Another idea for a quality seed downside is more spores. If legendary seeds/trees produced 6x spores, I still think it would be probably be too strong but it would definitely be a more interesting choice.

TL;DR
Remove the surface restrictions on the fish breeding recipe.

Why?
Fish breeding on other surfaces without native nutrients can encourage building nutrient banks and use of biochambers. Currently Fulgora, Vulcanus and platforms need nutrient shipments at least every 2 hours to rely upon ...