The bug
The Respiration enchantment has no effect on water mobs, even though they are capable of suffocating.
To the mods who closed my report on Water Breathing as "works as intended", note that Respiration does not make any implications on what is being breathed.
Although I wouldn't be surprised if you'd close this one as "feature request" or something since squids don't normally spawn with respiration helmets. I'm personally not a fan of the "if it requires an external editor, it's not a bug" attitude, considering Mojang added the custom NBT tags for players to use in their maps. Back when we were using the wiki, Mojang did indeed address bug reports regarding their NBT features - just keep that in mind, please.
How to reproduce
Execute the following commands simultaneously (e.g. via command blocks):
/summon squid ~ ~1 ~ {Air:300s,ArmorItems:[{},{},{},{id:diamond_helmet,Count:1b,tag:{Enchantments:[{id:respiration,lvl:3s}]}}]}/summon squid ~ ~1 ~ {Air:300s}→ ❌ Both squids start suffocating at the same time
Linked issues
Comments 27
Thank you.
I figured the water breathing one would be contested; I decided to post it anyhow since the game mechanics of squid-on-land are still based on them having an air meter. From the programming perspective, Water Breathing is actually just "keep this mob's air meter full", and squid suffocate on land because their air meters are drained slowly outside water. Since Squid are a subclass of EntityWaterMob rather than EntityLiving, they don't inherit many properties that most mobs have, which is why neither Water Breathing nor Respiration work (and in truth, having them work was not needed prior to the latest update).
At any rate, it's good to know a work-around for having land-squid once again may come sometime in the future. The only current workaround I found is having Regeneration counteract the suffocation damage, but that makes them harder to kill... Which, believe it or not, actually manages to be an issue in a map I'm working on 😛
Related to MC-3316
Did the fix of MC-3316 include a fix for this issue aswell?
I'll let the Mojangstas decide on this one, since this actually makes more sense than the waterbreathing one.