What is the lifespan of Cardinal tetras? Do these tetras have a particular weakness? I gave some Cardinal tetras to a friend and they died one after the other. The tank has a pair of Med sized Angels, Rams, SAEs,Clown loach and Otos. Some Cardinals were bought 3 weeks ago and they also died one by one. Of the 20 Cardinals,only 7-8 are left. What's causing the death of these fish?