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 biochambers, which turns many people off of using them. Most of these shipments end up going to waste as well because of the low energy costs of biochambers and the large rocket capacity of bioflux/eggs/fish. Fish breeding in theory allows you to spend about 1/3 of your nutrient supply to reset this timer, making shipments much less wasteful and urgent with proper design.Side effects should be fairly limited. Fish breeding for quality is still best done on Nauvis for biter egg nutrients, although would be possible on Gleba. Combat relevance is pretty low especially as bioflux is definitely available.
