That's a pretty clever idea - tried something similiar once with no luck...
I had a chasm and a river on one board, so I created a waterfall into a pond and let the pond drain into the chasm through some grates. I was hoping fish would fall over the waterfall, not be able to go back up it, and be caught in the pond because they couldn't swim through the grates. I did see fish in the pond occasionally, but they didn't seem to stick around for whatever reason. I have started to think that fish just randomly generate on river/pond tiles, swim around and disappear again after a time.
I have built aquariums from glass and filled them up with water. I just can't capture any live fish to put in them
The kennel idea sounds interesting, but it seems farfetched - did that really work? I mean.. warcarp?
Dogs are the only thing I've been able to train into war animals..