Killer Fish

Question
My mother and I have recently set up a freshwater tank (10 gallons). We have about 7 fish in there, 2 of which are smaller than a childs pinkie nail. There is a catfish a silver dollar, and two fish that suck on the walls to clean it. Recently we have noticed the smaller ones dying. Origanilly we had about six of the small fish and all but two have been found either chewed in half, scales (skin) ripped off, or lying at the top with their fins ripped apart. We have no idea which fish may be killing them, and we took one back because it was from Africa, but we don't know what to do. Should we just give them back to the store and try again with just 5 fish that we know aren't aggresive, or should we do an experiment to see which fish is killing the rest. We have noticed one fish attacking the silver dollar (i think that is what it is called) but it has some messed up fins also. What should we do?

Answer
Hi Haley;

The tank is probably still in the break-in period and with so many fish in there the toxins have gotten too much for them. It will cause illness as well as death. Make a water change of 25% every day for the next 3 days. This will lower the toxins so they should all feel better without going into shock.

Here is a link to my article on new tanks to help you through this crazy stage;

http://www.xanga.com/Expert_Fish_Help

Silver Dollars get very large (6" and bigger) so you would be best off taking him back to the fish store. He is also a schooling fish so he would feel better being with some of his own kind. Without knowing what kind of catfish you have I can't say for sure if it is suitable for your little tank. There are several types of algae eating fish too. Let me know what they all look like and hopefully I can tell you what they are.

At Your Service;
Chris Robbins