I started playing this mod about a week ago and I'm really glad you dudes are maintaining this! The original Mo' Creatures was one of my favorite mods years ago. Anyway, let's get down to business...

This is exactly what the name of this report implies. Fishing nets work on any wild aquatic mob (excluding dolphins and sharks), and they also work on literally any tamed mob. I found this one by accident in Survival using it on my scorpion which was by the ocean and thought it had something to do with water... They don't even need to be in the water. It deletes any equipment a pet may have, though, from saddles to armor/helmets and chests with everything in them. Also, you can use the fishing net to put pets inside blocks. This is easy enough to test with a tamed ostrich - place blocks in a 2x2 square on the ground and release an ostrich using a fishing net. The lower half of the ostrich will be inside those blocks. This isn't the only weird thing happening with ostrich hitboxes, but that's for the next bug report...

Going to be part of the revamped pet amulet which is planned to be entirely rewritten for the future.