The Welsh range, which comprises oysters, mussels, sea bass and trout, went into stores across Wales this week.
It was part of Morrisons' policy to support and encourage locally sourced produce, said buying manager Janine Watson. "We take pride in our fresh fish counters stocking more than 50 species, which are 100%-sustainable, and we hope Welsh shoppers enjoy our new range," she said.
The Welsh Assembly Government's Building Sustainable Business in the Welsh Fishing Industry programme assisted in developing the range.
Previous supply chain difficulties had meant that most Welsh fish had not been available to Welsh consumers, said rural affairs minister Elin Jones.
"We are keen to further improve the availability of Welsh fish within Welsh supermarkets," she said.