Carrefour is doing that now these days, but I do not trust them at all, they are perfectly willing to give a food poisoning.
Fish stinks anyway unless you buy it right from fishermen or if you put it in water with lemon like the Japanese do.
Also do not forget that those stores own their own boats but Fresh fish is never really fresh, it's always 15 days old anyway because the ships must sail further and further away to fishing zones .
I am surprised that Carrefour in Warsaw is not great, they would never risk any food poisoning though for they could go out of business.
Alma Supermarket has good fresh fish( smelly too but ok it we don't turn them into sushis) but their selection is really scarce.(Salmon Herring Salmon Herring Carp for Christmas and trout from time to time)