
https://www.clarelibrary.ie/eolas/coclare/genealogy/don_tran/bmd/baptis…
When preparing the comprehensive list I attempted to give some location where the families may reside.
After reading through Sean Kierse's Land and People of Killaloe Parish, the only place that mention Fish as a residence is on page 62, which indicates Fish Island, Fahy More South.
In respect to your family the Nihil/Nial Mathew with the first two children in the register Margaret (record 4376, year 1844) and Mary (record 4909, year 1846) the family is record as being at 'Killaloe'. Killaloe town Knockyclovaun Towland, has some interest information. Have you viewed the Tithe books for 1824 and 1835?
Landholder: Matthew Nihill (fisherman) Acreage [A.2, R.1, P.0) Tithes $0, s1. d.10, also lists a widow Nihill [mother no name of Mathew?, she could be a Margaret based on the order of children's births?] In appears that Mathew Nihill was working with a John Ryan (fisherman). There is also a Michael Nihill mention as well, see pages 301-302. The Nihil's have a strong connection to the fishing/stone mason industries, also the historic names of the 1800s have carried forward to the 1900, it is possible that the 1901 family that remained in Killaloe were related to your family who migrated, distance cousins/aunts/uncles.
Also see page 307, it lists the following information from the 1901 Census of Knockycolvaun 14. Matthew Niall 36, marble mason, mn; John, b.34, boatmaster, mn; James, b. 32; marble mason, mn; Anne, s, 26. Dressmaker, mn; Elizabeth, 2, 21, assist, dressmaker, mn.
On page 306, it indicates that the type of fish, '...salmon...'
Because I dont have followed absolutely every fact with every family as that would quite a task, I dont believe the original assumption that Fishlane is related to Fish Island, doesnt seem likely since why would the family move from one area to another, the famine could possibly explain this, but I dont have any further evidence to suggest otherwise. Base on the baptism of Sarah (rec 5373, year 1849) where the record does indicate 'Fishlane', this was at the peak of the potato famine, it could have been a temp community in the Killaloe/Knockylovaun Townland. The Killaloe/Knockylovaun Townland was where all the skilled people resided, teachers/schools, churches, publicans/pubs, stone masons, steelsmiths, etc.
On your trip to County Clare, I recommend stopping in the Family Research Centre at Innis also the majority of resources for Killaloe are located at Limerick libaries.
All the best with your research.
Kind Regards
Jeff Fitzsimmons
Adelaide, South Australia