This
map from google that was shared earlier shows the marine LFS locations in Singapore. I would suggest calling before going down as some of the places listed have outdated addresses(Shifted/Closed).
This is what I know:
1) J&J Marine Life is no longer at Tanjung Katong Rd.
2) Reborn is no longer at Lavender Street.
3) Aquamarin has consolidated both their outlets and are now at 298 Upper Paya Lebar Rd.
This
map shared by Zadrian reflects the changes above but it includes both marine & FW LFS.