Factorio Forums

Actual behavior:
The +50% productivity boost is applied to the 3 fish of output, instead of only applying to the excess over the catalyst.

Instead reducing the nutrient cost per fish down to 2/3rd to 66.6% it's instead reduced by (2/3)^2 for a nutrient cost of only 44.4 per fish.

Expected behavior:
Catalysts in "Fish breeding" follow regular rules for catalysts - namely not being subject to productivity boosts!

PS:
It looks as if this had already been exploited during beta, so the weird choice was made to exclude both the "Fish breeding" and "Nutrients from fish" recipes from both quality and productivity modules, quoting a weird "infinite loop". (There is actually one if both recipes would be allowed producitiy modules, and there is a trivial one if the first one is allowed productivity modules while this bug isn't fixed!)

(And going by older dev statements, "Fish breeding" would also apply quality upgrades to the catalyst by accident?!)

Once this bug is fixed, it should be safe though to enable quality and/or productivity for the "Fish breeding" recipe at last.

This bug is not present on the "Pentapod egg" recipe.

Quality modules is unfortunately an ALL or NOTHING deal. That is ALL of the outputs get upgraded to the next quality tier, or NONE of them do. There currently is not a recipe prototype to "ignored_by_quality" on some count of the output, like there is for "ignored_by_productivity"

Also see 122068 Fish Breeding and Nutrients from Fish Lack Correct Module Support.

I sentence you... to gleba!

Fixed for 2.0.25.

This recipe is already pretty obsolete and meme-tier and getting nerfed even more.
I've planned for a long time for quality gleba science from quality fish breeding from quality biter eggs: (this is making 2k instead of 3k uncommon/min rn due to bioflux shortage)
This setup is already borderline unscalable and inefficient compared directly to biter eggs to nutrients; before this fix, fish to nutrients vs. biter eggs to fish to nutrients was 37.5:50; now I imagine the ratio would be way worse. This recipe has basically 0 use outside this extremely niche use case, and the other forum post mentions other points. I'm not advocating for an infinite fish nutrient loop, but seeing this fix ruin my plan for quality gleba science is rather disappointing. Now I have to either give up on this awesome plan or transport a promethium-level amount of eggs to Gleba, please consider a rebalance to this recipe.