You've taken the all important first step, you've figured out that you made a mistake and you've accepted it. Trust me, this is a common mistake however not everyone can admit they have made a mistake---alot of people say "Well the
LFS employee told me it would be ok and I believe them".
Let me address your overcrowding issue quickly---you have 6 angelfish and 2 convicts. Even when you only had the 2 convicts the tank was really too small for those convicts when full grown. Really I wouldn't suggest anything smaller than a 29 gallon and definitely nothing smaller than a 25 gallon. As for Angelfish, you have 30 inches of angelfish once they mature, that's alot of fish. You could probably keep a pair of Angels in a 20 High but not much more because if they mate up they get aggressive. I'm sure when the
LFS salesperson sold you the fish he did the 1 inch of fish per gallon rule and sold you the fish based on that. That formula doesn't really work well, and I'm sure he didn't take into account their adult size.
OK here are the two problems we need to address
ASAP
1)Separating the Convicts from the Angelfish
2)Finding out what the white slimy thing is and treating it
As I see it you have 3 options for addressing the first problem of separating the angelfish and convicts
1)Go buy yourself a tank divider, this is an inexpensive fix (probably around $10) and can be found at any pet store but it is only a temporary fix since it will only solve the aggression problems but won't address the overcrowding issues
2)Go buy another tank, they can typically be found cheaply in your local classified section
3)Take back the fish to the store, remember this guy is going to be upset but I guarantee you he sold you these fish knowing full well they would be overcrowded and would die. That's how alot of
LFS make money, they continually sell people fish about every month when they die off and the owners want to replace them. If at all possible I would return at least 3 of the healthy angelfish unless you plan on buying about a 55 gallon tank for them.
As for the slimy white stuff problem---
Ideally you would have a
qt tank. But I'm assumingyou don't, therefore you are going to have to treat the entire tank.
1st---Don't just start dumping chemicals in, It will kill your fish much faster than any disease
2nd--Go to the Freshwater-Unhealthy Fish section and start a post with the heading---Unidentified slimy white stuff on angelfish, Please help---or something like that, you will get better help than I can give you
3rd--You need to fix the wounds on your other Angel so Go get some Aquarium Salt and some Melafix from your
LFS (get a tank divider while your there--you can always use one of them), Follow the directions and don't overuse the stuff and the wound should heal rather quickly. And it might help fight off the white stuff which I think is likely a bacterial infection.
That's all I have for now, please keep us updated on what's happening
