What's the largest crustacean one could keep in a tank without it praying upon small fish (~ guppy sized)? And what would it's minimum tank size requirement be?
Shrimp are the only ones I can think of for freshwater. Crawfish and small freshwater crabs would eat any fish they could catch.
Bamboo shrimp get pretty big, and are peaceful. You'd just have to make sure they're getting enough particles in the water column to feed on, because they use their fans to filter feed.
I forgot about the Vampire and Bamboo shrimp (same thing?). They do get huge, relatively speaking. They kind of creep me out, though. My LFS has them quite often. If they’re not feeding in the water column, they’re picking at the sponge filters.
A shame, you'd probably take great pictures of them and their fans! What filtration do you have for photography?
I run a combination of canisters and HOB 0ver 10x the water column. As an example the 37 guppy aquarium has over 700 GPH in filtration. Except for the 150 it only has 1,420 GPH in filtration. The water is so clear the poor things would starve. I service the filters weekly on rotation. HOB one week canisters the next. I have a very old shot of a pair I had many years ago. Not a great shot. I was still using under gravel filters at that time so the water was not crystal.
Over filtration is not a problem, you just need to crush the food finely and get it into the stream of water that the bamboo is looking for. The other option is to turn your filters off while you feed the bamboo.
