Convict problem

I thought I saw a thread on here before about someone's convict acting funny ... hardly swimming, staying either up at the top of the water in a corner or on the bottom, mouth kinda stuck open ... am I wrong? I can;t seem to find it anywhere.

I'm asking because I bought a couple convicts a couple weeks ago and 1 of them has been acting this way the past couple days. I'm afraid she's gonna die and I don't know what I can do to help her. I just did routine maintenance on the tank before she started acting funny ... do you think there's any hope or is she doomed?

Now, I did read up on these fish prior to getting them and I decided to try them in my 29/30 community tank. (I know some of you are gonna have a problem with this but it's working for me so I'm not planning on changing) I found some convicts at my local LFS and watched them for about a half hour before deciding for sure on them. I managed to watch them long enough to find a pair. In the course of catching the fish the gal at the store stirred them up pretty well but I did get the pair I had been watching and an extra female. (so I have 1 male and 2 females) They are in the 29/30 gal community tank with 10 small zebra danios, 4 cherry barbs, 4 guppies, 4 mollies, 4 cory cats and a pair of kribs. The tank substrate is 3/4 sand with 1/4 gravel (for plants). I have switched to mostly fake plants but do have live java moss and a couple anacharis plants in there. There are 2 fake stumps (the convict pair have seemed to choose the larger as their home), a piece of drift wood, and a terra cotta cave (which the kribs have taken a liking to. I actually put the convoicts and kribs in there (against some things I've read) because I don't have a tank that I can denote JUST to them YET. Anyway, all these fish are doing remarkable well together (except the 1 female convict described above). As a matter of fact, upon watching the fish interact it seems that by having so many fish in the tank that there isn't just 1 or 2 being picked on. It's like there's just too many for the more aggressive fish to decide on ONE so they just go about their own business. Now they've only been in there together like 2 weeks but ...

Anyway, that's just background on the tank. Does anyone know what's ailing my single female convict? I'm trying to treat with MelFix right now to see if it helps but I don't know what exactly is wrong other then it can't seem to close it's mouth and it just hangs out (at the bottom of the tank lately) by itself. Any suggestions (besides getting rid of any of my fish)as to what is wrong with this fish and what I can do would be appreciated.
 
Do you have enough room in your tank? Convicts can be agressive and sometimes the least agressive fish is forced to the top because there aren't any hiding places for it. Do you have enogh cover?

I could also mean bad circulation in the tank (not enough oxygen) or a water problem. But its porbably because there isnt enough territory for the fish.
 
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