This little rodent is one of the best harvesters. They can harvest plenty of wood and thatch, berries, etc.. they also have excellent weight. They have decent melee damage, and here is how to get your own.
1. Make the kibble on whatever device your on.
2. Find this very big beaver. They are found around rivers and build dams.
3. Knock it out with tranq darts
4. Feed the kibble and a bunch of berries (use bio toxin to keep unconscious)
5. If tamed, put the saddle on it and take it home.
6, extra information. Wild castorodies have a chance to have black pearls! But be careful, looking in their dam inventory makes them Argo.
The method I used to tame was picking up the beaver with my crystal wyvern and dropping it in a taming pen. Pretty easy knockouts but their torpor drop rate is INSANITY and you can't leave then for more than 3 minutes. Feed them either mejoberries or crops (kibble is really expensive but if you want to do that, go for it).