According to the local authority website of Leiden in The Netherlands:
There are many fish in Leiden.
In Cronesteyn, Park Merenwijk, Park Roomburg and Stevenspark, and elsewhere, there are quite some fish, including roach relatives (including the protected European bitterling [see also here and here]) and perch.
The protected spined loach … is in many ditches in Leiden; also the northern pike (who, differently from the spined loach, likes clear water, else he cannot see his prey) is not uncommon in Leiden.
In Cronesteyn, also the belica was caught once.
Fish in the St. Lawrence river, Canada: here.