I had three goldfish in my five gallon tank and my friend purchased an algae eater (black fish with long tail that sucks on the sides, don't know the specific name). He was putting algae pellets in the bottom to feed the algae fish and I noticed the water was getting a little dirty but nothing too bad. Yesterday, after seeing them swim around 10 minutes earlier, I noticed all three goldfish were dead, 2 at the bottom and 1 floating at the top. It was a really horrifying/sad sight. Now, we have the option to start over and I am thinking going with another kind of fish. I have the 5 gallon hex tank and want to fill it with a few freshwater fish but I want to avoid goldfish because of the mess they make. Does anyone have any suggestions of some cool looking fish I can fill it with? Thanks.