Currently, I have 10 blood fins in my 75g tetra tank. Yes, they are an awesome looking fish. They will really shine when they get a little more size on them. Try to get a few more of them so that they will shoal up and form a school. Most tetras are shoaling or schooling fish and tend to be very mild mannered when kept in groups of 6 or more. They may become a little nippy or waste away if left singly or in smaller groups.