There are several types of fish commonly called "redfish". The edible kinds are the rockfish (genus Sebastes) and the snappers (family Lutjanidae).
The scientific name for the redfish was shown as Sebastes Mustinus, which does not exist, in Star Trek IV. There is a species, on the other hand, with the name Sebastes Mystinus. We can assume that the computer on the HMS Bounty was in error.