Starbound Mod Mod: Mod Fatties

[Disguy]

I assume you’re referring to the slimes found over here in this topic: Starbound Big Fatties Add-Ons - Expanding Clothes and other small additions - #2 by Tobias1595

They provided the means to spawn them manually just a bit under the download link, here’s the section in particular:

@Tobias1595

The internal names are jellyslimemini , jellyslimenormal and jellyslimebig . To spawn them in, you use /spawnmonster , the same command as for other monsters aswell.
There sadly is no way to spawn multiple at once.

Examples:
/spawnmonster jellyslimenormal for just getting one
/spawnmonster jellyslimenormal 5 for a specific difficulty level (0-10, here 5)
/spawnmonster jellyslimenormal 1 '{"slimeColor":"Green"}' to get a specific color, options are Red , Yellow , Green , Cyan , Blue and Purple