I know Mini Crabs are great bottom feeders, but are they aggressive? I added 4 today 2 small 1 large, and 1 medium. The sales consultant said they are not aggressive, but I'm looking for a 2nd opinion. I have a 45 gallon tank fully cycled with 2 Angel fish, 4 Pristella tetras, 4 Red minor Tetras, 3 Red eye tetras, 3 Tiger danios. Take a look at some pics of my tank