I have 7 cherry barbs in my 20 gallon (2/3 full) with 2 small crabs. the barbs have no fear, and are really quick and perky. they play a lot and are curious fish, sometimes 3 or 4 will school around my hand in if I am gardening. they love the get tangled in plants and scout caves. they also seem to really like playing in swallow water with strong current... I have a log that resembles a flume, about 2 inches of turbulent water as it meets the surface, and they play in it all day. they also seem to clean out the crab's hide aways, the crabs have given up on catching them.
really awesome fish