lonely

I have 4 fish, 3 cory and a goldfish. My concern here is about the cories, I have had them for a year or more I want to say and at the beginning all three would school together and say a week later its only two that stick together and obvi the other is lonely in a corner or just plain on the...

I have a Lyretail Swordfish in a 10g tank. I have read that it needs a min 30g. Recently all of his tank mates have died for various reasons or been displaced because they were not suitable for each other. It is now the only fish in this tank and doesn't swim around anymore. For the past 2 days...