Fish Dying - Help!
I have a 30 g planted, community tank and over the course of the past approximately 2 months, all of my fish have been dying and I can't figure out what is going on. I was hoping someone here could help.
It all started when I bought about 5 cardinal tetras from a local fish store and put them into my tank but did not quarantine them first (lesson learned). The next morning all of the cardinals were gone (never did find them) and at first I suspected that one of the bigger fish was getting them. I went back to the fish store and was asking them about it and they indicated that the fish were probably not healthy to begin with. There were no cardinals left there and they told me that they had had some problem with them and had brought the entire tank to the back for quarantine. Didn't tell me what the problem was (probably didn't know). Since that time, a lot of my fish have been dying off. In the first week or two I think I lost about 6 or 7 fish....2 angels, a guarami, mollys, quite a few tetras. I slowly started to put things together and related it back to these cardinals. Before that, everything was good.
I am still losing fish and one of the latest has been a red-eye tetra that got a big red bulge in its side and died soon thereafter. The LFS said they thought it was a bacterial infection and gave me some tetracycline HCl to mix with the food for medication. Did this for a week (mixed it with brine shrimp), but now I have a red-serpae tetra that is not looking good and I expect to lose him in a few days.
I notice that what seems to happen is that the sick fish will start becoming inactive and just sort of stay in one place unless chased. Looks a bit strange because the fish looks disoriented and will swim a bit sideways or turn vertically. The red-eye was the only one that got the big ugly red bulge in its side, but I am keeping an eye on any others.
I have noticed a few white worms in the substrate (how did they get there?) and don't know if this could be related to the problem. If anyone has any suggestions, please let me know. I only have about 5 fish left, but I don't want to put anymore into the tank until I get this figured out. Thanks in advance.