I think an item/structure to duplicate fish would be cool. The value or difficulty of the fish could determine how long it takes to complete a cycle and all fish obtained from the object would be of base quality. Legendary fish should obviously be excluded. This way you could duplicate out of season fish I know you love calamari Pierre but it’s Spring and squid are only available in Winter. It could be a craftable like the crystalarium (make it available only after obtaining a high fishing skill or after catching every fish) or a physical structure Robin can build for you. What do you all think?
It would be nice to have a fish tank or pond... something to keep the legendary fish you caught in instead of a chest.
You don’t have to stick them in a chest. You can plop them down on any table to display them. There are a couple tables that look damn decent as display tables.
legendary fish on a table seems so weird, but i'd love your suggestion legendary fish in a tank would be nice, too, except you cannot duplicate them
There are a few mods that may be what you're looking for: Fish Breeding Tanks: https://www.nexusmods.com/stardewvalley/mods/3498 Fish Tank: https://www.nexusmods.com/stardewvalley/mods/205 Though I don't think this one actually lets you put fish in the tank, it's more just a decoration. Fish Plaques: https://www.nexusmods.com/stardewvalley/mods/1394 Currently only for the Legendary Fish.