I have had a Black Shark with some cichlids, plecos and other cyprinids, he is about 45 cm long and lives in a 400 L tank, inside my house. Evey time you walk in the room he swims to the front of the tank in curiosity or something, but I have trained him to now eat out of my hand and let me pat him on the head and tummy, he sort of beaches himself on your hand when you stick it at the top of the water and sucks on your finger. One awful time I had a sleep-over, I'm 14, and all my friends were sleeping around the tank in the sleeping bags. And who else but big Blackie decided to jump out pf the tank, and land on my friends head, in some sort of desperation for attention! Everyone woke up and put him back in the tank. My friend with a terrible head ache after a 4 kg fish landed on his head unsuspectingly.