Pixelmon Mod

I discovered something I haven't seen before on pixelmon today. This may be a well known feature but I cannot seem to find any information on it anywhere, so if anyone knows what it is, please enlighten me. I found a wild Numel emitting fire particle effects on its own in the wild. I was unable to get any screenshots of the effect but it stopped after I caught it. Does anyone know what this means?

Sorry if this is a noob question, but I haven't played since long before reforged launched, so I may just be ignorant to this new stuff. Thanks in advance :)

Are you on a server? That's most likely from an active PixelHunt hunt. You can use "/hunt" to see which hunts are active, if I remember that correctly.