Just cleaned out my tank and found a dead tetra behind the filter, i hadn't noticed there was one missing (its been a busy week) but doesn't look like its been there long, no sign of anything wrong with it and the others seem fine, have done a huge water change in hope that it hasn't passed anything on to the others, so far all fish seem to be healthy (although the pleco is a little grumpy because he doesn't like water change time). I havn't tested the water as it wont tell me much now i have done the water change so will let the water settle before testing. I now only have 3 tetras, i don't really want to buy more as i'm not that taken with them (would rather wate and see if the others die and replace with something else), will the 3 be ok on their own?