fish compatablity

Question
I started a tank just before christmas.  I let it cycle.  The store told me I bought all community fish however, I have lost a few fish and while I have no proof the kids and I believe that the catfish(I don't remeber the exact name)may be attacking some of the fish at night, or eating them.  
one neon tetra disappearing altogether and one male guppy had its tail eaten and then the next day it was dead.  Needless to say I am heartbroken.

Presently I have two neon tetra, one male guppy, two bleeding heart tetra and the catfish that stays under the tunnel all day long.

Let me know what you think?  Is it possible a tetra or guppy would attack one of its own?  Should I return the catfish, or do I need it to eat algae?

Any advice would be helpful

Thank you
Julie

Answer
Hi Julie,
Thank you for your letter and thanks for sharing your tank mystery with me. No matter what they tell you at the shop when you're making your investment, this is one of the most difficult hobbies in the world. Why? Because it's difficult to watch the cute little fish die under your care. So take heart, this happens to all of us. Even seasoned aquarium keepers may suddenly lose all their fish. For example, through a stupid mistake or accident (the hood and lamp fall in the tank) or through a mystery (why did they suddenly develop ick?). The most common cause of fish loss is over feeding. Another common cause is that the various critters attack each other. This may happen due to crowding, stress, or simply an aggressive creature who bullies smaller, more passive creatures. In this case, I believe the cat fish is the guilty party.
I suggest that you let nature take its course. Then, if you want to stick with the hobby, just keep the survivor(s) and take a few months to get the hang of aquarium care. When you add another fish, make sure it is one that can defend itself. One or two fish is a good place to start. Or you can return the murderous scoundrel. You don't need an algae eater necessarily. Is it a plecostomus? They can get quite large and they do eat fish.
Sometimes an old timer in the tank can get territorial and kill whoever tries to move in. My plecostomus killed a whole generation of fish I tried to introduce after his little friend, the neon tetra died. The plecto was my main pet, whom I loved, so I forgave him. Finally, I got him a 30 gallon tank and put three very big fish in with him. That was fine until he got sick and died. That was sad.
Here is my page for wholistic aquarium care. Feel free to print it out for future reference:
http://steamboats.com/aquarium.html
Please try to see the bigger picture and don't beat yourself up. It's a tricky hobby, but one that you might enjoy once you get the hang of it.
Write back if you want to discuss further.
Nori